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Bibliography on: Telomeres

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ESP: PubMed Auto Bibliography 27 May 2022 at 01:53 Created: 


Wikipedia: A telomere is a region of repetitive nucleotide sequences at each end of a chromosome, which protects the end of the chromosome from deterioration or from fusion with neighboring chromosomes. Its name is derived from the Greek nouns telos (τέλος) "end" and merοs (μέρος, root: μερ-) "part". For vertebrates, the sequence of nucleotides in telomeres is TTAGGG, with the complementary DNA strand being AATCCC, with a single-stranded TTAGGG overhang. This sequence of TTAGGG is repeated approximately 2,500 times in humans. In humans, average telomere length declines from about 11 kilobases at birth to less than 4 kilobases in old age,[3] with average rate of decline being greater in men than in women. During chromosome replication, the enzymes that duplicate DNA cannot continue their duplication all the way to the end of a chromosome, so in each duplication the end of the chromosome is shortened (this is because the synthesis of Okazaki fragments requires RNA primers attaching ahead on the lagging strand). The telomeres are disposable buffers at the ends of chromosomes which are truncated during cell division; their presence protects the genes before them on the chromosome from being truncated instead. The telomeres themselves are protected by a complex of shelterin proteins, as well as by the RNA that telomeric DNA encodes.

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Citations The Papers (from PubMed®)


RevDate: 2022-05-25

Courtney MG, Roberts J, K Godde (2022)

How social/environmental determinants and inflammation affect salivary telomere length among middle-older adults in the health and retirement study.

Scientific reports, 12(1):8882.

Social epidemiology posits that chronic stress from social determinants will lead to a prolonged inflammatory response that may induce accelerated aging as measured, for example, through telomere length (TL). In this paper, we hypothesize variables across demographic, health-related, and contextual/environmental domains influence the body's stress response, increase inflammation (as measured through high-sensitivity C-reactive protein (hs-CRP)), and thereby lead to shortening of telomeres. This population-based research uses data from the 2008 Health and Retirement Study on participants ages ≤ 54-95 + years, estimating logistic regression and Cox proportional hazards models of variables (with and without confounders) across the domains on shortened TL. A mediation analysis is also conducted. Contrary to expectations, hs-CRP is not associated with risk of shortened TL. Rather, factors related to accessing health care, underlying conditions of frailty, and social inequality appear to predict risk of shorter TL, and models demonstrate considerable confounding. Further, hs-CRP is not a mediator for TL. Therefore, the social determinants of health examined do not appear to follow an inflammatory pathway for shortened TL. The finding of a relationship to social determinants affecting access to health care and medical conditions underscores the need to address social determinants alongside primary care when examining health inequities.

RevDate: 2022-05-25

Koller A, Brandl C, Lamina C, et al (2022)

Relative Telomere Length Is Associated With Age-Related Macular Degeneration in Women.

Investigative ophthalmology & visual science, 63(5):30.

Purpose: Relative telomere length (RTL) is a biomarker for physiological aging. Premature shortening of telomeres is associated with oxidative stress, which is one possible pathway that might contribute to age-related macular degeneration (AMD). We therefore aimed to investigate the association between RTL and AMD in a well-characterized group of elderly individuals.

Methods: We measured RTL in participants of the AugUR study using a multiplex quantitative PCR-based assay determining the ratio between the telomere product and a single-copy gene product (T/S ratio). AMD was assessed by manual grading of color fundus images using the Three Continent AMD Consortium Severity Scale.

Results: Among the 2262 individuals 70 to 95 years old (627 with AMD and 1635 without AMD), RTL was significantly shorter in individuals with AMD compared to AMD-free participants. In age- and sex-adjusted logistic regression analyses, we observed an 8% higher odds for AMD per 0.1 unit shorter RTL (odds ratio [OR] = 1.08; 95% confidence interval [CI], 1.02-1.14; P = 0.005). The estimates remained stable when adjusted for smoking, high-density lipoprotein cholesterol, cardiovascular disease, diabetes, and hypertension. Interestingly, this association was only present in women (OR = 1.14; 95% CI, 1.06-1.23; P < 0.001), but not in men (OR = 1.01; 95% CI, 0.93-1.10; P = 0.76). A significant sex-by-RTL interaction on AMD was detected (P = 0.043).

Conclusions: Our results show an association of RTL with AMD that was restricted to women. This is in line with altered reactive oxygen species levels and higher telomerase activity in women and provides an indication for a sex-differential pathway for oxidative stress and AMD.

RevDate: 2022-05-24

Armanios M (2022)

The Role of Telomeres in Human Disease.

Annual review of genomics and human genetics [Epub ahead of print].

Telomere biology was first studied in maize, ciliates, yeast, and mice, and in recent decades, it has informed understanding of common disease mechanisms with broad implications for patient care. Short telomere syndromes are the most prevalent premature aging disorders, with prominent phenotypes affecting the lung and hematopoietic system. Less understood are a newly recognized group of cancer-prone syndromes that are associated with mutations that lengthen telomeres. A large body of new data from Mendelian genetics and epidemiology now provides an opportunity to reconsider paradigms related to the role of telomeres in human aging and cancer, and in some cases, the findings diverge from what was interpreted from model systems. For example, short telomeres have been considered potent drivers of genome instability, but age-associated solid tumors are rare in individuals with short telomere syndromes, and T cell immunodeficiency explains their spectrum. More commonly, short telomeres promote clonal hematopoiesis, including somatic reversion, providing a new leukemogenesis paradigm that is independent of genome instability. Long telomeres, on the other hand, which extend the cellular life span in vitro, are now appreciated to be the most common shared germline risk factor for cancer in population studies. Through this contemporary lens, I revisit here the role of telomeres in human aging, focusing on how short and long telomeres drive cancer evolution but through distinct mechanisms. Expected final online publication date for the Annual Review of Genomics and Human Genetics, Volume 23 is October 2022. Please see for revised estimates.

RevDate: 2022-05-24

Farladansky-Gershnabel S, Dekel N, Biron-Shental T, et al (2022)

Spontaneous Preterm Birth: Elevated Galectin-3 and Telomere Shortening May Reflect a Common Pathway of Enhanced Inflammation and Senescence.

Reproductive sciences (Thousand Oaks, Calif.) [Epub ahead of print].

Preterm delivery complicates 5-12% of pregnancies and is the primary cause of neonatal morbidity and mortality. The pathophysiology of preterm labor and parturition is not fully known, although it is probably related to inflammation and placental senescence. Telomere shortening is related to senescence and galectin-3 (Gal-3) protein is involved in cell growth, differentiation, inflammation, and fibrosis. This study examined changes in Gal-3 expression and telomere homeostasis (which represent inflammatory and stress markers) in maternal blood and placental tissue of spontaneous preterm births (SPTB) and uncomplicated, spontaneous term pregnancies (NTP) during labor. Participants included 19 women with NTP and 11 with SPTB who were enrolled during admission for delivery. Maternal blood samples were obtained along with placental tissue for Gal-3 analysis and telomere length evaluation. Gal-3 protein expression in placental tissue was increased in SPTB compared to NTP (fold change: 1.89 ± 0.36, P < 0.05). Gal-3 immunohistochemistry demonstrated strong staining in placental extravillous trophoblast tissue from SPTB. Maternal blood levels of Gal-3 protein were elevated in SPTB compared to NTP (19.3 ± 1.3 ng/ml vs. 13.6 ± 1.07 ng/ml, P = 0.001). Placental samples from SPTB had a higher percentage of trophoblasts with short telomeres (47.6%) compared to NTP (15.6%, P < 0.0001). Aggregate formation was enhanced in SPTB (7.8%) compared to NTP (1.98%, P < 0.0001). Maternal blood and placental samples from SPTB had shorter telomeres and increased Gal-3 expression compared to NTP. These findings suggest that increased senescence and inflammation might be factors in the abnormal physiology of spontaneous preterm labor.

RevDate: 2022-05-23

Roast MJ, Eastwood JR, Aranzamendi NH, et al (2022)

Telomere length declines with age, but relates to immune function independent of age in a wild passerine.

Royal Society open science, 9(4):212012 pii:rsos212012.

Telomere length (TL) shortens with age but telomere dynamics can relate to fitness components independent of age. Immune function often relates to such fitness components and can also interact with telomeres. Studying the link between TL and immune function may therefore help us understand telomere-fitness associations. We assessed the relationships between erythrocyte TL and four immune indices (haptoglobin, natural antibodies (NAbs), complement activity (CA) and heterophil-lymphocyte (HL) ratio; n = 477-589), from known-aged individuals of a wild passerine (Malurus coronatus). As expected, we find that TL significantly declined with age. To verify whether associations between TL and immune function were independent of parallel age-related changes (e.g. immunosenescence), we statistically controlled for sampling age and used within-subject centring of TL to separate relationships within or between individuals. We found that TL positively predicted CA at the between-individual level (individuals with longer average TL had higher CA), but no other immune indices. By contrast, age predicted the levels of NAbs and HL ratio, allowing inference that respective associations between TL and age with immune indices are independent. Any links existing between TL and fitness are therefore unlikely to be strongly mediated by innate immune function, while TL and immune indices appear independent expressions of individual heterogeneity.

RevDate: 2022-05-21

Zhang JC, Li SJ, Guo JY, et al (2022)

Urinary cadmium and peripheral blood telomere length predict the risk of renal function impairment: a study of 547 community residents of Shanxi, China.

Environmental science and pollution research international [Epub ahead of print].

Few reports have investigated the predictive value of urinary cadmium (UCd) and telomere length on renal function impairment. Therefore, we constructed nomogram models, using a cross-sectional survey to analyze the potential function of UCd and telomere length in renal function impairment risk. We randomly selected two community populations in Shanxi, China, and general information of the subjects was collected through face-to-face questionnaire surveys. Venous blood of subjects was collected to detect absolute telomere length (ATL) by real-time quantitative chain reaction (RT-PCR). Collecting urinary samples detected UCd and urinary N-acetyl-β-d-glucosaminidase (UNAG). Estimated glomerular filtration rate (eGFR) was obtained based on serum creatinine (SCr). Nomogram models on risk prediction analysis of renal function impairment was constructed. After adjusting for other confounding factors, UCd (β = 0.853, 95% confidence interval (CI): 0.739 ~ 0.986) and ATL (β = 1.803, 95%CI: 1.017 ~ 1.154) were independent risk influencing factors for increased UNAG levels, and the risk factors for eGFR reduction were UCd (β = 1.011, 95%CI: 1.187 ~ 1.471), age (β = 1.630, 95%CI: 1.303 ~ 2.038), and sex (β = 0.181, 95%CI: 0.105 ~ 0.310). Using UCd, ATL, sex, and age to construct the nomogram, and the C-statistics 0.584 (95%CI: 0.536 ~ 0.632) and 0.816 (95%CI: 0.781 ~ 0.851) were obtained by internal verification of the calibration curve, C-statistics revealed nomogram model validation was good and using decision curve analysis (DCA) confirmed a good predictive value of the nomogram models. In a nomogram model, ATL, UCd, sex, and age were detected as independent risk factors for renal function impairment, with UCd being the strongest predictor.

RevDate: 2022-05-19

Dempsey PC, Musicha C, Rowlands AV, et al (2022)

Author Correction: Investigation of a UK biobank cohort reveals causal associations of self-reported walking pace with telomere length.

Communications biology, 5(1):498 pii:10.1038/s42003-022-03459-w.

RevDate: 2022-05-19

Bhargava R, Lynskey ML, RJ O'Sullivan (2022)

New twists to the ALTernative endings at telomeres.

DNA repair, 115:103342 pii:S1568-7864(22)00075-1 [Epub ahead of print].

Activation of a telomere maintenance mechanism is key to achieving replicative immortality. Alternative Lengthening of Telomeres (ALT) is a telomerase-independent pathway that hijacks the homologous recombination pathways to elongate telomeres. Commitment to ALT is often associated with several hallmarks including long telomeres of heterogenous lengths, mutations in histone H3.3 or the ATRX/DAXX histone chaperone complex, and incorporation of non-canonical telomere sequences. The consequences of these genetic and epigenetic changes include enhanced replication stress and the presence of transcriptionally permissive chromatin, which can result in replication-associated DNA damage. Here, we detail the molecular mechanisms that are critical to repairing DNA damage at ALT telomeres, including the BLM Helicase, which acts at several steps in the ALT process. Furthermore, we discuss the emerging findings related to the telomere-associated RNA, TERRA, and its roles in maintaining telomeric integrity. Finally, we review new evidence for therapeutic interventions for ALT-positive cancers which are rooted in understanding the molecular underpinnings of this process.

RevDate: 2022-05-19

Wong KK, Cheng F, Mao D, et al (2022)

Vitamin D levels during pregnancy are associated with offspring telomere length: a longitudinal mother-child study.

The Journal of clinical endocrinology and metabolism pii:6588722 [Epub ahead of print].

CONTEXT: Leukocyte telomere length (LTL) is a biomarker of biological aging and is associated with metabolic diseases such as type 2 diabetes. Insufficient maternal vitamin D was associated with increased risk for many diseases and adverse later life outcomes.

OBJECTIVE: This study investigates the relationship between vitamin D levels and offspring LTL at early life.

DESIGN: Observational longitudinal cohort study.

SETTING: Hospital-based cohort study.

POPULATION: Eligible mother-child pairs from the HAPO Hong Kong Field Centre, with 853 offspring at age 6.96 ± 0.44 (mean ± SD) years.

MAIN OUTCOMES MEASURES: LTL was measured using real-time polymerase chain reaction while serum vitamin D metabolites 25(OH)D2, 25(OH)D3 and 3-epi-25(OH)D3 were measured in maternal blood (at gestation 24-32 weeks) and cord blood by liquid chromatography-mass spectrometry.

RESULTS: LTL at follow-up was significantly shorter in boys compared to girls (p<0.001) at age 7. Childhood LTL was negatively associated with childhood BMI (β ± SE=-0.016 ± 0.007)(p=0.02) and HOMA-IR (β ± SE=-0.065 ± 0.021)(p=0.002). Multiple linear regression was used to evaluate the relationship between 25(OH)D and LTL, with covariate adjustments. Childhood LTL was positively correlated with total maternal 25(OH)D (0.048 ± 0.017)(p=0.004) and maternal 3-epi-25(OH)D3 (0.05 ± 0.017)(p=0.003), even after adjustment for covariates. A similar association was also noted for cord 3-epi-25(OH)D3 (0.037 ± 0.018)(p=0.035) after adjustment for offspring sex and age.

CONCLUSIONS: Our findings suggest 25(OH)D3 and 3-epi-25(OH)D3 in utero may impact on childhood LTLs, highlighting a potential link between maternal vitamin D and biological aging.

RevDate: 2022-05-19

Zahid S, Aloe S, Sutherland JH, et al (2022)

Ustilago maydis telomere protein Pot1 harbors an extra N-terminal OB fold and regulates homology-directed DNA repair factors in a dichotomous and context-dependent manner.

PLoS genetics, 18(5):e1010182 pii:PGENETICS-D-21-01605.

The telomere G-strand binding protein Pot1 plays multifaceted roles in telomere maintenance and protection. We examined the structure and activities of Pot1 in Ustilago maydis, a fungal model that recapitulates key features of mammalian telomere regulation. Compared to the well-characterized primate and fission yeast Pot1 orthologs, UmPot1 harbors an extra N-terminal OB-fold domain (OB-N), which was recently shown to be present in most metazoans. UmPot1 binds directly to Rad51 and regulates the latter's strand exchange activity. Deleting the OB-N domain, which is implicated in Rad51-binding, caused telomere shortening, suggesting that Pot1-Rad51 interaction facilitates telomere maintenance. Depleting Pot1 through transcriptional repression triggered growth arrest as well as rampant recombination, leading to multiple telomere aberrations. In addition, telomere repeat RNAs transcribed from both the G- and C-strand were dramatically up-regulated, and this was accompanied by elevated levels of telomere RNA-DNA hybrids. Telomere abnormalities of pot1-deficient cells were suppressed, and cell viability was restored by the deletion of genes encoding Rad51 or Brh2 (the BRCA2 ortholog), indicating that homology-directed repair (HDR) proteins are key mediators of telomere aberrations and cellular toxicity. Together, these observations underscore the complex physical and functional interactions between Pot1 and DNA repair factors, leading to context-dependent and dichotomous effects of HDR proteins on telomere maintenance and protection.

RevDate: 2022-05-19

Gong H, Yu Q, Yuan M, et al (2022)

The Relationship between Dietary Copper intake and Telomere Length in Hypertension.

The journal of nutrition, health & aging, 26(5):510-514.

BACKGROUND: More indications proved that diet might be involved in the telomere length, a marker of biological aging and chronic diseases. Copper is widely viewed as one of the essential elements in the diet. Therefore, this study aimed to evaluate the relationship between telomere length and dietary copper intake in hypertension and provide a basis for guiding dietary copper intake in patients with hypertension.

METHODS: The data was collected from the National Health and Nutrition Examination Survey (NHANES) in 1999-2000 and 2001-2002. The relevance between telomere length and dietary copper intake in hypertension is assessed using a multivariable linear regression model.

RESULTS: We gathered 1,867 participants with hypertension with assessed telomere length and dietary copper intake. We found that one unit increasing log-transformed dietary copper intake in hypertension was significantly associated with longer telomere length base pair (bp) (β = 112.20, 95% confidence interval [CI]: 5.48, 218.92), after controlling for covariates, including age, sex, ethnicity, body mass index (BMI), physical activity, and taking medication for hypertension. For the age group, we found that one unit increasing log-transformed dietary copper in hypertension was associated with longer telomere length (β = 237.95, 95% CI: 114.39, 361.51) in the age group >45 years. The grouping was based on whether the participants take medication for hypertension. We found that one unit increasing log-transformed dietary copper in hypertension was associated with longer telomere length (β = 116.47, 95% CI: 0.72, 232.21) in the group that takes medication for hypertension.

CONCLUSIONS: This study demonstrates that dietary copper intake was associated with longer telomere length in patients with hypertension, which provides evidence for guiding dietary copper intake in patients with hypertension. However, further studies are needed to evaluate the effect of copper supplementation on telomere length in patients with hypertension in well-designed random control studies and prospective studies.

RevDate: 2022-05-18

Pearce EE, Alsaggaf R, Katta S, et al (2022)

Telomere length and epigenetic clocks as markers of cellular aging: a comparative study.

GeroScience [Epub ahead of print].

