Telomeres In Cells Research Articles

P-175 Human cumulus cell telomere length and its association with assisted reproduction outcomes

Abstract Study question Is there any relationship between the relative telomere length (RTL) within cumulus cells (CCs) and the outcome of assisted reproductive treatment using the corresponding oocyte? Summary answer Lower RTLs in CCs were significantly associated with embryos chosen for transfer or cryopreservation. In contrast, embryos considered non-viable (discarded) tended to have higher RTLs. What is known already Cumulus cells fulfil vital roles in support of oocyte development, including the transduction of external signals and the provision of resources via transzonal projections. Given their essential role in the acquisition of oocyte developmental competence, the biology of CCs is of clinical relevance. Telomeres are specialised structures protecting the ends of chromosomes, composed of repetitive DNA sequences and associated proteins. Telomeres shorten with each mitotic division, as well as due to oxidative damage, eventually reaching a critical threshold at which point cellular senescence occurs. Currently, published data on CCs telomere length and relationship with oocyte potential are conflicting. Study design, size, duration The study involved 182 human CC samples collected from 52 IVF patients. Quantitative PCR (qPCR) was used to measure the relative telomere length in each of the CC samples. Telomere lengths were assessed for associations with various patient characteristics (e.g. age, body mass index, infertility diagnosis). Additionally, potential relationships with clinically relevant oocyte/embryo features were investigated (fertilisation; development/morphology), as well as the eventual fate of the associated embryo (transferred; cryopreserved for potential future use; discarded). Participants/materials, setting, methods Real-time quantitative PCR was carried out using PCR primers specific for the telomere repeat. A single-copy gene was also amplified from each CC sample. Quantification of this gene was used for normalisation of the telomere data, allowing control for variation in the number of cumulus cells in each sample. Associations between RTL in CCs and patient, embryonic, and clinical factors were assessed using various statistical methods, with P-values <0.05 considered significant. Main results and the role of chance No associations were identified between RTL and any patient characteristics, except for BMI. The amount of CC telomeric DNA tended to be greater for patients with higher BMI (P = 0.002). When considering links between RTL and oocyte or embryonic factors, a significant relationship was detected between the quantity of telomeric DNA in CCs and whether the corresponding embryo was considered non-viable (discarded) or whether it was transferred or cryopreserved (P = 0.019). This finding raises the possibility that measurement of RTL in CCs could provide a pre-conception, non-invasive assessment of oocyte quality. In the context of fertility preservation, RTL measurement could assist in evaluating a cohort of oocytes, indicating whether the cryopreserved eggs are likely to be sufficient or whether additional cycles to generate more would be advisable. If future studies confirm that CC RTL has a strong predictive value, the possibility of limiting fertilisation to oocytes considered to have high likelihood of viability could also be considered for routine IVF cycles. It is unclear why shorter CC telomeres might be associated with oocytes of superior potential, but one possibility is that the cells may have undergone a greater proliferation (more mitoses), resulting in a more extensive cumulus mass supporting the enclosed oocyte. Limitations, reasons for caution Before drawing definitive conclusions, confirmation of the findings within a larger, independent data set is necessary. Even if confirmed, determination of the true clinical value of telomere assessment will require further, appropriately designed studies. The current study was not powered to evaluate relationships between CC telomere lengths and IVF outcomes. Wider implications of the findings Currently, simplistic morphological evaluation is the only method for assessing oocyte competence prior to fertilisation. If CCs telomere measurement is confirmed to have predictive value, a preconception test of oocyte potential could be offered. This would be extremely valuable for patients cryopreserving oocytes for fertility preservation and for donor banks. Trial registration number NA

Telomere Length in Human Spermatogenic Cells as a New Potential Predictor of Clinical Outcomes in ART Treatment with Intracytoplasmic Injection of Testicular Spermatozoa.