Telomere length (TL) and DNA methylation-based epigenetic clocks are markers of biological age, but the relationship between the two is not fully understood. Here, we used multivariable regression models to evaluate the relationships between leukocyte TL (LTL; measured by qPCR [n = 635] or flow FISH [n = 144]) and five epigenetic clocks (Hannum, DNAmAge pan-tissue, PhenoAge, SkinBlood, or GrimAge clocks), or their epigenetic age acceleration measures in healthy adults (age 19-61 years). LTL showed statistically significant negative correlations with all clocks (qPCR: r = - 0.26 to - 0.32; flow FISH: r = - 0.34 to - 0.49; p < 0.001 for all). Yet, models adjusted for age, sex, and race revealed significant associations between three of five clocks (PhenoAge, GrimAge, and Hannum clocks) and LTL by flow FISH (p < 0.01 for all) or qPCR (p < 0.001 for all). Significant associations between age acceleration measures for the same three clocks and qPCR or flow FISH TL were also found (p < 0.01 for all). Additionally, LTL (by qPCR or flow FISH) showed significant associations with extrinsic epigenetic age acceleration (EEAA: p < 0.0001 for both), but not intrinsic epigenetic age acceleration (IEAA; p > 0.05 for both). In conclusion, the relationships between LTL and epigenetic clocks were limited to clocks reflecting phenotypic age. The observed association between LTL and EEAA reflects the ability of both measures to detect immunosenescence. The observed modest correlations between LTL and epigenetic clocks highlight a possible benefit from incorporating both measures in understanding disease etiology and prognosis.

RevDate: 2022-05-18

Mota JIS, Silva-Júnior RMP, Martins CS, et al (2022)

Telomeres length and Wnt/β-catenin pathway in adamantinomatous craniopharyngiomas.

European journal of endocrinology pii:EJE-21-1269 [Epub ahead of print].

OBJECTIVES: To evaluate how telomeres length behaves in adamantinomtous craniopharyngioma (aCP) and if it contributes to the pathogenesis of aCPs with and without CTNNB1 mutations.

DESIGN: Retrospective cross-sectional study enrolling 42 aCP patients from two tertiary institutions.

METHODS: Clinicopathological features were retrieved from patient's charts. Fresh frozen tumors were used for RNA and DNA analyses. Telomere length was evaluated by qPCR (T/S ratio). Somatic mutations in TERT promoter (TERTp) and CTNNB1 were detected by Sanger and/or whole-exome sequencing. We performed RNA-Seq to identify differentially expressed genes in aCPs presenting with shorter or longer telomere lengths.

RESULTS: Mutations in CTNNB1 were detected in 29 (69%) tumors. There was higher frequency of CTNNB1 mutations in aCPs from patients diagnosed under the age of 15 years (85% vs 15%; p=0.04) and a trend to recurrent disease (76% vs 24%; p=0.1). No mutation was detected in the TERTp region. The telomeres were shorter in CTNNB1-mutated aCPs (0.441, IQR:0.297-0.597 vs 0.607, IQR:0.445-0.778; p=0.04) but it was neither associated with clinicopathological features nor with recurrence. RNAseq identified a total of 387 differentially expressed genes, generating two clusters, being one enriched for short telomere and CTNNB1-mutated aCPs.

CONCLUSIONS: CTNNB1 mutations are more frequent in children and adolescents and appear to associate with progressive disease. CTNNB1-mutated aCPs have shorter telomeres, demonstrating a relationship between the Wnt/β-catenin pathway and telomere biology in the pathogenesis of aCPs.

RevDate: 2022-05-17

Syreeni A, Carroll LM, Mutter S, et al (2022)

Telomeres do not always shorten over time in individuals with type 1 diabetes.

Diabetes research and clinical practice pii:S0168-8227(22)00740-9 [Epub ahead of print].

AIMS: We aimed to determine how white blood cell (WBC) telomeres and telomere length change over time are associated with health status in type 1 diabetes.

METHODS: Relative telomere length (rTL) was measured in WBC DNA from two time-points (median 6.8 years apart) in 618 individuals from the Finnish Diabetic Nephropathy Study by quantitative PCR, with interassay CV ≤4%.

RESULTS: Baseline rTL correlated inversely with age and was shorter in men. Individuals in the shortest vs. longest rTL tertile had adverse cardiometabolic profiles, worse renal function, and were prescribed more antihypertensive and lipid-lowering drugs. While overall rTL tended to decrease during the median 6.8-years of follow-up, telomeres shortened in 55.3% of subjects, lengthened in 40.0%, and did not change in 4.7%. Baseline rTL correlated inversely with rTL change. Telomere lengthening was associated with higher HDL-Cholesterol (HDL-C), HDL-C/ApoA1, and with antihypertensive drug and (inversely) with lipid-lowering drug commencement during follow-up. Correlates of rTL percentage change per-annum (adjusted model) were baseline BMI, eGFR, previous retinal laser treatment, HDL-C, and HDL-C/ApoA1.

CONCLUSIONS: Telomere length measurements may facilitate the treatment and monitoring of the health status of individuals with type 1 diabetes.

RevDate: 2022-05-16

Tissier ML, Bergeron P, Garant D, et al (2022)

Telomere length positively correlates with pace-of-life in a sex- and cohort-specific way and elongates with age in a wild mammal.

Molecular ecology [Epub ahead of print].

Understanding ageing and the diversity of life histories is a cornerstone in biology. Telomeres, the protecting caps of chromosomes, are thought to be involved in ageing, cancer risks and life-history strategies. They shorten with cell division and age in somatic tissues of most species, possibly limiting lifespan. The resource allocation trade-off hypothesis predicts that short telomeres have thus co-evolved with early reproduction, proactive behaviour and reduced lifespan, i.e. a fast Pace-of-Life Syndrome (POLS). Conversely, since short telomeres may also reduce the risks of cancer, the anti-cancer hypothesis advances that they should be associated with slow POLS. Conclusion on which hypothesis best supports the role of telomeres as mediators of life-history strategies is hampered by a lack of study on wild short-lived vertebrates, apart from birds. Using seven years of data on wild Eastern chipmunks Tamias striatus, we highlighted that telomeres elongate with age (n = 204 and n = 20) and do not limit lifespan in this species (n = 51). Furthermore, short telomeres correlated with a slow POLS in a sex-specific way (n = 37). Females with short telomeres had a delayed age at first breeding and a lower fecundity rate than females with long telomeres, while we found no differences in males. Our findings support most predictions adapted from the anti-cancer hypothesis, but none of those from the resource allocation trade-off hypothesis. Results are in line with an increasing body of evidence suggesting that other evolutionary forces than resource allocation trade-offs shape the diversity of telomere length in adult somatic cells and the relationships between telomere length and life-histories.

RevDate: 2022-05-19

Tang L, Li T, Chang Y, et al (2022)

Diabetic oxidative stress-induced telomere damage aggravates periodontal bone loss in periodontitis.

Biochemical and biophysical research communications, 614:22-28 pii:S0006-291X(22)00562-9 [Epub ahead of print].

Periodontitis, one of the most common oral complications of diabetes mellitus (DM), causes a reduction in alveolar bone height and loss of alveolar bone mass. It has been shown that DM aggravates the progression of periodontitis, but the mechanism remains inconclusive. The hyperglycemic environment of DM has been proven to generate reactive oxygen species (ROS). Since telomeres, guanine-rich repeats, are highly susceptible to oxidative attack, we speculate that the excessive accumulation of ROS in DM could induce telomere damage resulting in dysfunction of periodontal ligament cells, especially periodontal ligament stem cells (PDLSCs), which reduces the ability of tissue repair and reconstruction in diabetic periodontitis. In this study, our current data revealed that oxidative telomere damage occurred in the periodontal ligaments of diabetic mice. And Micro-CT scans showed reduced alveolar bone height and impaired alveolar bone mass in a diabetic periodontitis model. Next, cultured mouse PDLSCs (mPDLSCs) were treated with the oxidant tert-butyl hydroperoxide (t-BHP) in vitro, as we expected telomere damage was observed and resulted in cellular senescence and dysfunction. Taken together, oxidative stress in DM causes telomere dysfunction and PDLSCs senescence, which influences periodontal bone tissue regeneration and reconstruction and ultimately exacerbates bone loss in periodontitis.

RevDate: 2022-05-17

Min J, Kim JY, Choi JY, et al (2022)

Association between Physical Activity and Telomere Length in Women with Breast Cancer: A Systematic Review.

Journal of clinical medicine, 11(9):.

The association between physical activity and telomere length (TL) has been continuously reported. However, the interplay of physical activity and TL among women with breast cancer has not been elucidated. Thus, the purpose of this systematic review was to synthesize the evidence for the association of physical activity with TL in women with breast cancer. Systematic searches were conducted to identify quantified studies using MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Web of Science, and Clinical Five studies were included in this systematic review. Three of the five studies reported that physical activity has a significant relationship in delaying TL shortening, but others observed no association between physical activity and TL in breast cancer survivors. Although the heterogeneous studies acted as limitations in drawing clear conclusions, physical activity strategies show encouraging impacts in delaying TL shortening. To understand the effects of physical activity on TL shortening in breast cancer survivors, further studies are needed considering the tissue site, treatments for breast cancer, DNA extraction methods, and tools for measuring physical activity.

RevDate: 2022-05-16

Kjeldsen E (2022)

Congenital Aneuploidy in Klinefelter Syndrome with B-Cell Acute Lymphoblastic Leukemia Might Be Associated with Chromosomal Instability and Reduced Telomere Length.

Cancers, 14(9): pii:cancers14092316.

Rare congenital aneuploid conditions such as trisomy 13, trisomy 18, trisomy 21 and Klinefelter syndrome (KS, 47,XXY) are associated with higher susceptibility to developing cancer compared with euploid genomes. Aneuploidy frequently co-exists with chromosomal instability, which can be viewed as a "vicious cycle" where aneuploidy potentiates chromosomal instability, leading to further karyotype diversity, and in turn, paving the adaptive evolution of cancer. However, the relationship between congenital aneuploidy per se and tumor initiation and/or progression is not well understood. We used G-banding analysis, array comparative genomic hybridization analysis and quantitative fluorescence in situ hybridization for telomere length analysis to characterize the leukemic blasts of a three-year-old boy with KS and B-cell acute lymphoblastic leukemia (B-ALL), to gain insight into genomic evolution mechanisms in congenital aneuploidy and leukemic development. We found chromosomal instability and a significant reduction in telomere length in leukemic blasts when compared with the non-leukemic aneuploid cells. Reviewing published cases with KS and B-ALL revealed 20 additional cases with B-ALL diagnostic cytogenetics. Including our present case, 67.7% (14/21) had acquired two or more additional chromosomal aberrations at B-ALL diagnosis. The presented data indicate that congenital aneuploidy in B-ALL might be associated with chromosomal instability, which may be fueled by enhanced telomere attrition.

RevDate: 2022-05-17

Kibriya MG, Raza M, Kamal M, et al (2022)

Relative Telomere Length Change in Colorectal Carcinoma and Its Association with Tumor Characteristics, Gene Expression and Microsatellite Instability.

Cancers, 14(9):.

We compared tumor and adjacent normal tissue samples from 165 colorectal carcinoma (CRC) patients to study change in relative telomere length (RTL) and its association with different histological and molecular features. To measure RTL, we used a Luminex-based assay. We observed shorter RTL in the CRC tissue compared to paired normal tissue (RTL 0.722 ± SD 0.277 vs. 0.809 ± SD 0.242, p = 0.00012). This magnitude of RTL shortening (by ~0.08) in tumor tissue is equivalent to RTL shortening seen in human leukocytes over 10 years of aging measured by the same assay. RTL was shorter in cancer tissue, irrespective of age group, gender, tumor pathology, location and microsatellite instability (MSI) status. RTL shortening was more prominent in low-grade CRC and in the presence of microsatellite instability (MSI). In a subset of patients, we also examined differential gene expression of (a) telomere-related genes, (b) genes in selected cancer-related pathways and (c) genes at the genome-wide level in CRC tissues to determine the association between gene expression and RTL changes. RTL shortening in CRC was associated with (a) upregulation of DNA replication genes, cyclin dependent-kinase genes (anti-tumor suppressor) and (b) downregulation of "caspase executor", reducing apoptosis.

RevDate: 2022-05-17

Hou K, Yu Y, Li D, et al (2022)

Alternative Lengthening of Telomeres and Mediated Telomere Synthesis.

Cancers, 14(9):.

Telomeres are DNA-protein complexes that protect eukaryotic chromosome ends from being erroneously repaired by the DNA damage repair system, and the length of telomeres indicates the replicative potential of the cell. Telomeres shorten during each division of the cell, resulting in telomeric damage and replicative senescence. Tumor cells tend to ensure cell proliferation potential and genomic stability by activating telomere maintenance mechanisms (TMMs) for telomere lengthening. The alternative lengthening of telomeres (ALT) pathway is the most frequently activated TMM in tumors of mesenchymal and neuroepithelial origin, and ALT also frequently occurs during experimental cellular immortalization of mesenchymal cells. ALT is a process that relies on homologous recombination (HR) to elongate telomeres. However, some processes in the ALT mechanism remain poorly understood. Here, we review the most recent understanding of ALT mechanisms and processes, which may help us to better understand how the ALT pathway is activated in cancer cells and determine the potential therapeutic targets in ALT pathway-stabilized tumors.

RevDate: 2022-05-18
CmpDate: 2022-05-17

Dratwa M, Wysoczanska B, Brankiewicz W, et al (2022)

Relationship between Telomere Length, TERT Genetic Variability and TERT, TP53, SP1, MYC Gene Co-Expression in the Clinicopathological Profile of Breast Cancer.

International journal of molecular sciences, 23(9):.

The molecular mechanisms of telomerase reverse transcriptase (TERT) upregulation in breast cancer (BC) are complex. We compared genetic variability within TERT and telomere length with the clinical data of patients with BC. Additionally, we assessed the expression of the TERT, MYC, TP53 and SP1 genes in BC patients and in BC organoids (3D cell cultures obtained from breast cancer tissues). We observed the same correlation in the blood of BC patients and in BC organoids between the expression of TERT and TP53. Only in BC patients was a correlation found between the expression of the TERT and MYC genes and between TP53 and MYC. We found associations between TERT genotypes (rs2735940 and rs10069690) and TP53 expression and telomere length. BC patients with the TT genotype rs2735940 have a shorter telomere length, but patients with A allele rs10069690 have a longer telomere length. BC patients with a short allele VNTR-MNS16A showed higher expression of the SP1 and had a longer telomere. Our results bring new insight into the regulation of TERT, MYC, TP53 and SP1 gene expression related to TERT genetic variability and telomere length. Our study also showed for the first time a similar relationship in the expression of the above genes in BC patients and in BC organoids. These findings suggest that TERT genetic variability, expression and telomere length might be useful biomarkers for BC, but their prognostic value may vary depending on the clinical parameters of BC patients and tumor aggressiveness.

RevDate: 2022-05-18
CmpDate: 2022-05-17

Libera V, Bianchi F, Rossi B, et al (2022)

Solvent Vibrations as a Proxy of the Telomere G-Quadruplex Rearrangements across Thermal Unfolding.

International journal of molecular sciences, 23(9):.

G-quadruplexes (G4s) are noncanonical forms of DNA involved in many key genome functions. Here, we exploited UV Resonance Raman scattering to simultaneously explore the vibrational behavior of a human telomeric G4 (Tel22) and its aqueous solvent as the biomolecule underwent thermal melting. We found that the OH stretching band, related to the local hydrogen-bonded network of a water molecule, was in strict relation with the vibrational features of the G4 structure as a function of temperature. In particular, the modifications to the tetrahedral ordering of the water network were strongly coupled to the DNA rearrangements, showing changes in temperature that mirrored the multi-step melting process of Tel22. The comparison between circular dichroism and Raman results supported this view. The present findings provide novel insights into the impact of the molecular environment on G4 conformation. Improving current knowledge on the solvent structural properties will also contribute to a better understanding of the role played by water arrangement in the complexation of G4s with ligands.

RevDate: 2022-05-18
CmpDate: 2022-05-17

Castillo-González C, Barbero Barcenilla B, Young PG, et al (2022)

Quantification of 8-oxoG in Plant Telomeres.

International journal of molecular sciences, 23(9):.

Chemical modifications in DNA impact gene regulation and chromatin structure. DNA oxidation, for example, alters gene expression, DNA synthesis and cell cycle progression. Modification of telomeric DNA by oxidation is emerging as a marker of genotoxic damage and is associated with reduced genome integrity and changes in telomere length and telomerase activity. 8-oxoguanine (8-oxoG) is the most studied and common outcome of oxidative damage in DNA. The G-rich nature of telomeric DNA is proposed to make it a hotspot for oxidation, but because telomeres make up only a tiny fraction of the genome, it has been difficult to directly test this hypothesis by studying dynamic DNA modifications specific to this region in vivo. Here, we present a new, robust method to differentially enrich telomeric DNA in solution, coupled with downstream methods for determination of chemical modification. Specifically, we measure 8-oxoG in Arabidopsis thaliana telomeres under normal and oxidative stress conditions. We show that telomere length is unchanged in response to oxidative stress in three different wild-type accessions. Furthermore, we report that while telomeric DNA comprises only 0.02-0.07% of the total genome, telomeres contribute between 0.2 and 15% of the total 8-oxoG. That is, plant telomeres accumulate 8-oxoG at levels approximately 100-fold higher than the rest of the genome under standard growth conditions. Moreover, they are the primary targets of further damage upon oxidative stress. Interestingly, the accumulation of 8-oxoG in the chromosome body seems to be inversely proportional to telomere length. These findings support the hypothesis that telomeres are hotspots of 8-oxoG and may function as sentinels of oxidative stress in plants.

RevDate: 2022-05-18
CmpDate: 2022-05-17

Pham C, Vryer R, O'Hely M, et al (2022)

Shortened Infant Telomere Length Is Associated with Attention Deficit/Hyperactivity Disorder Symptoms in Children at Age Two Years: A Birth Cohort Study.

International journal of molecular sciences, 23(9):.

Environmental factors can accelerate telomere length (TL) attrition. Shortened TL is linked to attention deficit/hyperactivity disorder (ADHD) symptoms in school-aged children. The onset of ADHD occurs as early as preschool-age, but the TL-ADHD association in younger children is unknown. We investigated associations between infant TL and ADHD symptoms in children and assessed environmental factors as potential confounders and/or mediators of this association. Relative TL was measured by quantitative polymerase chain reaction in cord and 12-month blood in the birth cohort study, the Barwon Infant Study. Early life environmental factors collected antenatally to two years were used to measure confounding. ADHD symptoms at age two years were evaluated by the Child Behavior Checklist Attention Problems (AP) and the Attention Deficit/Hyperactivity Problems (ADHP). Associations between early life environmental factors on TL or ADHD symptoms were assessed using multivariable regression models adjusted for relevant factors. Telomere length at 12 months (TL12), but not at birth, was inversely associated with AP (β = -0.56; 95% CI (-1.13, 0.006); p = 0.05) and ADHP (β = -0.66; 95% CI (-1.11, -0.21); p = 0.004). Infant secondhand smoke exposure at one month was independently associated with shorter TL12 and also higher ADHD symptoms. Further work is needed to elucidate the mechanisms that influence TL attrition and early neurodevelopment.

RevDate: 2022-05-13

Fernandez RJ, Gardner ZJG, Slovik KJ, et al (2022)

GSK3 inhibition rescues growth and telomere dysfunction in dyskeratosis congenita iPSC-derived type II alveolar epithelial cells.

eLife, 11: pii:64430 [Epub ahead of print].

Dyskeratosis congenita (DC) is a rare genetic disorder characterized by deficiencies in telomere maintenance leading to very short telomeres and the premature onset of certain age-related diseases, including pulmonary fibrosis (PF). PF is thought to derive from epithelial failure, particularly that of type II alveolar epithelial (AT2) cells, which are highly dependent on Wnt signaling during development and adult regeneration. We use human iPSC-derived AT2 (iAT2) cells to model how short telomeres affect AT2 cells. Cultured DC mutant iAT2 cells accumulate shortened, uncapped telomeres and manifest defects in the growth of alveolospheres, hallmarks of senescence, and apparent defects in Wnt signaling. The GSK3 inhibitor, CHIR99021, which mimics the output of canonical Wnt signaling, enhances telomerase activity and rescues the defects. These findings support further investigation of Wnt agonists as potential therapies for DC related pathologies.

RevDate: 2022-05-13

Fathi E, Montazersaheb S, Sanaat Z, et al (2022)

L-carnitine reduced cellular aging of bone marrow resident C-kit+ hematopoietic stem cells through telomere dependent pathways.

Current stem cell research & therapy pii:CSCR-EPUB-123378 [Epub ahead of print].

BACKGROUND: Increased oxygen species levels can induce mitochondrial DNA damage and chromosomal aberrations and cause defective stem cell differentiation leading finally to senescence of stem cells. In recent years, several studies have reported that antioxidants can improve stem cell survival and subsequently affect the potency and differentiation of these cells. Finding factors, which reduce the senescence tendency of stem cells upon expansion, has great potential for cellular therapy in regenerative medicine. This study aimed to evaluate the effects of L-carnitine (LC) on the aging of C-kit+ hematopoietic progenitor cells (HPCs) via examining the expression of some signaling pathway components.

METHODS: For this purpose, bone marrow resident C-kit+ HPCs were enriched by the magnetic-activated cell sorting (MACS) method and were characterized using flow cytometry as well as immunocytochemistry. In the following, cells were treated with LC and at the end of the treatment period, the cells were subjected to the real-time PCR technique along with western blotting assay for measurement of the telomere length and assessment of protein expression, respectively.

RESULTS: The results showed that 0.2 mM LC caused the elongation of the telomere length and increased the TERT protein expression. In addition, a significant increase was observed in the protein expression of p38, p53, BCL2, and p16 as key components of the telomere-dependent pathway.

CONCLUSION: It can be concluded that LC can increase the telomere length as an effective factor in increasing the cell survival and maintenance of the C-kit+ HPCs via these signaling pathway components.

RevDate: 2022-05-09

Yang Q, Liu R, Gao Y, et al (2022)

Mediating effect of telomere length in a hypertension population exposed to cadmium: a case-control study.

Journal of human hypertension [Epub ahead of print].

Cadmium (Cd) is associated with telomere length and hypertension, respectively, but the mechanism behind its relationship is unclear. Our study aimed to clarify the role of telomere length in the relationship between Cd and hypertension. A 1:1 matched case-control study was conducted with 213 hypertensive patients and 213 normotensive controls in Taiyuan, Shanxi Province, China, from February and June 2016. General demographic characteristics information and lifestyle were collected using a structured questionnaire. Urine samples were collected to test urinary Cd (UCd) levels and corrected by urinary creatinine (UCr) levels. Peripheral leukocyte absolute telomere length (ATL) was measured using quantitative polymerase chain reaction. Logistic regression was used to screen the influencing factors of hypertension. A mediation effect analysis was used to explore the role of telomere length between Cd exposure and the risk of hypertension. We found that the hypertension group had a significantly higher UCd level compared to the control group (0.91 vs 0.80 μg/g Cr, P < 0.01), while ATL showed the opposite relationship (2.36 vs 2.65 kb, P < 0.01). The Regression analysis of hypertension identified these significant predictors: family history of hypertension (OR = 3.129, 95% confidence interval (95% CI): 1.767-5.540), Body mass index (BMI, OR = 1.088, 95% CI: 1.023-1.157), total cholesterol (TC, OR = 1.277, 95% CI: 1.024-1.592), UCd (OR = 2.092, 95% CI: 1.179-3.710), ATL (OR = 0.105, 95% CI: 0.025-0.453) and 8-hydroxy-2-deoxyguanosine (8-OHdG, OR = 7.864, 95% CI: 3.516-17.589). Mediating effect analysis revealed that ATL was a potential partial mediating factor between Cd and hypertension. Cd may induce hypertension by affecting telomere length, but this requires further exploration.

RevDate: 2022-05-17

Nasiri L, Vaez-Mahdavi MR, Hassanpour H, et al (2022)

Concomitant use of relative telomere length, biological health score and physical/social statuses in the biological aging evaluation of mustard-chemical veterans.

International immunopharmacology, 109:108785 pii:S1567-5769(22)00269-7 [Epub ahead of print].

Sulfur mustard (SM) is a toxic gas that has been used as a chemical weapon in wars. After many years, SM-exposed people are still suffering from its side effects such as biological and premature aging. This study was aimed to evaluate biological aging rate via involving biological health scoring (BHS), relative telomere length (TL) and different physical/social variables i.e. marital and smoking statuses, body mass index, salary and educational levels. BHS was calculated according to measurement of 18 biomarkers related to function of four physiological systems (endocrine, inflammatory, cardiovascular and metabolic systems) and two organs (liver and kidney). The volunteers were 442 individuals exposed to SM gas in 1987 and 119 healthy individuals as non-exposed group. Each group was divided based on leukocyte relative TL (short, intermediate and long). Our data showed an inverse correlation between BHS and relative TL in two groups. The BHS was significantly higher in SM-exposed group than non-exposed group, especially in the participants with short and intermediate TL. The BHS had also a positive correlation with smoking and BMI parameters, and a negative correlation with salary and educational levels in the participants with shorter telomeres; and SM strengthened these correlations in the shorter telomeres. It is concluded that the higher BHS along with shorter relative TL that are indices for lower health quality and biological aging, could be used in the health evaluation of non- and SM-exposed people; and involving of BHS, TL and physical/social covariates could be useful to make this evaluation more accurate.

RevDate: 2022-05-16

Alder JK, M Armanios (2022)

Telomere-mediated Lung Disease.

Physiological reviews [Epub ahead of print].

Parenchymal lung disease is the fourth leading cause of death in the United States; among the top causes, it continues on the rise. Telomeres and telomerase have historically been linked to cellular processes related to aging and cancer, but surprisingly in the recent decade, genetic discoveries have linked the most apparent manifestations of telomere and telomerase dysfunction in humans to the etiology of lung disease: both idiopathic pulmonary fibrosis and emphysema. The short telomere defect is pervasive in a subset of idiopathic pulmonary fibrosis (IPF) patients, and human IPF is the phenotype most intimately tied to germline defects in telomere maintenance. One-third of families with pulmonary fibrosis carries germline mutations in telomerase or other telomere maintenance genes, and one half of patients with apparently sporadic IPF have short telomere length. Beyond explaining genetic susceptibility, short telomere length uncovers clinically relevant syndromic extrapulmonary disease including a T cell immunodeficiency and a propensity to myeloid malignancies. Recognizing this subset of patients who shares a unifying molecular defect has provided a precision medicine paradigm wherein the telomere-mediated lung disease diagnosis provides more prognostic value than histopathology or multi-disciplinary evaluation. Here, we critically evaluate this progress emphasizing how the genetic findings puts forth a new pathogenesis paradigm of age-related lung disease that links telomere abnormalities to alveolar stem senescence, remodeling and defective gas exchange.

RevDate: 2022-05-12

Taub MA, Conomos MP, Keener R, et al (2022)

Genetic determinants of telomere length from 109,122 ancestrally diverse whole-genome sequences in TOPMed.

Cell genomics, 2(1):.

Genetic studies on telomere length are important for understanding age-related diseases. Prior GWAS for leukocyte TL have been limited to European and Asian populations. Here, we report the first sequencing-based association study for TL across ancestrally-diverse individuals (European, African, Asian and Hispanic/Latino) from the NHLBI Trans-Omics for Precision Medicine (TOPMed) program. We used whole genome sequencing (WGS) of whole blood for variant genotype calling and the bioinformatic estimation of telomere length in n=109,122 individuals. We identified 59 sentinel variants (p-value <5×10-9) in 36 loci associated with telomere length, including 20 newly associated loci (13 were replicated in external datasets). There was little evidence of effect size heterogeneity across populations. Fine-mapping at OBFC1 indicated the independent signals colocalized with cell-type specific eQTLs for OBFC1 (STN1). Using a multi-variant gene-based approach, we identified two genes newly implicated in telomere length, DCLRE1B (SNM1B) and PARN. In PheWAS, we demonstrated our TL polygenic trait scores (PTS) were associated with increased risk of cancer-related phenotypes.

RevDate: 2022-05-18

Ferrer A, Mangaonkar AA, MM Patnaik (2022)

Clonal Hematopoiesis and Myeloid Neoplasms in the Context of Telomere Biology Disorders.

Current hematologic malignancy reports, 17(3):61-68.

PURPOSE OF REVIEW: Telomere biology disorders (TBDs) are cancer-predisposing multisystemic diseases that portend a higher risk of transforming into myeloid neoplasms (MNs). Due to the rarity and high variability of clinical presentations, TBD-specific characteristics of MN and the mechanisms behind this predisposition are not well defined. Herein, we review recent studies on TBD patient cohorts describing myeloid transformation events and summarize efforts to develop screening and treatment guidelines for these patients.

RECENT FINDINGS: Preliminary studies have indicated that TBD patients have a higher prevalence of somatic genetic alterations in hematopoietic cells, an age-related phenomenon, also known as clonal hematopoiesis; increasing predisposition to MN. The CH mutational landscape in TBD differs from that observed in non-TBD patients and preliminary data suggest a higher frequency of somatic mutations in the DNA repair mechanism pathway. Although initial studies did not observe specific features of MN in TBD patients, certain events are common in TBD, such as hypocellular bone marrows. The mechanisms of MN development need further elucidation. Current management options for MN-TBD patients need to be individualized and tailored as per the clinical context. Because of the high sensitivity to alkylator chemotherapy and radiation conferred by short telomeres, non-cytotoxic targeted therapies and immunotherapy are ideal therapeutic options, but these therapies are still being tested in clinical trials. Defining the mechanisms of CH evolution in TBD and identifying risk factors leading to MN evolution will allow for the development of screening and treatment guidelines for these patients.

RevDate: 2022-05-05

Shakirov EV, Chen JJ, DE Shippen (2022)

Plant telomere biology: The green solution to the end-replication problem.

The Plant cell pii:6576639 [Epub ahead of print].

Telomere maintenance is a fundamental cellular process conserved across all eukaryotic lineages. Although plants and animals diverged over 1.5 billion years ago, lessons learned from plants continue to push the boundaries of science, revealing detailed molecular mechanisms in telomere biology with broad implications for human health, aging biology, and stress responses. Recent studies of plant telomeres have unveiled unexpected divergence in telomere sequence and architecture, the proteins that engage telomeric DNA and telomerase. The discovery of telomerase RNA components in the plant kingdom and some algae groups revealed new insight into the divergent evolution and the universal core of telomerase across major eukaryotic kingdoms. In addition, resources cataloging the abundant natural variation in Arabidopsis thaliana, maize (Zea mays) and other plants are providing unparalleled opportunities to understand the genetic networks that govern telomere length polymorphism and, as a result, are uncovering unanticipated crosstalk between telomeres, environmental factors, organismal fitness and plant physiology. Here we recap current advances in plant telomere biology and put this field in perspective relative to telomere and telomerase research in other eukaryotic lineages.

RevDate: 2022-05-05

Ujvari B, Raven N, Madsen T, et al (2022)

Telomeres, the loop tying cancer to organismal life-histories.

Molecular ecology [Epub ahead of print].

Recent developments in telomere and cancer evolutionary ecology demonstrate a very complex relationship between the need of tissue repair and controlling the emergence of abnormally proliferating cells. The trade-off is balanced by natural and sexual selection and mediated via both intrinsic and environmental factors. We explore the effects of telomere-cancer dynamics on life history traits and strategies as well as on the cumulative effects of genetic and environmental factors. We show that telomere-cancer dynamics constitute an incredibly complex and a multifaceted process. From research to date, it appears that the relationship between telomere length and cancer risk is likely non-linear with good evidence that both (too) long and (too) short telomeres can be associated with an increased cancer risk. The ability and propensity of organisms to respond to the interplay of telomere dynamics and oncogenic processes, depends on a combination of its tissue environments, life history strategies, environmental challenges (i.e. extreme climatic conditions), pressure by predators and pollution, as well as its evolutionary history. Consequently, precise interpretation of telomere-cancer dynamics requires integrative and multidisciplinary approaches. Finally, incorporating information on telomere dynamics and the expression of tumour suppressor genes and oncogenes could potentially provide the synergistic overview that could lay the foundations to study telomere-cancer dynamics at ecosystem levels.

RevDate: 2022-05-16
CmpDate: 2022-05-04

Panelli DM, Leonard SA, Wong RJ, et al (2022)

Leukocyte telomere dynamics across gestation in uncomplicated pregnancies and associations with stress.

BMC pregnancy and childbirth, 22(1):381.

BACKGROUND: Short leukocyte telomere length is a biomarker associated with stress and morbidity in non-pregnant adults. Little is known, however, about maternal telomere dynamics in pregnancy. To address this, we examined changes in maternal leukocyte telomere length (LTL) during uncomplicated pregnancies and explored correlations with perceived stress.

METHODS: In this pilot study, maternal LTL was measured in blood collected from nulliparas who delivered live, term, singleton infants between 2012 and 2018 at a single institution. Participants were excluded if they had diabetes or hypertensive disease. Samples were collected over the course of pregnancy and divided into three time periods: < 200/7 weeks (Timepoint 1); 201/7 to 366/7 weeks (Timepoint 2); and 370/7 to 9-weeks postpartum (Timepoint 3). All participants also completed a survey assessing a multivariate profile of perceived stress at the time of enrollment in the first trimester. LTL was measured using quantitative polymerase chain reaction (PCR). Wilcoxon signed-rank tests were used to compare LTL differences within participants across all timepoint intervals. To determine whether mode of delivery affected LTL, we compared postpartum Timepoint 3 LTLs between participants who had vaginal versus cesarean birth. Secondarily, we evaluated the association of the assessed multivariate stress profile and LTL using machine learning analysis.

RESULTS: A total of 115 samples from 46 patients were analyzed. LTL (mean ± SD), expressed as telomere to single copy gene (T/S) ratios, were: 1.15 ± 0.26, 1.13 ± 0.23, and 1.07 ± 0.21 for Timepoints 1, 2, and 3, respectively. There were no significant differences in LTL between Timepoints 1 and 2 (LTL T/S change - 0.03 ± 0.26, p = 0.39); 2 and 3 (- 0.07 ± 0.29, p = 0.38) or Timepoints 1 and 3 (- 0.07 ± 0.21, p = 0.06). Participants who underwent cesareans had significantly shorter postpartum LTLs than those who delivered vaginally (T/S ratio: 0.94 ± 0.12 cesarean versus 1.12 ± 0.21 vaginal, p = 0.01). In secondary analysis, poor sleep quality was the main stress construct associated with shorter Timepoint 1 LTLs (p = 0.02) and shorter mean LTLs (p = 0.03).

CONCLUSIONS: In this cohort of healthy pregnancies, maternal LTLs did not significantly change across gestation and postpartum LTLs were shorter after cesarean than after vaginal birth. Significant associations between sleep quality and short LTLs warrant further investigation.

RevDate: 2022-05-04
CmpDate: 2022-05-04

Nickels M, Mastana S, Denniff M, et al (2022)

Pilates and telomere dynamics: A 12-month longitudinal study.

Journal of bodywork and movement therapies, 30:118-124.

Telomeres are dynamic structures that appear to be positively influenced by healthy lifestyle factors such as exercise. Pilates is an increasingly popular exercise modality that is reported to exert beneficial physiological effects in the body, although the cellular mechanisms are poorly understood. The aim of the present study was to investigate the influence of Pilates exercise on telomere length. This longitudinal study followed experienced female Pilates practitioners (n = 11, 50.8 ± 7.5 years) and healthy age- and sex-matched sedentary controls (n = 11, 49.3 ± 6.1 years) over a 12-month period. Leukocyte telomere length was quantified using qPCR. Circulatory inflammatory markers, mRNA gene expression, body composition, physical performance, and mental well-being were also assessed. Telomere length was comparable between Pilates practitioners and controls at baseline (Pre) and 12-months (Post) (p > 0.0125). Pilates practitioners displayed enhanced mRNA gene expression of antioxidant enzymes (SOD2 and GPX1), and lower body fat percentage and visceral fat rating, compared with sedentary controls (p < 0.0125). Over the 12-month longitudinal period, Pilates participants significantly increased dynamic balance (p < 0.05). In conclusion, long-term Pilates participation does not appear to influence telomere length. Nonetheless, Pilates exercise appears to increase antioxidant enzyme gene expression, effectively manage body composition, and improve dynamic balance.

RevDate: 2022-05-02

de Oliveira BCD, Shiburah ME, Paiva SC, et al (2022)

Corrigendum: Possible Involvement of Hsp90 in the Regulation of Telomere Length and Telomerase Activity During the Leishmania Amazonensis Developmental Cycle and Population Proliferation.

Frontiers in cell and developmental biology, 10:894949 pii:894949.

[This corrects the article DOI: 10.3389/fcell.2021.713415.].

RevDate: 2022-05-16

Kirk B, Kuo CL, Xiang M, et al (2022)

Associations between leukocyte telomere length and osteosarcopenia in 20,400 adults aged 60 years and over: Data from the UK Biobank.

Bone, 161:116425 pii:S8756-3282(22)00101-6 [Epub ahead of print].

PURPOSE: Two mechanisms implicated in telomere shortening are oxidative stress and inflammation, both of which are linked to bone and muscle loss suggesting a pathological link between telomere attrition and osteosarcopenia. Using older adults aged 60 years and over in the UK Biobank, we examined the association between leukocyte telomere length and osteosarcopenia.