Predicting the clinical outcomes of intracytoplasmic sperm injection (ICSI) cycles that use the testicular spermatozoa of azoospermic patients presents a challenge. Thus, the development of additional approaches to assessing the competence of a testicular-sperm-derived embryo without causing damage to gametes or the embryo is necessary. One of the key parameters in determining such developmental competence is telomere length (TL). We aimed to analyze TLs in spermatogenic cells from the testicular biopsy samples of azoospermic patients and determine how this parameter influences embryo competence for pre- and post-implantation development. Using Q-FISH, we studied the TL of the chromosomes in spermatogonia and spermatocytes I from the TESE biopsy samples of 30 azoospermic patients. An increase in TL was detected during the differentiation from spermatogonia to spermatocytes I. The patients' testicular spermatozoa were used in 37 ICSI cycles that resulted in 22 embryo transfers. Nine pregnancies resulted, of which, one was ectopic and eight ended in birth. The analysis of embryological outcomes revealed a dependence between embryo competence for development to the blastocyst stage and the TL in spermatogenic cells. The TLs in spermatogonia and spermatocytes I in the testicular biopsy samples were found to be higher in patients whose testicular sperm ICSI cycles resulted in a birth. Therefore, the length of telomeres in spermatogenic cells can be considered as a potential prognostic criterion in assessing the competence of testicular-sperm-derived embryos for pre- and post-implantation development. The results of this study provide the basis for the development of a laboratory test for the prediction of testicular sperm ICSI cycle outcomes.

Short telomeres in alveolar type II cells associate with lung fibrosis in post COVID-19 patients with cancer.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the coronavirus disease 2019 (COVID-19) pandemic. The severity of COVID-19 increases with each decade of life, a phenomenon that suggest that organismal aging contributes to the fatality of the disease. In this regard, we and others have previously shown that COVID-19 severity correlates with shorter telomeres, a molecular determinant of aging, in patient's leukocytes. Lung injury is a predominant feature of acute SARS-CoV-2 infection that can further progress to lung fibrosis in post-COVID-19 patients. Short or dysfunctional telomeres in Alveolar type II (ATII) cells are sufficient to induce pulmonary fibrosis in mouse and humans. Here, we analyze telomere length and the histopathology of lung biopsies from a cohort of alive post-COVID-19 patients and a cohort of age-matched controls with lung cancer. We found loss of ATII cellularity and shorter telomeres in ATII cells concomitant with a marked increase in fibrotic lung parenchyma remodeling in post- COVID-19 patients compared to controls. These findings reveal a link between presence of short telomeres in ATII cells and long-term lung fibrosis sequel in Post-COVID-19 patients.

A Lens on Caregiver Stress in Cancer: Longitudinal Investigation of Cancer-Related Stress and Telomere Length Among Family Caregivers of Adult Patients With Cancer.

Family members are typically the primary caregivers of patients with chronic illnesses. Family caregivers of adult relatives with cancer are a fast-growing population, yet the physical consequences of their stress due to the cancer in the family have been poorly understood. This study examined the bidirectional relations of the perceived stress of family caregivers of individuals recently diagnosed with cancer and leukocyte cellular aging indexed by telomere length for 2 years. Family caregivers ( N = 168; mean age = 51 years, 70% female, 46% Hispanic, 36% spouse to the patient) of patients with colorectal cancer provided psychological data and peripheral blood samples approximately 4 (T1), 12 (T2), and 21 months (T3) after diagnosis. Time-lagged cross-panel modeling was used to test the associations of perceived cancer-related stress and telomere length, controlling for age, sex, and body mass index. Cancer-related stress was highest at T1 and decreased by 1 year. Greater cancer-related stress predicted longer telomere length at subsequent assessments for 2 years ( β ≥ 0.911, p ≤ .019). However, telomere length did not change significantly for 2 years overall and did not prospectively predict cancer-related stress over this period. Findings suggest the need to better understand how the perceived stress of colorectal cancer caregivers, which tends to be intense for a relatively short period compared with dementia caregiving, may impact immune cell distributions and telomere length. These findings emphasize the need for further knowledge about psychobiological mechanisms of how cancer caregiving may impact cellular aging.

Endothelial cell telomere dysfunction induces senescence and results in vascular and metabolic impairments.