METHODS: Baseline leukocyte telomere length was measured using a multiplex qPCR technique and expressed as the amount of the telomere amplification product (T) to that of a single-copy gene (S) (T/S ratio). Osteosarcopenia data was from the first imaging visit and defined by WHO criteria (femoral neck bone density T score ≤ -1) for osteopenia/osteoporosis plus either the EWGSOP2 (low appendicular lean mass/height2 and low grip strength) or SDOC (low grip strength and slow walking pace) criteria for sarcopenia. Binary or multinomial logistic regression models were used to associate telomere length and osteosarcopenia or its components, adjusting for the covariates: age, sex, race, education, Townsend deprivation index, alcohol, smoking, BMI/weight, physical activity levels.

RESULTS: Among 20,400 older adults (mean age: 67.79 ± 4.9 years, 53% men), the prevalence of osteosarcopenia by EWGSOP2 (n = 96, 0.47%) or SDOC (n = 205, 1%) criteria was low at the first imaging visit (mean 8.82 years after baseline). Baseline telomere length was not associated with osteosarcopenia by EWGSOP2 (Relative Risk (RR): 1.00, 95% CI: 0.82-1.23 comparing osteosarcopenia to normal (non-osteopenic, non-osteoporotic, and non-sarcopenic) per Standard Deviation (SD) increase in telomere length) or SDOC (RR: 0.95, 95% CI: 0.83-1.09) criteria. Longer telomere length was associated with a lower risk of slow walking pace (Odds Ratio: 0.92, 95% CI: 0.87-0.99 per SD increase in telomere length, p = 0.021). Telomere length, however, was not associated with low grip strength, low bone density or low appendicular lean mass/height2 (p > 0.05).

CONCLUSIONS: In this population-based study, telomere length was not associated with osteosarcopenia; however, slow walking pace was. Further studies are needed to reexamine this relationship, including a greater number of the oldest-old (≥75 years) where osteosarcopenia is more prevalent.

RevDate: 2022-05-03
CmpDate: 2022-05-03

Mikheev RK, Grigoryan OR, Pankratova MS, et al (2022)

[Telomere pathology in ontogenesis in patients with Turner syndrome].

Problemy endokrinologii, 68(2):128-132.

According to present medical databases there many trials to provide in vivo researches in vivo to confirm/refute shortening process of telomeres among patients with Turner syndrome. Despite the successful clinical experience of providing such patients with Turner syndrome, a lot of omics (proteomic and metabolomic) aspects still stay unclear. Main disadvantages of most researches are small volume and minimized mathematical correlation with chronic disease (coronary heart disease, essential hypertension, cardiovascular malformations). Finally, organization of international prospective multi-centered researches in vivo including patients with mosaic cariotype and co-operation between physicians and biologists are optimal solutions for this present problem.

RevDate: 2022-05-03
CmpDate: 2022-05-02

Buemi V, Schillaci O, Santorsola M, et al (2022)

TGS1 mediates 2,2,7-trimethyl guanosine capping of the human telomerase RNA to direct telomerase dependent telomere maintenance.

Nature communications, 13(1):2302.

Pathways that direct the selection of the telomerase-dependent or recombination-based, alternative lengthening of telomere (ALT) maintenance pathway in cancer cells are poorly understood. Using human lung cancer cells and tumor organoids we show that formation of the 2,2,7-trimethylguanosine (TMG) cap structure at the human telomerase RNA 5' end by the Trimethylguanosine Synthase 1 (TGS1) is central for recruiting telomerase to telomeres and engaging Cajal bodies in telomere maintenance. TGS1 depletion or inhibition by the natural nucleoside sinefungin impairs telomerase recruitment to telomeres leading to Exonuclease 1 mediated generation of telomere 3' end protrusions that engage in RAD51-dependent, homology directed recombination and the activation of key features of the ALT pathway. This indicates a critical role for 2,2,7-TMG capping of the RNA component of human telomerase (hTR) in enforcing telomerase-dependent telomere maintenance to restrict the formation of telomeric substrates conductive to ALT. Our work introduces a targetable pathway of telomere maintenance that holds relevance for telomere-related diseases such as cancer and aging.

RevDate: 2022-05-19
CmpDate: 2022-05-02

Ng GY, Hande V, Ong MH, et al (2022)

Effects of dietary interventions on telomere dynamics.

Mutation research. Genetic toxicology and environmental mutagenesis, 876-877:503472.

Telomeres play a critical role in maintaining cellular fate through tight regulation of cell division and DNA damage or repair. Over the years, it is established that biological ageing is defined by a gradual derangement in functionality, productivity, and robustness of biological processes. The link between telomeres and ageing is highlighted when derangement in telomere biology often leads to premature ageing and concomitant accompaniment of numerous age-associated diseases. Unfortunately, given that ageing is a biologically complicated intricacy, measures to reduce morbidity and improve longevity are still largely in the infancy stage. Recently, it was discovered that dietary habits and interventions might play a role in promoting successful healthy ageing. The intricate relationship between dietary components and its potential to protect the integrity of telomeres may provide unprecedented health benefits and protection against age-related pathologies. However, more focused prospective and follow-up studies with and without interventions are needed to unequivocally link dietary interventions with telomere maintenance in humans. This review aims to summarise recent findings that investigate the roles of nutrition on telomere biology and provide enough evidence for further studies to consider the topic of nutrigenomics and its contributions toward healthy ageing and concomitant strategy against age-associated diseases.

RevDate: 2022-05-01
CmpDate: 2022-04-29

Howell MP, Jones CW, Herman CA, et al (2022)

Impact of prenatal tobacco smoking on infant telomere length trajectory and ADHD symptoms at 18 months: a longitudinal cohort study.

BMC medicine, 20(1):153.

BACKGROUND: Prenatal maternal tobacco smoking is a predictor of child attention-deficit/hyperactivity disorder (ADHD) and is associated with offspring telomere length (TL). In this study, we examine the relationship between maternal prenatal smoking, infant TL, and maternal report of early childhood symptoms of ADHD.

METHODS: One-hundred and eighty-one mother-infant dyads were followed prospectively for the infant's first 18 months of life. Prenatal smoking was assessed from maternal report and medical records. TL was measured from infant buccal swab DNA obtained across the first 18 months of life. ADHD symptoms were obtained from maternal report on the Child Behavior Check List. Multiple regression models tested the relation between prenatal smoking and both ADHD symptoms and infant TL. Additional analyses tested whether the change in infant TL influenced the relation between prenatal smoking and ADHD symptoms.

RESULTS: Sixteen percent of mothers reported prenatal smoking. Infant TL at 4, 12, and 18 months of age were correlated. Consistent with previous cross-sectional studies linking shorter offspring TL to maternal prenatal smoking, maternal prenatal smoking predicted greater telomere shortening from four to 18 months of infant age (β = - 5.797, 95% CI [-10.207, -1.386]; p = 0.010). Maternal depression was positively associated with both prenatal smoking (odds ratio (OR): 4.614, 95% CI [1.733, 12.282]; p = 0.002) and child ADHD symptoms (β = 4.713, 95% CI [2.073, 7.354]; p = 0.0006). To prevent confounding, analyses examined the relation between TL, ADHD symptoms, and prenatal smoking only in non-depressed mothers. In non-depressed mothers, infant TL attrition across the first 18 months moderated the relation between smoking and child ADHD.

CONCLUSIONS: The findings extend previous studies linking prenatal smoking to shorter infant TL by providing data demonstrating the effect on TL trajectory. The relation between prenatal smoking and early infant ADHD symptoms was moderated by the change in TL. The findings provide novel initial evidence suggesting that TL dynamics are one mechanistic pathway influencing the relation between maternal prenatal smoking and ADHD.

RevDate: 2022-04-27

Niaz A, Truong JQ, Manoleras A, et al (2022)

Functional interaction between compound heterozygous TERT mutations causes severe telomere biology disorder.

Blood advances pii:485094 [Epub ahead of print].

Telomere biology disorders (TBDs) are a spectrum of multisystem inherited disorders characterized by bone marrow failure, resulting from mutations in genes encoding telomerase or other proteins involved in maintaining telomere length and integrity. Pathogenicity of variants in these genes can be hard to evaluate, since TBD mutations show highly variable penetrance and genetic anticipation due to inheritance of shorter telomeres with each generation. Thus, detailed functional analysis of newly identified variants is often essential. Here we describe a patient with compound heterozygous variants in the TERT gene, which encodes the catalytic subunit of telomerase, hTERT; this patient has the extremely severe Hoyeraal-Hreidarsson form of TBD, although his heterozygous parents are clinically unaffected. Molecular dynamic modeling and detailed biochemical analyses demonstrate that 1 allele (L557P) affects association of hTERT with its cognate RNA component hTR, while the other (K1050E) affects the binding of telomerase to its DNA substrate and enzyme processivity. Unexpectedly, the data demonstrate a functional interaction between the proteins encoded by the 2 alleles, with WT hTERT able to rescue the effect of K1050E on processivity, whereas L557P hTERT cannot. These data contribute to the mechanistic understanding of telomerase, indicating that RNA binding in 1 hTERT molecule affects the processivity of telomere addition by the other molecule. This work emphasizes the importance of functional characterization of TERT variants to reach a definitive molecular diagnosis for TBD patients, and in particular it illustrates the importance of analyzing the effects of compound heterozygous variants in combination to reveal interallelic effects.

RevDate: 2022-04-26

Gentiluomo M, Capurso G, Morelli L, et al (2022)

Genetically determined telomere length is associated with pancreatic neuroendocrine neoplasms onset.

Neuroendocrinology pii:000524659 [Epub ahead of print].

Introduction Telomere length (TL) is a potential indicator of cancer predisposition, however, the multitude of techniques used to measure it causes the results to be heterogeneous and, in some cases, controversial. In the last years, several studies adopted a strategy based on TL associated genetic variants to generate a polygenic score, often referred as teloscore, used in lieu of direct TL measurement. For pancreatic neuroendocrine neoplasms (PanNEN), this strategy has not been attempted yet. Methods A teloscore was generated using 11 SNPs (NAF1-rs7675998, ZNF676-rs409627, TERC-rs10936599, CTC1-rs3027234, PXK-rs6772228, DHX35-rs6028466, OBFC1-rs9420907, ZNF208-rs8105767, ACYP2-rs11125529, TERT-rs2736100 and ZBTB46-rs755017) and 291 PanNEN cases and 1686 controls collected by the PANcreatic Disease ReseArch (PANDoRA) consortium were genotyped to analyse the association of the teloscore and its individual SNPs with the risk of developing PanNEN. Results An association between genetically determined long telomeres and the risk of developing PanNEN (OR=1.99; CI 1.33-2.98; P=0.0008), for highest vs median (third) quintile was observed. In addition, two novel SNPs associated with PanNEN risk were identified: ZNF676-rs409627 (ORC/C_vs_G/G=2.27, CI 1.58-3.27, P=8.80×10-6) and TERT-rs2736100 (ORC/A_vs_C/C=2.03, CI 1.42-2.91, P=1.06×10-4). Conclusion In conclusion, this study provides for the first time a clear indication of the association between long genetically determined telomeres and increased risk of developing PanNEN.

RevDate: 2022-05-05

Yu J, Mathi Kanchi M, Rawtaer I, et al (2022)

Differences between multimodal brain-age and chronological-age are linked to telomere shortening.

Neurobiology of aging, 115:60-69 pii:S0197-4580(22)00066-5 [Epub ahead of print].

Telomere shortening is theorized to accelerate biological aging, however, this has not been tested in the brain and cognitive contexts. We used machine learning age-prediction models to determine brain/cognitive age and quantified the degree of accelerated aging as the discrepancy between brain and/or cognitive and chronological ages (i.e., age gap). We hypothesized these age gaps are associated with telomere length (TL). Using healthy participants from the ADNI-3 cohort (N = 196, Agemean=70.7), we trained age-prediction models using 4 modalities of brain features and cognitive scores, as well as a 'stacked' model combining all brain modalities. Then, these 6 age-prediction models were applied to an independent sample diagnosed with mild cognitive impairment (N = 91, Agemean=71.3) to determine, for each subject, the model-specific predicted age and age gap. TL was most strongly associated with age gaps from the resting-state functional connectivity model after controlling for confounding variables. Overall, telomere shortening was significantly related to older brain but not cognitive age gaps. In particular, functional relative to structural brain-age gaps, were more strongly implicated in telomere shortening.

RevDate: 2022-04-26

Yan M, Cheng S, Wang S, et al (2022)

Association of Genetic Polymorphisms of TERT with Telomere Length in Coke Oven Emissions-Exposed Workers.

International journal of environmental health research [Epub ahead of print].

We explored the association between variations in the telomere maintenance genes and change in telomere length (TL) in workers. The TL of peripheral blood leukocytes from 544 coke oven workers and 238 controls were detected using the Real-time PCR method. Variations in four genes were then detected using the PCR based restriction fragment length polymorphism. The effects of environmental and genetic factors on TL were subsequently analyzed through covariance analysis and a generalized linear model .The TL of subjects with GG genotypes were longer than those with AG genotype in the TERT rs2736098 locus amongst the controls (P = .032). The combined effect of COEs exposure and AG+AA genotypes had a significant effect on TL (P < .001). The interaction between the COEs exposure factor and the rs2736098AG+AA genotypes had a significant effect on the TL (P < .05). The TL in coke oven workers is associated with the interactions between TERT rs2736098 AG+AA and COEs exposure.

RevDate: 2022-04-25

Rohr P, Campanelli Dos Santos I, van Helvoort Lengert A, et al (2022)

Absolute telomere length in peripheral blood lymphocytes of workers exposed to construction environment.

International journal of environmental health research [Epub ahead of print].

Construction environment is composed of various substances classified as carcinogens. Thus, workers exposed in this environment can be susceptible to genomic instability that can be evaluated by absolute telomere length (TL). In this work, we evaluated TL in construction workers compared to a non-exposed group performed by qPCR assay. The TL was evaluated in 59 men exposed to the construction environment (10 years of exposure) and 49 men non-exposed. Our data showed that individuals exposed to the construction environment exhibited a significantly lower TL in relation to non-exposed group (p = 0.009). Also, on the multiple linear regression model, we observed that TL was significantly influenced by the construction environment exposure (p ≤ 0.001). Additionally, the arsenic exposure is associated to a shortening telomere (p ≤ 0.001), and the lead exposure caused an increase in TL (p ≤ 0.001). Thus, our findings suggest a modulation in TL by construction environment exposure, mainly by arsenic and lead exposure.

RevDate: 2022-04-29

Pérez-Martínez L, Wagner T, B Luke (2022)

Telomere Interacting Proteins and TERRA Regulation.

Frontiers in genetics, 13:872636.

Telomere shortening rates inversely correlate with life expectancy and hence it is critical to understand how telomere shortening is regulated. Recently, the telomeric non-coding RNA, TERRA has been implicated in the regulation of replicative senescence. To better understand how TERRA is regulated we employed a proteomics approach to look for potential RNA regulators that associate with telomeric sequences. Based on the results, we have identified proteins that may regulate TERRA in both a positive and negative manner, depending on the state of the telomere. In this mini-review, we discuss and speculate about these data to expand our understanding of TERRA and telomere interactors with respect to telomere shortening dynamics.

RevDate: 2022-05-16

Phillippe M (2022)

Telomeres, oxidative stress, and timing for spontaneous term and preterm labor.

American journal of obstetrics and gynecology pii:S0002-9378(22)00303-9 [Epub ahead of print].

Telomeres are nucleoprotein complexes located at the distal ends of chromosomes. In adults, progressive telomere shortening occurs throughout the lifetime and is thought to contribute to progressive aging, physiological senescence, multiorgan dysfunction, and ultimately, death. As discussed in this review, multiple lines of evidence provide support for the biological plausibility that a telomere-based clock mechanism also determines the length of gestation, leading to the onset of labor (parturition). After telomere expansion at the beginning of pregnancy, the telomere lengths in the gestational tissues (ie, the placenta and fetal membranes) progressively shorten throughout the remainder of pregnancy. The rate of telomere shortening can be accelerated by conditions that affect the mother and result in oxidative stress. Preterm births in the United States are associated with multiple risk factors that are linked with increased oxidative stress. Antioxidant vitamins (ie, vitamins E and C) mitigate the effects of oxidative stress and delay or prevent telomere shortening. Clinical trials with vitamins E and C and with multivitamins started during the periconception period have been associated with reduced rates of preterm births. In the United States, African-American women have a 2-3-fold higher rate of preterm birth. African-American women have multiple risk factors for premature birth, all of which are distinct and potentially additive with regard to epigenetic telomere shortening. The "weathering effect" is the hypothesis to explain the increased rates of chronic illness, disabilities, and early death observed in African-Americans. With regard to pregnancy, accelerated weathering with the associated telomere shortening in the gestational tissues would not only explain the preterm birth disparity but could also explain why highly educated, affluent African-American women continue to have an increased rate of preterm birth. These studies suggest that the racial disparities in preterm birth are potentially mediated by telomere shortening produced by lifetime or even generational exposure to the effects of systemic racism and socioeconomic marginalization. In conclusion, this review presents multiple lines of evidence supporting a novel hypothesis regarding the biological clock mechanism that determines the length of pregnancy, and it opens the possibility of new approaches to prevent or reduce the rate of spontaneous preterm birth.

RevDate: 2022-04-29

Gao X, Yu X, Zhang C, et al (2022)

Telomeres and Mitochondrial Metabolism: Implications for Cellular Senescence and Age-related Diseases.

Stem cell reviews and reports [Epub ahead of print].

Cellular senescence is an irreversible cell arrest process, which is determined by a variety of complicated mechanisms, including telomere attrition, mitochondrial dysfunction, metabolic disorders, loss of protein homeostasis, epigenetic changes, etc. Cellular senescence is causally related to the occurrence and development of age-related disease. The elderly is liable to suffer from disorders such as neurodegenerative diseases, cancer, and diabetes. Therefore, it is increasingly imperative to explore specific countermeasures for the treatment of age-related diseases. Numerous studies on humans and mice emphasize the significance of metabolic imbalance caused by short telomeres and mitochondrial damages in the onset of age-related diseases. Although the experimental data are relatively independent, more and more evidences have shown that there is mutual crosstalk between telomeres and mitochondrial metabolism in the process of cellular senescence. This review systematically discusses the relationship between telomere length, mitochondrial metabolic disorder, as well as their underlying mechanisms for cellular senescence and age-related diseases. Future studies on telomere and mitochondrial metabolism may shed light on potential therapeutic strategies for age-related diseases. Graphical Abstract The characteristics of cellular senescence mainly include mitochondrial dysfunction and telomere attrition. Mitochondrial dysfunction will cause mitochondrial metabolic disorders, including decreased ATP production, increased ROS production, as well as enhanced cellular apoptosis. While oxidative stress reaction to produce ROS, leads to DNA damage, and eventually influences telomere length. Under the stimulation of oxidative stress, telomerase catalytic subunit TERT mainly plays an inhibitory role on oxidative stress, reduces the production of ROS and protects telomere function. Concurrently, mitochondrial dysfunction and telomere attrition eventually induce a range of age-related diseases, such as T2DM, osteoporosis, AD, etc. :increase; :reduce;⟝:inhibition.