In advanced age, increases in oxidative stress and inflammation impair endothelial function, which contributes to the development of cardiovascular disease (CVD). One plausible source of this oxidative stress and inflammation is an increase in the abundance of senescent endothelial cells. Cellular senescence is a cell cycle arrest that occurs in response to various damaging stimuli. In the present study, we tested the hypothesis that advanced age results in endothelial cell telomere dysfunction that induces senescence. In both human and mouse endothelial cells, advanced age resulted in an increased abundance of dysfunctional telomeres, characterized by activation of DNA damage signaling at telomeric DNA. To test whether this results in senescence, we selectively reduced the telomere shelterin protein telomere repeat binding factor 2 (Trf2) from endothelial cells of young mice. Trf2 reduction increased endothelial cell telomere dysfunction and resulted in cellular senescence. Furthermore, induction of endothelial cell telomere dysfunction increased inflammatory signaling and oxidative stress, resulting in impairments in endothelial function. Finally, we demonstrate that endothelial cell telomere dysfunction-induced senescence impairs glucose tolerance. This likely occurs through increases in inflammatory signaling in the liver and adipose tissue, as well as reductions in microvascular density and vasodilation to metabolic stimuli. Cumulatively, the findings of the present study identify age-related telomere dysfunction as a mechanism that leads to endothelial cell senescence. Furthermore, these data provide compelling evidence that senescent endothelial cells contribute to age-related increases in oxidative stress and inflammation that impair arterial and metabolic function.

Mono-(2-ethylhexyl) Phthalate (MEHP)-Induced Telomere Structure and Function Disorder Mediates Cell Cycle Dysregulation and Apoptosis via c-Myc and Its Upstream Transcription Factors in a Mouse Spermatogonia-Derived (GC-1) Cell Line.

As a typical environmental endocrine disrupting chemical (EDC), di-(2-ethylhexyl) phthalate (DEHP) is thought to be related to reproductive disorders, especially in males. Growing evidence suggests that various EDCs may result in an impaired telomere structure and function, which is associated with male infertility. However, the adverse effect of DEHP on telomeres in male reproductive cells has rarely been studied, and the related mechanisms remain unclear. In this study, we tested the effects of mono-(2-ethylhexyl) phthalate (MEHP), the primary metabolite of DEHP, on telomere dysfunction in mouse spermatogonia-derived cells (GC-1) and the potential role of TERT and c-Myc in MEHP-induced spermatogenic cell damage. Results showed that MEHP induced cell viability inhibition, G0/G1 phase cell cycle arrest, and apoptosis in GC-1 cells in a dose-dependent manner. Shortened telomeres, reduced telomerase activity, and decreased expression of TERT, c-Myc, and upstream transcription factors of c-Myc were also observed in the MEHP-treated cells. In conclusion, it can be concluded that TERT-mediated telomere dysfunction may contribute to MEHP-induced G0/G1 phase cell cycle arrest and apoptosis in GC-1 cells through the impairment of c-Myc and its upstream transcription factors.

Senolytics reduce endothelial cell DNA damage and telomere dysfunction in old age