RevDate: 2022-05-07

Boniewska-Bernacka E, Pańczyszyn A, Hobot J, et al (2022)

The Length of Leukocyte and Femoral Artery Telomeres in Patients with Peripheral Atherosclerosis.

Genes, 13(4):.

The length of telomeres (TLs) that protect chromosome ends may reflect the age of cells as well as the degree of genetic material damage caused by external factors. Since leukocyte telomere length is associated with cardiovascular diseases, the aim of this study was to evaluate whether leukocyte TL reflects femoral artery wall telomeres of patients with atherosclerosis and lower limb ischemia. Samples of femoral artery wall and blood were collected from 32 patients qualified to surgical revascularization. The analysis included blood and artery wall telomere length measurement and biochemical parameters. The study indicated that there was a moderate correlation between artery wall TL and leukocyte TL. Leukocyte TL was, on average, two times shorter than artery wall TL and correlated with the number of white blood cells. In turn, artery TL was impacted by total cholesterol level. The results suggest that the length of leukocyte telomeres may reflect artery wall TL and indirectly reflect the processes taking place in the artery wall in patients with atherosclerosis.

RevDate: 2022-04-29

Takahashi S, Bhowmik S, Sato S, et al (2022)

Replication Control of Human Telomere G-Quadruplex DNA by G-Quadruplex Ligands Dependent on Solution Environment.

Life (Basel, Switzerland), 12(4):.

The human telomere region is known to contain guanine-rich repeats and form a guanine-quadruplex (G4) structure. As telomeres play a role in the regulation of cancer progression, ligands that specifically bind and stabilize G4 have potential therapeutic applications. However, as the human telomere sequence can form G4 with various topologies due to direct interaction by ligands and indirect interaction by the solution environment, it is of great interest to study the topology-dependent control of replication by ligands. In the present study, a DNA replication assay of a template with a human telomere G4 sequence in the presence of various ligands was performed. Cyclic naphthalene diimides (cNDI1 and cNDI2) efficiently increased the replication stall of the template DNA at G4 with an anti-parallel topology. This inhibition was stability-dependent and topology-selective, as the replication of templates with hybrid or parallel G4 structures was not affected by the cNDI and cNDI2. Moreover, the G4 ligand fisetin repressed replication with selectivity for anti-parallel and hybrid G4 structures without stabilization. Finally, the method used, referred to as quantitative study of topology-dependent replication (QSTR), was adopted to evaluate the correlation between the replication kinetics and the stability of G4. Compared to previous results obtained using a modified human telomere sequence, the relationship between the stability of G4 and the effect on the topology-dependent replication varied. Our results suggest that native human telomere G4 is more flexible than the modified sequence for interacting with ligands. These findings indicate that the modification of the human telomeric sequence forces G4 to rigidly form a specific structure of G4, which can restrict the change in topology-dependent replication by some ligands.

RevDate: 2022-05-18

McGrath SL, Huang SH, K Kobryn (2022)

The N-terminal domain of the Agrobacterium tumefaciens telomere resolvase, TelA, regulates its DNA cleavage and rejoining activities.

The Journal of biological chemistry, 298(5):101951 pii:S0021-9258(22)00391-X [Epub ahead of print].

Linear replicons can be found in a minority of prokaryotic organisms, including Borrelia species and Agrobacterium tumefaciens. The problem with replicating the lagging strand end of linear DNAs is circumvented in these organisms by the presence of covalently closed DNA hairpin telomeres at the DNA termini. Telomere resolvases are enzymes responsible for generating these hairpin telomeres from a dimeric replication intermediate through a two-step DNA cleavage and rejoining reaction referred to as telomere resolution. It was previously shown that the agrobacterial telomere resolvase, TelA, possesses ssDNA annealing activity in addition to telomere resolution activity. The annealing activity derives, chiefly, from the N-terminal domain. This domain is dispensable for telomere resolution. In this study, we used activity analyses of an N-terminal domain deletion mutant, domain add back experiments, and protein-protein interaction studies and we report that the N-terminal domain of TelA is involved in inhibitory interactions with the remainder of TelA that are relieved by the binding of divalent metal ions. We also found that the regulation of telomere resolution by the N-terminal domain of TelA extends to suppression of inappropriate enzymatic activity, including hairpin telomere fusion (reaction reversal) and recombination between replicated telomeres to form a Holliday junction.

RevDate: 2022-04-21

Giha HA, Joatar FE, AlDehaini DMB, et al (2022)

Association of obesity in T2DM with differential polymorphism of ghrelin, growth hormone secretagogue receptor-1 and telomeres maintenance genes.

Hormone molecular biology and clinical investigation pii:hmbci-2021-0063 [Epub ahead of print].

BACKGROUND: Although obesity and T2DM comorbidity is too frequent, the molecular basis of diabetic obesity is largely unexplained and barely investigated.

MATERIALS: Cross-sectional studies were conducted in Kingdom of Saudi Arabia (KSA) in 2013 and Kuwait in 2019. Fasting blood samples were obtained from a total of 216 T2DM patients (104 from KSA) and 193 nondiabetic subjects (93 from KSA) after their consents. Eight SNPs in 5 genes known to be associated with both obesity and T2DM, ghrelin (GHRL) and growth hormone secretagogue receptor -GHSR (KSA) and telomeres maintenance genes (Kuwait) were genotyped by rtPCR. Both patients and controls were grouped into obese and non-obese and sub-grouped into 4-BMI- grades: normal, overweight (OW), obese (OBS) and severely obese (SOBS).

RESULTS: Showed that the only SNP which was distinguished between all groups/subgroups in all study subjects was the ACYP2 rs6713088G/C, where the common CC genotype was under-expressed in the obese compared to non-obese diabetics (17.8% vs. 40.4%, p 0.01) and between the 4-BMI-grade (p 0.025). Interestingly the same genotype was over-expressed in obese compared to non-obese non-diabetics (50% vs. 27.6%, p 0.04). Furthermore, the GHRL (rs27647C/T), GHSR (rs509030G/C) and TERC (rs12696304G/C) MAFs were significantly low in normal BMI patients; p= 0.034, 0.008 and 0.011, respectively.

CONCLUSIONS: This is the first report about the molecular distinction between the obese and non-obese diabetics, it showed the association of rs6713088G/C mutant allele with diabetic obesity, while the GHRL, GHSR and TERC SNPs were differentially expressed based on the BMI-grades.

RevDate: 2022-04-25
CmpDate: 2022-04-25

Wlodarski MW (2022)

The rise of Apollo, protector of telomeres.

Blood, 139(16):2415-2416.

RevDate: 2022-04-29
CmpDate: 2022-04-22

Dempsey PC, Musicha C, Rowlands AV, et al (2022)

Investigation of a UK biobank cohort reveals causal associations of self-reported walking pace with telomere length.

Communications biology, 5(1):381.

Walking pace is a simple and functional form of movement and a strong predictor of health status, but the nature of its association with leucocyte telomere length (LTL) is unclear. Here we investigate whether walking pace is associated with LTL, which is causally associated with several chronic diseases and has been proposed as a marker of biological age. Analyses were conducted in 405,981 UK Biobank participants. We show that steady/average and brisk walkers had significantly longer LTL compared with slow walkers, with accelerometer-assessed measures of physical activity further supporting this through an association between LTL and habitual activity intensity, but not with total amount of activity. Bi-directional mendelian randomisation analyses suggest a causal link between walking pace and LTL, but not the other way around. A faster walking pace may be causally associated with longer LTL, which could help explain some of the beneficial effects of brisk walking on health status. Given its simple measurement and low heritability, self-reported walking pace may be a pragmatic target for interventions.

RevDate: 2022-04-22
CmpDate: 2022-04-22

KrishnaKuchipudi GS, M Prabhu (2022)

Study of Association of Leptin and Leucocyte Telomere Length with Body Mass Index in Adult Indian Population a One Year Cross Sectional Study.

The Journal of the Association of Physicians of India, 70(4):11-12.

Obesity is a leading preventable cause of death and a growing health problem worldwide with increasing rate in both adults and children. Obesity is an important factor causing accelerated aging and various metabolic syndromes. Leptin role as proinflammatory adipokine in obesity is well established. Telomere length acts as a biological clock and a marker for cellular senescence. This study is aimed to quantify leucocyte telomere length & its association with biochemical and anthropometric surrogates of obesity.

MATERIAL: This cross-sectional study was conducted for a duration of 1yr on patients admitted in the wards or attending OPD, fulfilling the inclusion criteria. After a written informed consent and a thorough history, patient's anthropometric measurements were taken following all guidelines. Based on the values obtained the participants were divided into categories based on age and BMI. Blood samples are collected for the assessment of Leucocyte Telomere length through qPCR technique, Leptin through ELIZA method and HBA1c through HPLC method.

OBSERVATION: In our present study, a total of 90 patients were included. These patients are equally divided in age groups of 25-39yrs, 40-54yrs and >=55yrs of age. The mean age of the patients was 48.84±16.84yrs. The patients were further categorized equally in each age group into normal, overweight and obese. The mean BMI of the study subjects was 24.20±3.32 kg/m2. Age is found to have a negative correlation with telomere length (r=-0.205). A significant negative correlation of BMI with telomere length is observed (r=-0.20, p<0.05). No significant correlation between leptin with telomere length (r=0.092, p=0.386) or other anthropometric variables is observed. Waist circumference has a positive correlation with waist/hip ratio (r=0.281) (p=0.007), BMI (r=0.640), weight (r=0.677) and neck circumference(r=0.687). Whereas Telomere length has a negative correlation with waist circumference (r= -0.171), neck circumference (r=--0.2266) (p=0.0318) and positive correlation with waist/hip ratio (r=0.043). In our study a negative correlation was observed between waist/ height ratio and telomere length. Waist hip ratio had a positive correlation with BMI (r= 0.138) and telomere length (r=0.232).

CONCLUSION: Telomere length showed a negative correlation with all anthropometric measures except WHR which showed a positive correlation. Leptin did not show any association with telomere length or anthropometric measures in our study. Our study shows that WHR is a better marker of central obesity than BMI. The notion of metabolically healthy obese also holds true in our study results.

RevDate: 2022-04-20

Lansdorp PM (2022)

Sex differences in telomere length, lifespan, and embryonic dyskerin levels.

Aging cell [Epub ahead of print].

Telomerase levels in most human cells are insufficient to prevent loss of telomeric DNA with each replication cycle. The resulting "Hayflick" limit may have allowed lifespan to increase by suppressing the development of tumors early in life be it at the expense of compromised cellular responses late in life. At any given age, the average telomere length in leukocytes shows considerably variation between individuals with females having, on average, longer telomeres than males. Sex differences in average telomere length are already present at birth and correspond to reported differences in the average life expectancy between the sexes. Levels of telomerase RNA and dyskerin, encoded by DKC1, are known to limit telomerase activity in embryonic stem cells. X-linked DKC1 is expressed from both alleles in female embryo cells and higher levels of dyskerin and telomerase could elongate telomeres prior to embryo implantation. The hypothesis that embryonic telomerase levels set the stage for the sex differences in telomere length and lifespan deserves further study.

RevDate: 2022-05-17
CmpDate: 2022-05-17

Brenner KA, J Nandakumar (2022)

Consequences of telomere replication failure: the other end-replication problem.

Trends in biochemical sciences, 47(6):506-517.

Telomeres are chromosome-capping structures that protect ends of the linear genome from DNA damage sensors. However, these structures present obstacles during DNA replication. Incomplete telomere replication accelerates telomere shortening and limits replicative lifespan. Therefore, continued proliferation under conditions of replication stress requires a means of telomere repair, particularly in the absence of telomerase. It was recently revealed that replication stress triggers break-induced replication (BIR) and mitotic DNA synthesis (MiDAS) at mammalian telomeres; however, these mechanisms are error prone and primarily utilized in tumorigenic contexts. In this review article, we discuss the consequences of replication stress at telomeres and how use of available repair pathways contributes to genomic instability. Current research suggests that fragile telomeres are ultimately tumor-suppressive and thus may be better left unrepaired.

RevDate: 2022-05-12

Chen W, Shi S, Jiang Y, et al (2022)

Association Between Riboflavin Intake and Telomere Length: A Cross-Sectional Study From National Health and Nutrition Examination Survey 1999-2002.

Frontiers in nutrition, 9:744397.

Background: Dietary habits and dietary intake affect telomere length, a reliable marker of biological aging and a predictor of chronic disease. Riboflavin (RF) is known as a water-soluble antioxidant vitamin, but its role in telomere length maintenance has yet to be elucidated.

Objective: The purpose of this study was to examine the relationship between dietary RF intake and telomere length in a nationally representative sample of adults.

Methods: Using the NHANES (1999-2002), telomere data of 4,298 participants aged ≥45 years were analyzed in a cross-sectional manner. Leukocyte telomere length was measured using the quantitative real-time polymerase chain reaction (qPCR). Dietary RF intake was assessed by a trained interviewer using 24-h dietary recall method. Generalized linear regressions were performed to evaluate the association between dietary RF intake and telomere length. Subgroup analyses were performed to further explore this relationship in sex and body mass index (BMI) subgroups.

Results: Among the 3,788 participants included, the average telomere length was longer in females (P = 0.014), while they had a lower average RF intake compared to males (P < 0.001). There was a weak positive correlation between RF intake and telomere length both when unadjusted (β = 0.011; P = 0.037) and adjusted for age, sex, and ethnicity (β = 0.013; P = 0.033). Subgroup analyses showed a positive association between RF intake and the telomere length in female after adjusting for confounding factors (β = 0.029; P = 0.046). In the female subgroup, there were significant positive relationships between telomere length and RF intake in the obese group (β = 0.086, P = 0.022).

Conclusion: Increased dietary RF intake was significantly associated with longer telomere length in middle-aged and older American females, especially in low RF intake obese female.

RevDate: 2022-05-05

Takahashi T, Eguchi A, Watanabe M, et al (2022)

Association between telomere length in human umbilical cord tissues and polychlorinated biphenyls in maternal and cord serum.

Chemosphere, 300:134560 pii:S0045-6535(22)01053-0 [Epub ahead of print].

Environmental exposure to persistent organic pollutants during pregnancy has potential adverse health effects on the fetus. One of the environmental pollutants is polychlorinated biphenyl (PCB). Earlier, we reported the presence of PCBs in fetal tissues such as the umbilical cord. Telomere length (TL) is a biomarker of aging because it shortens with each cell division. According to the Developmental Origins of Health and Disease hypothesis, fetal exposure to environmental pollutants during pregnancy affects the occurrence of non-communicable diseases in later life. In the current study, we investigated the association between cord tissue TL and serum levels of PCBs. The subjects were 114 mother-child pairs participating in a birth cohort study, the Chiba Study of Mother and Child Health (C-MACH). Maternal serum was collected during pregnancy, and cord serum and tissue were obtained at birth. TL was assessed by qPCR using genomic DNA extracted from the cord tissue. Maternal and cord serum PCB congener levels were assessed using gas chromatography and negative ion chemical ionization qMS. In male fetuses, serum levels of PCB74 in the cord blood were significantly associated with TL following covariate adjustment, but no significant association was found in female fetuses. These data suggest that the TL of the umbilical cord is affected by fetal exposure to PCBs.

RevDate: 2022-04-19
CmpDate: 2022-04-18

Muralidharan A, Sotocinal SG, Yousefpour N, et al (2022)

Long-term male-specific chronic pain via telomere- and p53‑mediated spinal cord cellular senescence.

The Journal of clinical investigation, 132(8):.

Mice with experimental nerve damage can display long‑lasting neuropathic pain behavior. We show here that 4 months and later after nerve injury, male but not female mice displayed telomere length (TL) reduction and p53‑mediated cellular senescence in the spinal cord, resulting in maintenance of pain and associated with decreased lifespan. Nerve injury increased the number of p53‑positive spinal cord neurons, astrocytes, and microglia, but only in microglia was the increase male‑specific, matching a robust sex specificity of TL reduction in this cell type, which has been previously implicated in male‑specific pain processing. Pain hypersensitivity was reversed by repeated intrathecal administration of a p53‑specific senolytic peptide, only in male mice and only many months after injury. Analysis of UK Biobank data revealed sex-specific relevance of this pathway in humans, featuring male‑specific genetic association of the human p53 locus (TP53) with chronic pain and a male-specific effect of chronic pain on mortality. Our findings demonstrate the existence of a biological mechanism maintaining pain behavior, at least in males, occurring much later than the time span of virtually all extant preclinical studies.

RevDate: 2022-04-16

S M N Mydin RB, Sreekantan S, Widera D, et al (2022)

Genome-nanosurface interaction of titania nanotube arrays: evaluation of telomere, telomerase and NF-κB activities on an epithelial cell model.

RSC advances, 12(4):2237-2245.

Titanium dioxide nanotube arrays (TNAs) provide a promising platform for medical implants and nanomedicine applications. The present cell-TNA study has provided profound understanding on protection of genome integrity via telomere, telomerase and NF-κB activities using an epithelial cell model. It has been revealed in this study that cell-TNA interaction triggers the telomere shortening activity and inhibition of telomerase activity at the mRNA and protein level. The present work supported that the cell-TNA stimulus might involve controlled transcription and proliferative activities via NBN and TERF21P mechanisms. Moreover, inhibition of NF-κB may promote molecular sensitivity via senescence-associated secretory phenotype activities and might result in reduced inflammatory response which would be good for cell and nanosurface adaptation activities. Thus, this nanomaterial-molecular knowledge is beneficial for further nanomaterial characterization and advanced medical application.

RevDate: 2022-05-19

Zhang X, Cheng S, Li Z, et al (2022)

Telomere length and stroke recurrence after ischemic stroke and TIA.

International journal of stroke : official journal of the International Stroke Society [Epub ahead of print].

BACKGROUND AND OBJECTIVE: Shortening telomere length (TL), as an indicator of aging, has been associated with increased risk of cardiovascular disease and incident stroke. However, there are limited data relating to the association between TL and recurrent stroke.

METHODS: Patients from the Third China National Stroke Registry who had whole genome sequencing (WGS) were selected. TL was estimated using TelSeq based on binary sequence alignment/map files derived from WGS data. Cox proportional hazards regression models were performed to assess the association of TL with recurrent stroke.

RESULTS: A total of 8041 patients with ischemic stroke (IS) or transient ischemic attack (TIA) were included. Mean TL was 2.14 ± 0.82 kb. Patients in the lowest tertile of TL had higher incidence of stroke recurrence compared to those in the middle and highest tertile (6.4% vs 5.9% vs 5.2%), but the difference was not longer significant after adjusting for age, sex, cardiovascular risk factors and stroke severity. Similarly, when analyzing TL as a continuous variable, the HR per 1000 bp increase in TL was significant 0.88 (0.79-0.98), but after adjusting for co-variates, was no longer significant (0.91; 95% confidence interval (CI), 0.81-1.02). In patients aged > 65 years, but not in younger patients, after adjusting for co-variates, TL was significantly associated with stroke recurrence. Compared to the lowest tertile, HRs (95% CI) after adjustment for all co-variates for the middle and highest tertiles were 0.78 (0.55-1.10) and 0.67 (0.46-0.98), respectively, with p for trend of 0.03. In analyses using TL as a continuous variable, adjusted HR (95% CI) per 1000 bp increase in TL was 0.80 (0.66-0.96). However, there was no significant interaction between TL and age on risk of stroke recurrence (p for interaction = 0.09).

CONCLUSIONS: In Chinese IS or TIA patients, no independent association was found between TL and risk of stroke recurrence after adjusting for co-variates. We found a possible association in older patients but this needs replicating.

RevDate: 2022-04-18

Choo S, Lorbeer FK, Regalado SG, et al (2022)

Editing TINF2 as a potential therapeutic approach to restore telomere length in dyskeratosis congenita.

Blood pii:484949 [Epub ahead of print].

Mutations in the TINF2 gene, encoding the shelterin protein TIN2, cause telomere shortening and the inherited bone marrow failure syndrome dyskeratosis congenita (DC). A lack of suitable model systems limits the mechanistic understanding of telomere shortening in the stem cells and thus hinders the development of treatment options for bone marrow failure. Here, we endogenously introduced TIN2-DC mutations in human embryonic stem cells (hESCs) and human hematopoietic stem and progenitor cells (HSPCs) to dissect the disease mechanism and identified a gene editing strategy that rescued the disease phenotypes. The hESCs with the T284R disease mutation exhibited the short telomere phenotype observed in DC patients. Yet, telomeres in mutant hESCs did not trigger DNA damage responses at telomeres or show exacerbated telomere shortening when differentiated into telomerase-negative cells. Disruption of the mutant TINF2 allele by introducing a frameshift mutation in exon 2 restored telomere length in stem cells and the replicative potential of differentiated cells. Similarly, we introduced TIN2-DC disease variants in human HSPCs to assess the changes in telomere length and proliferative capacity. Lastly, we showed that editing at exon 2 of TINF2 that restored telomere length in hESCs could be generated in TINF2-DC patient HSPCs. Our study demonstrates a simple genetic intervention that rescues the TIN2-DC disease phenotype in stem cells and provides a versatile platform to assess the efficacy of potential therapeutic approaches in vivo.

RevDate: 2022-05-07
CmpDate: 2022-04-18

Kelich J, Aramburu T, van der Vis JJ, et al (2022)

Telomere dysfunction implicates POT1 in patients with idiopathic pulmonary fibrosis.

The Journal of experimental medicine, 219(5):.

Exonic sequencing identified a family with idiopathic pulmonary fibrosis (IPF) containing a previously unreported heterozygous mutation in POT1 p.(L259S). The family displays short telomeres and genetic anticipation. We found that POT1(L259S) is defective in binding the telomeric overhang, nuclear accumulation, negative regulation of telomerase, and lagging strand maintenance. Patient cells containing the mutation display telomere loss, lagging strand defects, telomere-induced DNA damage, and premature senescence with G1 arrest. Our data suggest POT1(L259S) is a pathogenic driver of IPF and provide insights into gene therapy options.

RevDate: 2022-04-14

Hoffman TW, van der Vis JJ, Biesma DH, et al (2022)

Extrapulmonary manifestations of a telomere syndrome in patients with idiopathic pulmonary fibrosis are associated with decreased survival.

Respirology (Carlton, Vic.) [Epub ahead of print].

BACKGROUND AND OBJECTIVE: Idiopathic pulmonary fibrosis (IPF) is a heterogenous disease with a median survival of 3-4 years. Patients with mutations in telomere-related genes exhibit extrapulmonary signs and symptoms. These patients represent a distinct phenotype of IPF with worse survival. As genetic analyses are not available for most patients with IPF, we sought to determine the predictive value of extrapulmonary signs and symptoms of a telomere syndrome in patients with IPF.

METHODS: We retrospectively studied 409 patients with IPF. Clinical characteristics, laboratory results and family history suggestive of a telomere syndrome were related to leukocyte telomere length measured by quantitative PCR and patient outcomes.

RESULTS: The cohort included 293 patients with sporadic IPF and 116 patients with a background of familial pulmonary fibrosis. Any or a combination of a clinical history (haematological disease, liver disease, early greying of hair, nail dystrophy, skin abnormalities), a family history or haematological laboratory abnormalities (macrocytosis, anaemia, thrombopenia or leukopenia) suggestive of a telomere syndrome was present in 27% of IPF patients and associated with shorter leukocyte telomere length and shorter survival (p = 0.002 in a multivariate model). In sporadic IPF, having either a clinical history, family history or haematological laboratory abnormalities was not significantly associated with decreased survival (p = 0.07 in a multivariate model).

CONCLUSION: Taking a careful clinical and family history focused on extrapulmonary manifestations of a telomere syndrome can provide important prognostic information in patients with IPF, as this is associated with shorter survival.

RevDate: 2022-05-13
CmpDate: 2022-04-22

Liu B, He Y, Wang Y, et al (2022)

Structure of active human telomerase with telomere shelterin protein TPP1.

Nature, 604(7906):578-583.

Human telomerase is a RNA-protein complex that extends the 3' end of linear chromosomes by synthesizing multiple copies of the telomeric repeat TTAGGG1. Its activity is a determinant of cancer progression, stem cell renewal and cellular aging2-5. Telomerase is recruited to telomeres and activated for telomere repeat synthesis by the telomere shelterin protein TPP16,7. Human telomerase has a bilobal structure with a catalytic core ribonuclear protein and a H and ACA box ribonuclear protein8,9. Here we report cryo-electron microscopy structures of human telomerase catalytic core of telomerase reverse transcriptase (TERT) and telomerase RNA (TER (also known as hTR)), and of telomerase with the shelterin protein TPP1. TPP1 forms a structured interface with the TERT-unique telomerase essential N-terminal domain (TEN) and the telomerase RAP motif (TRAP) that are unique to TERT, and conformational dynamics of TEN-TRAP are damped upon TPP1 binding, defining the requirements for recruitment and activation. The structures further reveal that the elements of TERT and TER that are involved in template and telomeric DNA handling-including the TEN domain and the TRAP-thumb helix channel-are largely structurally homologous to those in Tetrahymena telomerase10, and provide unique insights into the mechanism of telomerase activity. The binding site of the telomerase inhibitor BIBR153211,12 overlaps a critical interaction between the TER pseudoknot and the TERT thumb domain. Numerous mutations leading to telomeropathies13,14 are located at the TERT-TER and TEN-TRAP-TPP1 interfaces, highlighting the importance of TER-TERT and TPP1 interactions for telomerase activity, recruitment and as drug targets.

RevDate: 2022-05-07

Sehl ME, Henry JE, Storniolo AM, et al (2022)

The impact of reproductive factors on DNA methylation-based telomere length in healthy breast tissue.

NPJ breast cancer, 8(1):48.

Estrogen promotes breast tissue proliferation and telomerase activation. We investigated the effects of reproductive history on cell cycling and telomere length using a DNA methylation-based estimate of telomere length (DNAmTL) in breast and blood from healthy women donors. We demonstrate that DNAmTL is shorter in breast than in blood, and that nulliparous women have longer age-adjusted DNAmTL in both breast and blood, potentially explaining their higher risk of breast cancer.

RevDate: 2022-05-16
CmpDate: 2022-05-05

Korkiakoski A, Käräjämäki AJ, Ronkainen J, et al (2022)

Nonalcoholic fatty liver disease and its prognosis associates with shorter leucocyte telomeres in a 21-year follow-up study.

Scandinavian journal of clinical and laboratory investigation, 82(3):173-180.

Leucocyte telomere length (LTL) has been associated with nonalcoholic fatty liver disease (NAFLD), but the evidence is imperfect. Furthermore, liver fibrosis has been shown to correlate with mortality and recent studies have also found associations with LTL and fibrosis suggesting that LTL may have additional prognostic value in liver diseases. Our objective was to study the association of LTL and NAFLD and evaluate the association of LTL in prognosis of NAFLD subjects. Study subjects (n = 847) were middle-aged hypertensive patients. All participants were evaluated for NAFLD and their LTL was measured at baseline. Outcomes were obtained from Finnish Causes-of-Death Register and the Care Register for Health Care in Statistics Finland to the end of 2014. An inverse association with NAFLD prevalence and LTL length was observed (p < .001 for trend). Shortest telomere tertile possessed statistically significantly more NAFLD subjects even with multivariate analysis (shortest vs. middle tertile HR 1.98 p = .006 and shortest vs. longest tertile HR 2.03 p = .007). For the study period, mortality of the study group showed statistically significant relation with telomere length in univariate but not for multivariate analysis. In subgroup analysis, LTL did not associate with prognosis of non-NAFLD subjects. However, LTL was inversely associated with overall mortality in the subjects with NAFLD in both univariate (HR 0.16 p = .007) and multivariate analysis (HR 0.20 p = .045). In middle-aged Caucasian cohort, shorter leucocyte telomeres associated independently with increased prevalence of NAFLD. Shorter LTL was not associated with mortality in non-NAFLD patients whereas it predicted mortality of NAFLD patients independently.

RevDate: 2022-05-03
CmpDate: 2022-04-14

Yamakawa K, Mukai Y, Ye J, et al (2022)

Telomere length was associated with grade and pathological features of meningioma.

Scientific reports, 12(1):6143.

Telomeres are tandem repeats of the TTAGGG sequence at chromosomal ends and afford protection against chromosomal instability. To investigate the contribution of telomere dysfunction in meningiomas, here we estimate the associations between telomere length, tumor grade, and proliferation index in a series of 14 archived samples, using quantitative-fluorescence in situ hybridization, Ki67 immunostaining, and pathological analysis. The number of mitoses per 10 high-power fields (HPF) and Ki67 index was higher in grade III cases than in grade I or grade II cases. Telomere length was negatively associated with both the number of mitoses/10HPF and Ki67 index. Meningioma cases with atypical mitosis, a morphological marker of chromosomal instability, exhibited shortened telomeres. Among telomere-shortened meningioma cases, 40% were grade I, 20% were grade II, and 100% were grade III. In grade I or II meningiomas, shortened telomeres lacked high proliferation activity and atypical mitosis. In conclusion, telomere shortening might be pivotal in the development of high-grade meningioma. Analysis of telomere length might be a selective marker for meningiomas with high-grade malignant potential.

RevDate: 2022-04-12

Ito T, Saeki H, Guo X, et al (2022)

Prenatal stress enhances atherosclerosis and telomere shortening in ApoE knockout mouse offspring.

American journal of physiology. Regulatory, integrative and comparative physiology [Epub ahead of print].

Children born to women who experience stress during pregnancy have an increased risk of atherosclerosis in later life, but few animal models have explored mechanisms. To study this phenomena, timed-bred ApoE knockout mice were determined pregnant with ultrasound and randomly assigned on gestation day 8.5 to either a control (no stress) or prenatal stress (PS) group using two hours of restraint for five consecutive days. PS significantly increased plasma corticosterone levels in pregnant mice. The litters from PS mice showed increased neonatal mortality within the first week of life. Body weights (at euthanasia) of adult offspring at 25 weeks from the PS group were significantly increased compared to weights of controls. Adult offspring from these pregnancies were serially imaged with ultrasound to measure plaque thickness and were compared with plaque macro- and microscopic pathology. PS groups had increased plaques thickness by ultrasound, gross, histological evaluation and increased aortic root and valve macrophage infiltration at 25 weeks. Five-week old mice from PS group had significant decrease in mean arterial pressure, yet blood pressure normalized by 10 weeks. Since prenatal stress induced increased atherosclerosis, and telomeres are susceptible to stress, aortas from 10 week old mice were compared for telomere lengths and were found to be significantly shorter in PS mice compared to control mice. These studies support future investigation of how stress impacts telomere shortening in animal models and human aortas. This model could be further utilized to investigate the role of prenatal stress, telomere biology and atherosclerosis pathogenesis in adults.

RevDate: 2022-04-12

Song L, Wu M, Wang L, et al (2022)

Ambient ozone exposure during pregnancy and telomere length in newborns: a prospective investigation in Wuhan, China.

Environmental science and pollution research international [Epub ahead of print].

Recent studies suggest that environmental exposures, including air pollution, may influence initial (newborn) telomere length (TL), which has important implications for lifetime health. However, the effect of prenatal ozone exposure on newborn TL is unclear. This study aimed to examine the association of ozone exposure during pregnancy with newborn TL. We used data from a birth cohort study of 762 mother-newborn pairs performed in Wuhan, China, during 2013-2015. Land-use regression models were used to assess prenatal ozone exposure. Newborn TL was quantified in cord blood by qPCR assay. We applied multiple informant model to explore the relationship of prenatal ozone exposure with newborn TL. After adjustment for potential confounders, an interquartile range (IQR) increase in ozone exposure during the 2nd trimester, 3rd trimester, and whole pregnancy were associated with 6.00% (95% confidence interval [CI]: 1.59%, 10.62%), 12.64% (95% CI: 7.52%, 18.00%), and 7.10% (95% CI: 4.09%, 10.20%) longer cord blood TL, respectively. In contrast, an IQR increase in ozone exposure during the 1st trimester was associated with a 8.39% (95% CI: - 12.90%, - 3.65%) shorter cord blood TL. In multipollutant models, consistent associations were observed between ozone exposures during the 2nd trimester and whole pregnancy and cord blood TL, but not significant for the 1st and 3rd trimesters. In conclusion, our findings suggest positive associations of ozone exposure during the 2nd trimester, 3rd trimester, and whole pregnancy with newborn TL and a negative association during the 1st trimester. This study provides new evidence in humans for a potential "programming" mechanism linking maternal ozone exposure to the initial (newborn) setting of offspring's telomere biology.

RevDate: 2022-04-15
CmpDate: 2022-04-13

Franzoni LT, Garcia EL, Motta SB, et al (2022)

Aerobic exercise and telomere length in patients with systolic heart failure: protocol study for a randomized controlled trial.

Trials, 23(1):283.

BACKGROUND: Heart failure (HF) with reduced ejection fraction (HFrEF) is a syndrome that leads to fatigue and reduced functional capacity due to disease-related pathophysiological mechanisms. Aerobic exercise (AERO) plays a key role in improving HF outcomes, such as an increase in peak oxygen uptake (VO2peak). In addition, HF promotes cell senescence, which involves reducing telomere length. Several studies have shown that patients with a worse prognosis (i.e., reduced VO2 peak) also have shorter telomeres. However, the effects of AERO on telomere length in patients with HFrEF are still unknown. In an attempt to fill this gap, we designed a study to determine the effects of 16 weeks of aerobic training (32 sessions) on telomere length in HFrEF patients.

METHODS: In this single-center randomized controlled trial, men and women between 50 and 80 years old will be allocated into two different groups: a moderate-intensity aerobic training and a control grouTelomere length, functional capacity, echocardiographic variables, endothelial function, and walking ability will be assessed before and after the 16-week intervention period.

DISCUSSION: Understanding the role of physical exercise in biological aging in HFrEF patients is relevant. Due to cell senescence, these individuals have shown a shorter telomere length. AERO can delay biological aging according to a balance in oxidative stress through antioxidant action. Positive telomere length results are expected for the aerobic training group.

TRIAL REGISTRATION: NCT03856736 . Registered on February 27, 2019.

RevDate: 2022-04-15
CmpDate: 2022-04-13

Vertecchi E, Rizzo A, E Salvati (2022)

Telomere Targeting Approaches in Cancer: Beyond Length Maintenance.

International journal of molecular sciences, 23(7):.

Telomeres are crucial structures that preserve genome stability. Their progressive erosion over numerous DNA duplications determines the senescence of cells and organisms. As telomere length homeostasis is critical for cancer development, nowadays, telomere maintenance mechanisms are established targets in cancer treatment. Besides telomere elongation, telomere dysfunction impinges on intracellular signaling pathways, in particular DNA damage signaling and repair, affecting cancer cell survival and proliferation. This review summarizes and discusses recent findings in anticancer drug development targeting different "telosome" components.

RevDate: 2022-04-21

Yu TN, Cheng EH, Tsai HN, et al (2022)

Assessment of Telomere Length and Mitochondrial DNA Copy Number in Granulosa Cells as Predictors of Aneuploidy Rate in Young Patients.

Journal of clinical medicine, 11(7):.

BACKGROUND: To identify the correlation among female age, cellular aging markers, and aneuploidy rate in in vitro fertilization (IVF) and the preimplantation genetic test for aneuploidy (PGT-A) cycles.

METHODS: This is a prospective cohort study recruiting 110 infertile women between August 2017 and July 2018. They were divided into young-age (<38 years, n = 60) and advanced-age (≥38 years, n = 50) groups. Peripheral leukocytes were assessed, and the granulosa cells were pooled during oocyte pickup. Mitochondrial DNA (mtDNA) copy number and telomere length (TL) were measured using real-time polymerase chain reaction. PGT-A was performed on the NGS platform.

RESULTS: mtDNA copy number and TL were positively correlated in both leukocytes (rho = 0.477, p < 0.001) and granulosa cells (rho = 0.361, p < 0.001), but the two parameters in leukocytes were not correlated with those in granulosa cells. In the young-age group, TL in the granulosa cells was the only factor correlated with the aneuploidy rate (rho = -0.283, p = 0.044), whereas in the advanced-age group, age was the main factor (rho = 0.358, p = 0.018).

CONCLUSIONS: TL in the granulosa cells was negatively correlated with the aneuploidy rate in the young-age group, supporting the application of PGT-A in younger women.

RevDate: 2022-04-13

Pavanello S, Campisi M, Rigotti P, et al (2022)

DNA Methylation - and Telomere - Based Biological Age Estimation as Markers of Biological Aging in Donors Kidneys.

Frontiers in medicine, 9:832411.