Aging results in an accumulation of cellular damage that activates tumor suppressor pathways leading to permanent cell cycle arrest known as cellular senescence. Damage to DNA is a robust inducer of cellular senescence. Furthermore, repeat DNA sequences at the ends of chromosomes known as telomeres are particularly susceptible to damage that leads to senescence. Senescent cells adopt a pro-oxidative, pro-inflammatory phenotype that often adversely impacts the local tissue milieu. Senolytics are drugs that specifically induce cell death in senescent cells. Senolytic drugs have been shown to delay or reduce a multitude of age-related diseases in pre-clinical studies and are currently under investigation for use in clinical trials in humans. Many senolytic drugs were originally discovered based on their ability to induce cell death in senescent endothelial cells in cell culture. However, a key unanswered question is whether this phenomenon occurs in vivo. This is critical to understand because endothelial cell senescence contributes to both cardiovascular and metabolic diseases. In the present study, we tested the hypothesis that chronic administration of a senolytic cocktail will reduce the burden of endothelial cell senescence, as well as other molecular hallmarks of aging, including DNA damage and telomere dysfunction. To test this hypothesis, we treated 21-month-old mice (N = 10 / group) with the senolytic drug cocktail dasatinib (D, 5 mg/kg body mass) and quercetin (Q, 50mg/kg body mass) on three consecutive days every two weeks for three months via oral gavage. Control mice were treated with vehicle control (10% polyethylene glycol 4000 solution). At 24 months of age, carotid artery endothelial cell mRNA was isolated and expression of the cyclin-dependent kinase inhibitor that enforces senescence known as p21 was reduced in D+Q treated compared to vehicle-treated mice (p < 0.05). Additionally, lungs from 10 mice per group were collected and pooled, CD31+ lung endothelial cells were isolated and cultured briefly, and ~267 cells per group were examined. Immunofluorescence for the DNA damage marker 53BP1 demonstrated that treatment with D+Q reduced the percentage of endothelial cells with DNA damage (p < 0.05). We also performed immunofluorescence-fluorescent in situ hybridization to detect the abundance of 53BP1 foci colocalized to telomeres, a measure of telomere-specific damage known as telomere dysfunction-induced foci (TIF). Treatment with D+Q reduced the percentage of endothelial cells containing TIF (p < 0.05). Taken together, these data demonstrate that treating aged mice with D+Q reduces endothelial cell senescence likely in part by clearing cells that have accumulated DNA damage and dysfunctional telomeres. National Institutes of Health Awards R01 AG048366 (LAL), R01 AG060395 (AJD), 5K08AG070281 (ET), 1F31AG076312 (SIB). Veteran's Affairs Merit Review Award I01 BX004492 (LAL) from the United States (U.S.) Department of Veterans Affairs Biomedical Laboratory Research and Development Service. The contents do not represent the views of the U.S. Department of Veterans Affairs, the National Institutes of Health, or the United States Government. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Buildup from birth onward of short telomeres in human hematopoietic cells.

Telomere length (TL) limits somatic cell replication. However, the shortest among the telomeres in each nucleus, not mean TL, is thought to induce replicative senescence. Researchers have relied on Southern blotting (SB), and techniques calibrated by SB, for precise measurements of TL in epidemiological studies. However, SB provides little information on the shortest telomeres among the 92 telomeres in the nucleus of human somatic cells. Therefore, little is known about the accumulation of short telomeres with age, or whether it limits the human lifespan. To fill this knowledge void, we used the Telomere-Shortest-Length-Assay (TeSLA), a method that tallies and measures single telomeres of all chromosomes. We charted the age-dependent buildup of short telomeres (<3 kb) in human hematopoietic cells from 334 individuals (birth-89 years) from the general population, and 18 patients with dyskeratosis congenita-telomere biology disorders (DC/TBDs), whose hematopoietic cells have presumably reached or are close to their replicative limit. For comparison, we also measured TL with SB. We found that in hematopoietic cells, the buildup of short telomeres occurs in parallel with the shortening with age of mean TL. However, the proportion of short telomeres was lower in octogenarians from the general population than in patients with DC/TBDs. At any age, mean TL was longer and the proportion of short telomeres lower in females than in males. We conclude that though converging to the TL-mediated replicative limit, hematopoietic cell telomeres are unlikely to reach this limit during the lifespan of most contemporary humans.

Male Germ Cell Telomeres and Chemical Pollutants.

In recent decades, male infertility has been correlated with the shortening of sperm telomeres. Telomeres regulate the reproductive lifespan by mediating the synapsis and homologous recombination of chromosomes during gametogenesis. They are composed of thousands of hexanucleotide DNA repeats (TTAGGG) that are coupled to specialized shelterin complex proteins and non-coding RNAs. Telomerase activity in male germ cells ensures that the telomere length is maintained at maximum levels during spermatogenesis, despite telomere shortening due to DNA replication or other genotoxic factors such as environmental pollutants. An emerging body of evidence has associated an exposure to pollutants with male infertility. Although telomeric DNA may be one of the important targets of environmental pollutants, only a few authors have considered it as a conventional parameter for sperm function. The aim of this review is to provide comprehensive and up-to-date data on the research carried out so far on the structure/function of telomeres in spermatogenesis and the influence of environmental pollutants on their functionality. The link between pollutant-induced oxidative stress and telomere length in germ cells is discussed.