The biological age of an organ may represent a valuable tool for assessing its quality, especially in the elder. We examined the biological age of the kidneys [right (RK) and left kidney (LK)] and blood leukocytes in the same subject and compared these to assess whether blood mirrors kidney biological aging. Biological age was studied in n = 36 donors (median age: 72 years, range: 19-92; male: 42%) by exploring mitotic and non-mitotic pathways, using telomere length (TL) and age-methylation changes (DNAmAge) and its acceleration (AgeAcc). RK and LK DNAmAge are older than blood DNAmAge (RK vs. Blood, p = 0.0271 and LK vs. Blood, p = 0.0245) and RK and LK AgeAcc present higher score (this mean the AgeAcc is faster) than that of blood leukocytes (p = 0.0271 and p = 0.0245) in the same donor. TL of RK and LK are instead longer than that of blood (p = 0.0011 and p = 0.0098) and the increase in Remuzzi-Karpinski score is strongly correlated with kidney TL attrition (p = 0.0046). Finally, blood and kidney TL (p < 0.01) and DNAmAge (p < 0.001) were correlated. These markers can be evaluated in further studies as indicators of biological age of donor organ quality and increase the usage of organs from donors of advanced age therefore offering a potential translational research inkidney transplantation.

RevDate: 2022-04-10

Balmori C, Cordova-Oriz I, De Alba G, et al (2021)

Effects of age and oligoasthenozoospermia on telomeres of sperm and blood cells.

Reproductive biomedicine online pii:S1472-6483(21)00524-1 [Epub ahead of print].

RESEARCH QUESTION: How do age and normo- or oligoasthenozoospermia affect telomere length dynamics in spermatozoa and blood?

DESIGN: Sperm and blood samples were collected from a cohort of 37 men aged 25 and under and 40 men aged 40 and over, with either normozoospermia (NZ) or oligoasthenozoospermia (OAZ). Telomere length was evaluated using quantitative fluorescence in-situ hybridization. Telomerase mRNA (TERC and TERT) and shelterin (TRF1) gene expression were analysed using quantitative real-time polymerase chain reaction. TRF1 protein immunoreactivity was also evaluated using immunofluorescence.

RESULTS: Mean sperm telomere length (STL) increased with age in the NZ group; older NZ men accumulated the longest telomeres (P < 0.001). In peripheral blood mononuclear cells (PBMC), mean telomere length decreased with age in NZ groups, although not reaching statistical significance. Interestingly, the younger OAZ group had the shortest mean telomere length (versus young NZ, P = 0.0081; versus old NZ, P = 0.0116; versus old OAZ, P = 0.0009) and accumulated the highest percentage of short telomeres compared with the other groups (overall P = 0.0017). Analysis of TERC and TERT mRNA expression in spermatozoa and PBMC did not show significant differences among groups. Statistically significant positive correlations were found between STL and seminal parameters in younger NZ men (P = 0.009 for sperm count and P = 0.007 for total progressive motility). Protein immunoreactivity of TRF1 in blood was not significantly different in all groups analysed.

CONCLUSIONS: The OAZ group did not show the increase of STL with age that is seen in NZ individuals, suggesting that telomere length elongation mechanisms fail in OAZ patients. In PBMC, younger OAZ individuals showed significantly shorter mean telomere length, suggesting that this parameter could be a good biomarker of OAZ in younger OAZ patients. Telomerase gene and TRF1 mRNA expression and TRF1 protein immunoreactivity did not differ significantly between groups, and so these factors cannot be used as OAZ biomarkers.

RevDate: 2022-04-08

Ayora M, Fraguas D, Abregú-Crespo R, et al (2022)

Leukocyte telomere length in patients with schizophrenia and related disorders: a meta-analysis of case-control studies.

CONTEXT: Telomere length may serve as a biomarker of cellular aging. The literature assessing telomere length in schizophrenia contains conflicting results.

OBJECTIVE: To assess differences in leukocyte telomere length (LTL) in peripheral blood in patients with schizophrenia and related disorders and healthy controls and to explore the effect of potential confounding variables.

DATA SOURCES: A search of Ovid MEDLINE, and Proquest databases was conducted to identify appropriate studies published from database inception through December 2020. The review protocol was registered with PROSPERO-ID: CRD42021233280.

STUDY SELECTION: The initial literature search yielded 192 studies. After study selection in 3 phases, we included 29 samples from 22 studies in the meta-analysis database.

DATA EXTRACTION: We used random effects and meta-regression models to derive Cohen d values with pooled 95% confidence intervals (CI) as estimates of effect size (ES) and to test effects of potential moderators.

RESULTS: The overall meta-analysis included 4145 patients with schizophrenia and related disorders and 4184 healthy controls and showed that LTL was significantly shorter in patients, with a small to medium effect size (ES, -0.388; 95% CI, -0.492 to -0.283; p < 0.001). Subgroup meta-analyses did not find a significant effect of age or illness duration on differences in LTL in patients with psychosis relative to controls. Meta-regression analyses showed that none of the putative moderators had a significant effect on effect size estimates.

CONCLUSIONS: This meta-analysis find further support for the hypothesis of accelerated cellular aging in schizophrenia and related disorders and highlights the need for large longitudinal studies with repeated LTL measurements over time and appropriate assessments of associated factors.

RevDate: 2022-04-09

Córdoba-Lanús E, R Falfán-Valencia (2022)

Editorial: Telomere Dysfunction and Lung Diseases.

Frontiers in medicine, 9:861228.

RevDate: 2022-04-11
CmpDate: 2022-04-11

Tričković JF, Šobot AV, Joksić I, et al (2022)

Telomere fragility in radiology workers occupationally exposed to low doses of ionising radiation.

Arhiv za higijenu rada i toksikologiju, 73(1):23-30 pii:aiht-2022-73-3609.

Ionising radiation damages DNA directly and indirectly through increased production of reactive oxygen species. Although telomeres have been reported as indicators of radiosensitivity, their maintenance in response to occupational exposure to low radiation doses is still a matter of debate. In this work we aimed to investigate telomere length and structure in hospital workers occupationally exposed to X-rays and to relate these findings to oxidation of biomolecules and chromosome aberrations. Blood samples of exposed participants and matching controls were taken during periodical check-ups. Chromosome aberrations and telomere length and structure were analysed in peripheral blood lymphocytes using Q-FISH, whereas oxidative stress parameters [pro/antioxidant balance (PAB), lipid peroxidation, and 8-oxo-dG] were measured in plasma samples. Based on the CA findings we divided the exposed group into two subgroups, of which one had chromosome aberrations in the first division metaphases and the other did not. There was no significant difference in telomere length between any of the groups. However, both subgroups showed significantly higher rate of fragile telomeres and higher lipid peroxidation product and 8-oxo-dG levels than controls. The rate of fragile telomeres significantly correlated with plasma levels of 8-oxo-dG, which suggests that continuous exposure to low radiation doses induces oxidative base damage of guanine resulting in telomere fragility.

RevDate: 2022-05-04

Sakellariou D, Bak ST, Isik E, et al (2022)

MutSβ regulates G4-associated telomeric R-loops to maintain telomere integrity in ALT cancer cells.

Cell reports, 39(1):110602.

Up to 15% of human cancers maintain their telomeres through a telomerase-independent mechanism, termed "alternative lengthening of telomeres" (ALT) that relies on homologous recombination between telomeric sequences. Emerging evidence suggests that the recombinogenic nature of ALT telomeres results from the formation of RNA:DNA hybrids (R-loops) between telomeric DNA and the long-noncoding telomeric repeat-containing RNA (TERRA). Here, we show that the mismatch repair protein MutSβ, a heterodimer of MSH2 and MSH3 subunits, is enriched at telomeres in ALT cancer cells, where it prevents the accumulation of telomeric G-quadruplex (G4) structures and R-loops. Cells depleted of MSH3 display increased incidence of R-loop-dependent telomere fragility and accumulation of telomeric C-circles. We also demonstrate that purified MutSβ recognizes and destabilizes G4 structures in vitro. These data suggest that MutSβ destabilizes G4 structures in ALT telomeres to regulate TERRA R-loops, which is a prerequisite for maintenance of telomere integrity during ALT.

RevDate: 2022-04-21

Nakao T, Bick AG, Taub MA, et al (2022)

Mendelian randomization supports bidirectional causality between telomere length and clonal hematopoiesis of indeterminate potential.

Science advances, 8(14):eabl6579.

Human genetic studies support an inverse causal relationship between leukocyte telomere length (LTL) and coronary artery disease (CAD), but directionally mixed effects for LTL and diverse malignancies. Clonal hematopoiesis of indeterminate potential (CHIP), characterized by expansion of hematopoietic cells bearing leukemogenic mutations, predisposes both hematologic malignancy and CAD. TERT (which encodes telomerase reverse transcriptase) is the most significantly associated germline locus for CHIP in genome-wide association studies. Here, we investigated the relationship between CHIP, LTL, and CAD in the Trans-Omics for Precision Medicine (TOPMed) program (n = 63,302) and UK Biobank (n = 47,080). Bidirectional Mendelian randomization studies were consistent with longer genetically imputed LTL increasing propensity to develop CHIP, but CHIP then, in turn, hastens to shorten measured LTL (mLTL). We also demonstrated evidence of modest mediation between CHIP and CAD by mLTL. Our data promote an understanding of potential causal relationships across CHIP and LTL toward prevention of CAD.

RevDate: 2022-04-19

Cigan SS, Meredith JJ, Kelley AC, et al (2022)

Predicted leukocyte telomere length and risk of germ cell tumours.

British journal of cancer [Epub ahead of print].

BACKGROUND: Genetically predicted leukocyte telomere length (LTL) has been evaluated in several studies of childhood and adult cancer. We test whether genetically predicted longer LTL is associated with germ cell tumours (GCT) in children and adults.

METHODS: Paediatric GCT samples were obtained from a Children's Oncology Group study and state biobank programs in California and Michigan (N = 1413 cases, 1220 biological parents and 1022 unrelated controls). Replication analysis included 396 adult testicular GCTs (TGCT) and 1589 matched controls from the UK Biobank. Mendelian randomisation was used to look at the association between genetically predicted LTL and GCTs and TERT variants were evaluated within GCT subgroups.

RESULTS: We identified significant associations between TERT variants reported in previous adult TGCT GWAS in paediatric GCT: TERT/rs2736100-C (OR = 0.82; P = 0.0003), TERT/rs2853677-G (OR = 0.80; P = 0.001), and TERT/rs7705526-A (OR = 0.81; P = 0.003). We also extended these findings to females and tumours outside the testes. In contrast, we did not observe strong evidence for an association between genetically predicted LTL by other variants and GCT risk in children or adults.

CONCLUSION: While TERT is a known susceptibility locus for GCT, our results suggest that LTL predicted by other variants is not strongly associated with risk in either children or adults.

RevDate: 2022-04-26
CmpDate: 2022-04-26

Anderson JJ, Susser E, Arbeev KG, et al (2022)

Telomere-length dependent T-cell clonal expansion: A model linking ageing to COVID-19 T-cell lymphopenia and mortality.

EBioMedicine, 78:103978.

BACKGROUND: Severe COVID-19 T-cell lymphopenia is more common among older adults and entails poor prognosis. Offsetting the decline in T-cell count during COVID-19 demands fast and massive T-cell clonal expansion, which is telomere length (TL)-dependent.

METHODS: We developed a model of TL-dependent T-cell clonal expansion capacity with age and virtually examined the relation of T-cell clonal expansion with COVID-19 mortality in the general population.

FINDINGS: The model shows that an individual with average hematopoietic cell TL (HCTL) at age twenty years maintains maximal T-cell clonal expansion capacity until the 6th decade of life when this capacity rapidly declines by more than 90% over the next ten years. The collapse in the T-cell clonal expansion capacity coincides with the steep increase in COVID-19 mortality with age.

INTERPRETATION: Short HCTL might increase vulnerability of many older adults, and some younger individuals with inherently short HCTL, to COVID-19 T-cell lymphopenia and severe disease.

FUNDING: A full list of funding bodies that contributed to this study can be found in the Acknowledgements section.

RevDate: 2022-04-29
CmpDate: 2022-04-22

Jin JH, Kwon HS, Choi SH, et al (2022)

Association between sleep parameters and longitudinal shortening of telomere length.

Aging, 14(7):2930-2944.

BACKGROUND: The relationship between sleep parameters and longitudinal shortening of telomere length is unclear. This study aimed to investigate the relationship between sleep parameters and the shortening of leukocyte telomere length (LTL) over a year.

METHODS: Among the participants in the validation cohort of the Korea Brain Aging Study for the Early Diagnosis and Prediction of Alzheimer's Disease, participants who measured both baseline and follow-up (two years later) of LTL were analyzed. They were dichotomized according to the degree of LTL attrition over two years. Clinical characteristics were compared between the faster and slower LTL shortening groups (cut-off points: -0.710 kbp, n = 119 each). Multivariable logistic regression analyses were performed to determine independent relationships between faster shortening of LTL length and sleep parameters.

RESULTS: A total of 238 participants, aged 55-88 years, were included. Participants with faster LTL shortening had a shorter duration of sleep (P = 0.013) and longer sleep latency (P = 0.007). Among the components of the PSQI, subjective measures of sleep quality, sleep latency, sleep duration, and sleep efficiency were significantly worse in participants with faster LTL shortening. Multivariate logistic regression analysis showed that sleep duration (per hour, OR = 0.831, 95% CI = 0.698-0.989), sleep latency (per minute, OR = 1.013, 95% CI = 1.002-1.024), global PSQI score (OR = 1.134, 95% CI = 1.040-1.236), shortest sleep duration (OR = 5.173, 95% CI = 1.563-17.126), and lowest sleep efficiency (OR = 7.351, 95% CI = 1.943-27.946) were independently associated with faster LTL shortening.

CONCLUSIONS: Poor sleep quality, specifically short sleep duration, long sleep latency, and low sleep efficiency were associated with faster longitudinal shortening of LTL.

RevDate: 2022-04-21
CmpDate: 2022-04-05

Spano L, Etain B, Meyrel M, et al (2022)

Telomere length and mitochondrial DNA copy number in bipolar disorder: identification of a subgroup of young individuals with accelerated cellular aging.

Translational psychiatry, 12(1):135.

The 10-15-years decrease in life expectancy observed in individuals with bipolar disorder (BD) has been linked to the concept of accelerated cellular aging. Telomere length (TL) and mitochondrial DNA copy number (mtDNAcn) have been proposed as markers of cellular aging and comparisons between individuals with BD and healthy controls (HC) sometimes led to conflicting results. Previous studies had moderate sample sizes and studies combining these two markers into a single analysis are scarce. Using quantitative polymerase chain reaction, we measured both TL and mtDNAcn in DNA (peripheral blood) in a sample of 130 individuals with BD and 78 HC. Regression analyses, receiver operating characteristic (ROC), and clustering analyses were performed. We observed significantly lower TL and mtDNAcn in individuals with BD as compared to HC (respective decrease of 26.5 and 35.8%). ROC analyses showed that TL and mtDNAcn highly discriminated groups (AUC = 0.904 for TL and AUC = 0.931 for mtDNAcn). In the whole population, clustering analyses identified a group of young individuals (age around 36 years), with accelerated cellular aging (both shorter TL and lower mtDNAcn), which consisted mostly of individuals with BD (85.5%). The subgroup of patients with young age but accelerated aging was not characterized by specific clinical variables related to the course of BD or childhood maltreatment. However, patients in this subgroup were more frequently treated with anticonvulsants. Further characterization of this subgroup is required to better understand the molecular mechanisms and the risk factors of accelerated cellular aging in BD.

RevDate: 2022-04-01

Mc Cartney AM, Shafin K, Alonge M, et al (2022)

Chasing perfection: validation and polishing strategies for telomere-to-telomere genome assemblies.

Nature methods [Epub ahead of print].

Advances in long-read sequencing technologies and genome assembly methods have enabled the recent completion of the first telomere-to-telomere human genome assembly, which resolves complex segmental duplications and large tandem repeats, including centromeric satellite arrays in a complete hydatidiform mole (CHM13). Although derived from highly accurate sequences, evaluation revealed evidence of small errors and structural misassemblies in the initial draft assembly. To correct these errors, we designed a new repeat-aware polishing strategy that made accurate assembly corrections in large repeats without overcorrection, ultimately fixing 51% of the existing errors and improving the assembly quality value from 70.2 to 73.9 measured from PacBio high-fidelity and Illumina k-mers. By comparing our results to standard automated polishing tools, we outline common polishing errors and offer practical suggestions for genome projects with limited resources. We also show how sequencing biases in both high-fidelity and Oxford Nanopore Technologies reads cause signature assembly errors that can be corrected with a diverse panel of sequencing technologies.

RevDate: 2022-04-01

da Silva MS, McCulloch R, MIN Cano (2022)

Editorial: Nuclear Genome Stability: DNA Replication, Telomere Maintenance, and DNA Repair.

Frontiers in cell and developmental biology, 10:875749 pii:875749.

RevDate: 2022-04-05
CmpDate: 2022-04-04

Joseph NA, Chen CF, Chen JH, et al (2022)

Monitoring Telomere Maintenance During Regeneration of Annelids.

Methods in molecular biology (Clifton, N.J.), 2450:467-478.

Telomere shortening is a hallmark of aging and eventually constrains the proliferative capacity of cells. The protocols discussed here are used for monitoring telomeres comprehensively in Aeolosoma viride, a model system for regeneration studies. We present methods for analyzing the activity of telomerase enzyme in regenerating tissue by telomeric repeat amplification protocol (TRAP) assay, for comparing telomere length between existing tissue and newly regenerated tissue by telomere restriction fragment (TRF) assay, as well as for visualizing telomeres by fluorescence in situ hybridization (FISH).

RevDate: 2022-05-12

Hoyt SJ, Storer JM, Hartley GA, et al (2022)

From telomere to telomere: The transcriptional and epigenetic state of human repeat elements.

Science (New York, N.Y.), 376(6588):eabk3112.

Mobile elements and repetitive genomic regions are sources of lineage-specific genomic innovation and uniquely fingerprint individual genomes. Comprehensive analyses of such repeat elements, including those found in more complex regions of the genome, require a complete, linear genome assembly. We present a de novo repeat discovery and annotation of the T2T-CHM13 human reference genome. We identified previously unknown satellite arrays, expanded the catalog of variants and families for repeats and mobile elements, characterized classes of complex composite repeats, and located retroelement transduction events. We detected nascent transcription and delineated CpG methylation profiles to define the structure of transcriptionally active retroelements in humans, including those in centromeres. These data expand our insight into the diversity, distribution, and evolution of repetitive regions that have shaped the human genome.

RevDate: 2022-04-26
CmpDate: 2022-04-26

Nandavaram S, Chandrashekaran S, AE Gelman (2022)

Short telomeres in lung transplantation: Known unknowns.

The Journal of heart and lung transplantation : the official publication of the International Society for Heart Transplantation, 41(5):664-666.