Abstract CT050: A phase 2, multi-center, open-label, dose-finding study evaluating telomere targeting agent THIO sequenced with cemiplimab in patients with advanced NSCLC

Abstract Background: The modified nucleoside 6-thio-2'-deoxyguanosine (THIO) is a first-in-class direct telomere-targeting agent that is preferentially incorporated in telomeres of telomerase-positive cells, leading to telomere uncapping and cancer cell death. Preclinical evidence indicates that THIO pretreatment sensitizes non-small cell lung cancer (NSCLC) cells to cemiplimab, a PD-1 inhibitor approved as 1L treatment for patients with locally advanced/metastatic NSCLC with ≥50% PD-L1 expression. The THIO-101 trial is designed to evaluate safety and efficacy of THIO followed by cemiplimab in patients with advanced NSCLC who have developed resistance or relapsed after prior immune checkpoint inhibitor (ICI) therapy. Trial Design: THIO-101 enrolls adult patients with stage 3/4 NSCLC, who have progressed or relapsed after treatment with an ICI alone or in combination with platinum-based therapy. Using a 3+3 design, the safety lead-in (Part A) is enrolling up to 6 patients in the first cohort to receive a total dose of THIO 360 mg IV (120 mg QD, D1-3) followed by a fixed dose of cemiplimab 350 mg on D5 Q3W. If ≥2 patients experience dose-limiting toxicities, a second cohort will receive a total dose of THIO 180 mg IV (60 mg QD, D1-3) followed by cemiplimab. In the dose- finding portion of the study (Part B), patients will be randomized 1:1:1 in a Simon 2-stage design (n=41 per arm) to receive THIO 360 mg [if cleared in Part A], 180 mg, or 60 mg followed by cemiplimab. Sequential THIO and cemiplimab treatment may be continued Q3W for up to 1 year, or until disease progression, unacceptable toxicity, or withdrawal of consent. The primary endpoints are safety, objective response rate, and disease control rate (CR, PR, and SD). Secondary endpoints include duration of response, progression-free survival, and overall survival; exploratory endpoints include PK/PD parameters (type I IFN, IL-6, CRP) and assessment of tumor telomerase status by IHC. Investigators will assess disease progression per RECIST v1.1 and/or iRECIST, with radiographic scans performed on D1 of cycles 3 and 5 and every 9-12 weeks thereafter. Adverse events are evaluated according to NCI CTCAE v5.0. The trial is enrolling patients at sites in Europe and Australia. The trial has completed enrollment in Part A without DLTs and opened enrollment in Part B. NCT05208944; EUDRA CT Number, 2021-005136-34 Citation Format: Mihail Obrocea, Brenton Seidl, Rohit Joshi, Melissa Moore, Vlad Vitoc, Bin Yao, Sergei Gryaznov. A phase 2, multi-center, open-label, dose-finding study evaluating telomere targeting agent THIO sequenced with cemiplimab in patients with advanced NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT050.

Influence of telomerase activity and initial distribution on human follicular aging: Moving from a discrete to a continuum model.

A discrete model is proposed for the temporal evolution of a population of cells sorted according to their telomeric length. This model assumes that, during cell division, the distribution of the genetic material to daughter cells is asymmetric, i.e. chromosomes of one daughter cell have the same telomere length as the mother, while in the other daughter cell telomeres are shorter. Telomerase activity and cell death are also taken into account. The continuous model is derived from the discrete model by introducing the generational age as a continuous variable in [0,h], being h the Hayflick limit, i.e. the number of times that a cell can divide before reaching the senescent state. A partial differential equation with boundary conditions is obtained. The solution to this equation depends on the initial telomere length distribution. The initial and boundary value problem is solved exactly when the initial distribution is of exponential type. For other types of initial distributions, a numerical solution is proposed. The model is applied to the human follicular growth from preantral to preovulatory follicle as a case study and the aging rate is studied as a function of telomerase activity, the initial distribution and the Hayflick limit. Young, middle and old cell-aged initial normal distributions are considered. In all cases, when telomerase activity decreases, the population ages and the smaller the h value, the higher the aging rate becomes. However, the influence of these two parameters is different depending on the initial distribution. In conclusion, the worst-case scenario corresponds to an aged initial telomere distribution.