RevDate: 2022-04-29
CmpDate: 2022-04-04

Muoio D, Laspata N, E Fouquerel (2022)

Functions of ADP-ribose transferases in the maintenance of telomere integrity.

Cellular and molecular life sciences : CMLS, 79(4):215.

The ADP-ribose transferase (ART) family comprises 17 enzymes that catalyze mono- or poly-ADP-ribosylation, a post-translational modification of proteins. Present in all subcellular compartments, ARTs are implicated in a growing number of biological processes including DNA repair, replication, transcription regulation, intra- and extra-cellular signaling, viral infection and cell death. Five members of the family, PARP1, PARP2, PARP3, tankyrase 1 and tankyrase 2 are mainly described for their crucial functions in the maintenance of genome stability. It is well established that the most describedrole of PARP1, 2 and 3 is the repair of DNA lesions while tankyrases 1 and 2 are crucial for maintaining the integrity of telomeres. Telomeres, nucleoprotein complexes located at the ends of eukaryotic chromosomes, utilize their unique structure and associated set of proteins to orchestrate the mechanisms necessary for their own protection and replication. While the functions of tankyrases 1 and 2 at telomeres are well known, several studies have also brought PARP1, 2 and 3 to the forefront of telomere protection. The singular quality of the telomeric environment has highlighted protein interactions and molecular pathways distinct from those described throughout the genome. The aim of this review is to provide an overview of the current knowledge on the multiple roles of PARP1, PARP2, PARP3, tankyrase 1 and tankyrase 2 in the maintenance and preservation of telomere integrity.

RevDate: 2022-04-11

Aoulad Fares D, Wiegel RE, Eggink AJ, et al (2022)

Shorter periconception maternal telomere length and the risk of congenital cardiac outflow defects in the offspring.

European journal of clinical investigation [Epub ahead of print].

BACKGROUND: Congenital cardiac outflow defects (COD) are the largest group of congenital heart defects, with ventricular septal defect (VSD) as the most prevalent phenotype. Increased maternal age, excessive oxidative stress and inflammation are involved in the pathophysiology of COD and enhance telomere length (TL) shortening. We investigated the association between periconception maternal TL and the risk of having a child with COD.

METHODS: From a multicentre case-control trial, 306 case mothers of a child with COD and 424 control mothers of a child without a congenital malformation were selected. Relative TL was measured by qPCR. Multivariable logistic regression was used to compute crude and adjusted odds ratios, per standard deviation decrease, between maternal T/S ratio and COD and VSD risk. Adjustments were made for maternal age. Additional adjustments were made in a second model.

RESULTS: Shorter maternal relative TL was significantly associated with an OR of 1.29 (95% CI 1.04-1.61), p = .02, for the risk of VSD in offspring, which remained significant after an adjustment for maternal age (adjOR 1.25(95% CI 1.01-1.55), p = .04). No association between maternal TL and the risk of overall COD in offspring was observed.

CONCLUSION: Shorter maternal relative TL is associated with an approximately 1.3-OR for the risk, per SD in relative TL shortening, of VSD in the offspring. These findings need further confirmation in other studies on the predictive value of maternal TL.

RevDate: 2022-05-13

Gordon CA, Madamanchi NR, Runge MS, et al (2022)

Effect of oxidative stress on telomere maintenance in aortic smooth muscle cells.

Biochimica et biophysica acta. Molecular basis of disease, 1868(7):166397.

Reactive oxygen species (ROS) and telomere dysfunction are both associated with aging and the development of age-related diseases. Although there is evidence for a direct relationship between ROS and telomere dysfunction as well as an independent association of oxidative stress and telomere attrition with age-related disorders, there has not been sufficient exploration of how the interaction between oxidative stress and telomere function may contribute to the pathophysiology of cardiovascular diseases (CVD). To better understand the complex relationships between oxidative stress, telomerase biology and pathophysiology, we examined the telomere biology of aortic smooth muscle cells (ASMCs) isolated from mutant mouse models of oxidative stress. We discovered that telomere lengths were significantly shorter in ASMCs isolated from superoxide dismutase 2 heterozygous (Sod2+/-) mice, which exhibit increased arterial stiffness with aging, and the observed telomere attrition occurred over time. Furthermore, the telomere erosion occurred even though telomerase activity increased. In contrast, telomeres remained stable in wild-type and superoxide dismutase 1 heterozygous (Sod1+/-) mice, which do not exhibit CVD phenotypes. The data indicate that mitochondrial oxidative stress, in particular elevated superoxide levels and decreased hydrogen peroxide levels, induces telomere erosion in the ASMCs of the Sod2+/- mice. This reduction in telomere length occurs despite an increase in telomerase activity and correlates with the onset of disease phenotype. Our results suggest that the oxidative stress caused by imbalance in mitochondrial ROS, from deficient SOD2 activity as a model for mitochondrial dysfunction results in telomere dysfunction, which may contribute to pathogenesis of CVD.

RevDate: 2022-04-10

Zhang Y, Luo S, Jia Y, et al (2022)

Telomere maintenance mechanism dysregulation serves as an early predictor of adjuvant therapy response and a potential therapeutic target in human cancers.

International journal of cancer [Epub ahead of print].

Telomere maintenance mechanisms (TMMs) rescue cells from telomere crisis, endow cells immortal property, stabilize genomic integrity. However, TMM-associated molecular profiles and their clinical outcomes in cancer remain elusive. Here, we performed a pan-cancer and integrated analysis of TMM gene expression profiles from 10 107 unique samples with clinicopathological, molecular and outcome features across seven malignancies from the same microarray platform (Affymetrix GPL570 platform). This resource was divided into case-control datasets for obtaining dysregulated TMM genes and survival datasets for evaluating clinical outcomes. Multidimensional data from The Cancer Genome Atlas (TCGA) were used to elucidate associations between TMM dysregulation and survival, genomic instability. Our results demonstrated that TMMs had a consistent dysregulation spectrum across cancers, based on which we developed the TMM-dysregulation signature TMS score (TMScore) that was positively associated with various tumor adverse features. Two opposite prognostic patterns of TMScore independent of clinicopathological and molecular characteristics were identified, which might be explained by genomic instability: breast and lung cancer patients with elevated TMScore had inferior outcomes, suggesting TMScore-related genes as potential therapeutic targets, on the contrary, colon and stomach cancer patients had superior outcomes. Most important, the prognostic value of TMScore was still significant regardless of whether patients had received adjuvant therapy, which was valuable for discriminating nonresponders from responders, and could predict the effectiveness of adjuvant therapy. In summary, our resources delineate TMMs dysregulated landscape across cancers, shed light on the impact of TMMs dysregulation on patient outcomes and adjuvant therapy, and provide novel therapeutic opportunities for cancer treatment.

RevDate: 2022-05-17
CmpDate: 2022-05-17

Shu MJ, Li J, YC Zhu (2022)

Genetically predicted telomere length and multiple sclerosis.

Multiple sclerosis and related disorders, 60:103731.

BACKGROUND: Previous epidemiological studies have indicated a role for telomere length in multiple sclerosis (MS) severity and phenotype. However, these studies failed to establish the causality between telomere length and MS susceptibility. Hence, we performed two-sample Mendelian randomization (MR) analysis to explore the causal relationship between telomere length and MS susceptibility.

METHODS: We used data of genetic variants associated with leukocyte telomere length as instrumental variables (IVs), which was identified from the largest and latest genome-wide association study (GWAS) from UK Biobank (UKB) with 472,174 participants. Summary data of MS was obtained from the International Multiple Sclerosis Genetics Consortium. We performed two-sample MR analyses using the inverse-variance weighted method as the primary approach. Other MR approaches, including the MR-Egger, the inverse variance weighted (multiplicative random effects), weighted median, simple median, weighted mode-based methods, and Causal Analysis Using Summary Effect estimates (CAUSE), were also conducted to detect the result robustness.

RESULTS: The genetic liability to longer telomere length was associated with a higher risk of MS susceptibility (odds ratio [OR] per one-SD telomere length, 1.91; 95% confidence interval [CI], 1.48-2.47; P = 8.04 × 10-7). The results remained consistent across multiple sensitivity analyses.

CONCLUSIONS: Our study supports the causal relationship between longer telomere length and increased risk of MS susceptibility.

RevDate: 2022-05-11
CmpDate: 2022-05-10

Murkey JA, Watkins BX, Vieira D, et al (2022)

Disparities in allostatic load, telomere length and chronic stress burden among African American adults: A systematic review.

Psychoneuroendocrinology, 140:105730.

BACKGROUND: The chronic disease burden among African Americans has continued to rise. Although racial disparities in chronic disease risk are well documented, the role of chronic stress in risk disparities among racial and ethnic minorities is not well understood. This systematic review of studies reporting on the relationship between chronic stress, education, and/or income, and biomarkers of chronic stress (allostatic load and telomere length) longitudinally among African Americans, seeks to contribute to this knowledge gap.

OBJECTIVE: To use the existing literature to both examine the strength of two objective biomarkers--telomere length and allostatic load--as measures of the overactivation of physiological stress processes in African American adults; and determine if existing studies used these two biomarkers to assess the relationship between chronic stress, income and level of educational attainment among African Americans longitudinally.

METHODS: In order to identify English-language articles published prior to October 11, 2021, a comprehensive search strategy was developed using five databases: PubMed/Medline, EMBASE, Web of Science Plus, Global Health (Ovid), and PsycINFO. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method was used to record progress on the comprehensive search for studies reporting on allostatic load and/or telomere length biomarkers longitudinally within all bodily fluids and chronic stress among African American adults.

RESULTS: In total, 7 studies met the search criteria; 902 were excluded. Thus, less than 1% of all studies reporting on biomarkers of chronic stress longitudinally included African Americans. Each of the 7 studies described the relationship between telomere length and/or allostatic load among African Americans and chronic stress, education, and/or income. Higher chronic stress levels and experiences of racial discrimination were associated with telomere shortening while lower income and higher chronic stress levels were associated with an increase in allostatic load among African Americans.

DISCUSSION: Given the limited number of studies reporting on the association between allostatic load, telomere length, and/or the relationship between both in assessing chronic stress severity longitudinally among African American populations, it is impossible to determine whether one biomarker has greater predictive value than the other. However, based on the literature included in this review, higher chronic stress levels and experiences of racial discrimination were associated with shorter telomere length, while lower income and higher chronic stress levels are associated with an increase in allostatic load among African Americans.

CONCLUSION: These data illustrate a gap in the literature on the relationship between the biomarkers of telomere length and allostatic load combined as a potential measure for chronic stress among African Americans. To our knowledge, none the current literature describes the relationship between telomere length and allostatic load longitudinally among African American adults. As the field strives to develop a "gold standard" for measuring chronic stress, the combination of these biomarkers needs to be the subject of scientific inquiry and thus, fully examined. Future longitudinal studies among African Americans are needed to better understand which biomarker, or combination of biomarkers will provide the most accurate measure of physiological stress processes.

RevDate: 2022-04-08

Navrátilová P, Toegelová H, Tulpová Z, et al (2022)

Prospects of telomere-to-telomere assembly in barley: Analysis of sequence gaps in the MorexV3 reference genome.

Plant biotechnology journal [Epub ahead of print].

The first gapless, telomere-to-telomere (T2T) sequence assemblies of plant chromosomes were reported recently. However, sequence assemblies of most plant genomes remain fragmented. Only recent breakthroughs in accurate long-read sequencing have made it possible to achieve highly contiguous sequence assemblies with a few tens of contigs per chromosome, that is a number small enough to allow for a systematic inquiry into the causes of the remaining sequence gaps and the approaches and resources needed to close them. Here, we analyse sequence gaps in the current reference genome sequence of barley cv. Morex (MorexV3). Optical map and sequence raw data, complemented by ChIP-seq data for centromeric histone variant CENH3, were used to estimate the abundance of centromeric, ribosomal DNA, and subtelomeric repeats in the barley genome. These estimates were compared with copy numbers in the MorexV3 pseudomolecule sequence. We found that almost all centromeric sequences and 45S ribosomal DNA repeat arrays were absent from the MorexV3 pseudomolecules and that the majority of sequence gaps can be attributed to assembly breakdown in long stretches of satellite repeats. However, missing sequences cannot fully account for the difference between assembly size and flow cytometric genome size estimates. We discuss the prospects of gap closure with ultra-long sequence reads.

RevDate: 2022-04-18
CmpDate: 2022-04-18

Praveen G, Sivaprasad M, GB Reddy (2022)

Telomere length and vitamin B12.

Vitamins and hormones, 119:299-324.

Telomeres are non-coding nucleoprotein structures consisting of a highly conserved tandem repeat DNA sequence that caps the ends of chromosomes in eukaryotes. Telomeres confer chromosomal stability, protect the genome from nucleolytic degradation, avoid aberrant recombination and improper repair, and prevent random fusion of chromosomes. The end-replication problem results in telomere shortening with every cell division, eventually leading to cellular senescence and aging. Telomere length (TL) is thereby an ideal candidate for "biological aging." Telomeres possess guanine-rich repeats, which are highly susceptible to oxidative stress. Epidemiological studies have indicated the association of telomere attrition with mortality and various age-related diseases. Micronutrients comprising vitamins and minerals act as potential modulators of stress and can influence TL. Research has indicated that vitamin B12 (B12) regulates oxidative stress and maintains genomic stability, thereby influencing telomere integrity and cellular aging. The deficiency of B12 leads to elevated levels of homocysteine, which reduces the methylation potential and increases oxidative stress, thereby compromising the TL. Telomere shortening and mitochondrial dysfunction are independently linked to aging. However, they are connected through telomerase reverse transcriptase activity, which regulates mitochondrial biogenesis. Further, experimental evidence indicated the positive association of B12 with relative TL and mitochondrial DNA copy number, an indirect index of mitochondrial biogenesis. The present chapter provides some insights into the role of B12 in influencing TL. Exploring their association might open new avenues to understand the pathophysiology of aging and age-related diseases.

RevDate: 2022-04-01
CmpDate: 2022-03-31

Wan S, Zhao X, Pei J, et al (2022)

Association of age at benign hysterectomy with leukocyte telomere length in a nationally representative population.

Maturitas, 159:46-51.

OBJECTIVES: Hysterectomy is one of the most common gynecological surgical procedures, and most hysterectomies are performed for benign indications. Despite the frequency and known benefits of the procedure, it remains unclear whether it has potential adverse effects on long-term health and longevity. The aim of this study was to evaluate the association of age at benign hysterectomy with leukocyte telomere length, in data from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2002.

STUDY DESIGN: In total, 811 women who had a hysterectomy were included in this cross-sectional study.

MAIN OUTCOME MEASURES: To estimate the association of age at benign hysterectomy with telomere length, multivariate regression analyses adjusted for age, race/ ethnicity, education, marital status, income poverty ratio, body mass index (BMI), physical activity, smoking behavior, alcohol consumption, history of chronic disease and history of oophorectomy were conducted. Fitted smoothing curves were also evaluated.

RESULTS: We found leukocyte telomere length was positively correlated with age at benign hysterectomy after adjusting for other confounders in both a minimally adjusted model [β = 4.18, 95%CI: (0.17,8.20)] and a fully adjusted model [β = 4.63, 95% CI:(0.56,8.70)].

CONCLUSIONS: Earlier age at benign hysterectomy was associated with shorter telomere length in a nationally representative population of women. These data provide new information in pre-surgical counseling and decision-making.


ESP Quick Facts

ESP Origins

In the early 1990's, Robert Robbins was a faculty member at Johns Hopkins, where he directed the informatics core of GDB — the human gene-mapping database of the international human genome project. To share papers with colleagues around the world, he set up a small paper-sharing section on his personal web page. This small project evolved into The Electronic Scholarly Publishing Project.

ESP Support

In 1995, Robbins became the VP/IT of the Fred Hutchinson Cancer Research Center in Seattle, WA. Soon after arriving in Seattle, Robbins secured funding, through the ELSI component of the US Human Genome Project, to create the original ESP.ORG web site, with the formal goal of providing free, world-wide access to the literature of classical genetics.

ESP Rationale

Although the methods of molecular biology can seem almost magical to the uninitiated, the original techniques of classical genetics are readily appreciated by one and all: cross individuals that differ in some inherited trait, collect all of the progeny, score their attributes, and propose mechanisms to explain the patterns of inheritance observed.

ESP Goal

In reading the early works of classical genetics, one is drawn, almost inexorably, into ever more complex models, until molecular explanations begin to seem both necessary and natural. At that point, the tools for understanding genome research are at hand. Assisting readers reach this point was the original goal of The Electronic Scholarly Publishing Project.

ESP Usage

Usage of the site grew rapidly and has remained high. Faculty began to use the site for their assigned readings. Other on-line publishers, ranging from The New York Times to Nature referenced ESP materials in their own publications. Nobel laureates (e.g., Joshua Lederberg) regularly used the site and even wrote to suggest changes and improvements.

ESP Content

When the site began, no journals were making their early content available in digital format. As a result, ESP was obliged to digitize classic literature before it could be made available. For many important papers — such as Mendel's original paper or the first genetic map — ESP had to produce entirely new typeset versions of the works, if they were to be available in a high-quality format.

ESP Help

Early support from the DOE component of the Human Genome Project was critically important for getting the ESP project on a firm foundation. Since that funding ended (nearly 20 years ago), the project has been operated as a purely volunteer effort. Anyone wishing to assist in these efforts should send an email to Robbins.

ESP Plans

With the development of methods for adding typeset side notes to PDF files, the ESP project now plans to add annotated versions of some classical papers to its holdings. We also plan to add new reference and pedagogical material. We have already started providing regularly updated, comprehensive bibliographies to the ESP.ORG site.

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Good Beginner's Books

Although multicellular eukaryotes (MCEs) are the most visible component of the biosphere, they represent a highly derived and constrained evolutionary subset of the biosphere, unrepresentative of the vast, mostly unseen, microbial world of prokaryotic life that comprises at least half of the planet's biomass and most of its genetic diversity. The existence of telomeres is one component of the specialized biology of eukaryotes. R. Robbins

Electronic Scholarly Publishing
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Papers in Classical Genetics

The ESP began as an effort to share a handful of key papers from the early days of classical genetics. Now the collection has grown to include hundreds of papers, in full-text format.

Digital Books

Along with papers on classical genetics, ESP offers a collection of full-text digital books, including many works by Darwin (and even a collection of poetry — Chicago Poems by Carl Sandburg).


ESP now offers a much improved and expanded collection of timelines, designed to give the user choice over subject matter and dates.


Biographical information about many key scientists.

Selected Bibliographies

Bibliographies on several topics of potential interest to the ESP community are now being automatically maintained and generated on the ESP site.

ESP Picks from Around the Web (updated 07 JUL 2018 )