Excision of Integrated Human Herpesvirus 6A Genomes Using CRISPR/Cas9 Technology.

Human herpesviruses 6A and 6B are betaherpesviruses that can integrate their genomes into the telomeres of latently infected cells. Integration can also occur in germ cells, resulting in individuals who harbor the integrated virus in every cell of their body and can pass it on to their offspring. This condition is termed inherited chromosomally integrated HHV-6 (iciHHV-6) and affects about 1% of the human population. The integrated HHV-6A/B genome can reactivate in iciHHV-6 patients and in rare cases can also cause severe diseases including encephalitis and graft-versus-host disease. Until now, it has remained impossible to prevent virus reactivation or remove the integrated virus genome. Therefore, we developed a system that allows the removal of HHV-6A from the host telomeres using the CRISPR/Cas9 system. We used specific guide RNAs (gRNAs) targeting the direct repeat region at the ends of the viral genome to remove the virus from latently infected cells generated in vitro and iciHHV-6A patient cells. Fluorescence-activated cell sorting (FACS), quantitative PCR (qPCR), and fluorescence in situ hybridization (FISH) analyses revealed that the virus genome was efficiently excised and lost in most cells. Efficient excision was achieved with both constitutive and transient expression of Cas9. In addition, reverse transcription-qPCR (RT-qPCR) revealed that the virus genome did not reactivate upon excision. Taken together, our data show that our CRISPR/Cas9 approach allows efficient removal of the integrated virus genome from host telomeres. IMPORTANCE Human herpesvirus 6 (HHV-6) infects almost all humans and integrates into the telomeres of latently infected cells to persist in the host for life. In addition, HHV-6 can also integrate into the telomeres of germ cells, which results in about 80 million individuals worldwide who carry the virus in every cell of their body and can pass it on to their offspring. In this study, we develop the first system that allows excision of the integrated HHV-6 genome from host telomeres using CRISPR/Cas9 technology. Our data revealed that the integrated HHV-6 genome can be efficiently removed from the telomeres of latently infected cells and cells of patients harboring the virus in their germ line. Virus removal could be achieved with both stable and transient Cas9 expression, without inducing viral reactivation.

Longitudinal telomere dynamics within natural lifespans of a wild bird

Telomeres, the nucleotide sequences that protect the ends of eukaryotic chromosomes, shorten with each cell division and telomere loss may be influenced by environmental factors. Telomere length (TL) decreases with age in several species, but little is known about the sources of genetic and environmental variation in the change in TL (∆TL) in wild animals. In this study, we tracked changes in TL throughout the natural lifespan (from a few months to almost 9 years) of free-living house sparrows (Passerdomesticus) in two different island populations. TL was measured in nestlings and subsequently up to four times during their lifetime. TL generally decreased with age (senescence), but we also observed instances of telomere lengthening within individuals. We found some evidence for selective disappearance of individuals with shorter telomeres through life. Early-life TL positively predicted later-life TL, but the within-individual repeatability in TL was low (9.2%). Using genetic pedigrees, we found a moderate heritability of ∆TL (h2 = 0.21), which was higher than the heritabilities of early-life TL (h2 = 0.14) and later-life TL measurements (h2 = 0.15). Cohort effects explained considerable proportions of variation in early-life TL (60%), later-life TL (53%), and ∆TL (37%), which suggests persistent impacts of the early-life environment on lifelong telomere dynamics. Individual changes in TL were independent of early-life TL. Finally, there was weak evidence for population differences in ∆TL that may be linked to ecological differences in habitat types. Combined, our results show that individual telomere biology is highly dynamic and influenced by both genetic and environmental variation in natural conditions.

Sirtuins and redox signaling interplay in neurogenesis, neurodegenerative diseases, and neural cell reprogramming.

Since the discovery of Neural Stem Cells (NSCs) there are still mechanism to be clarified, such as the role of mitochondrial metabolism in the regulation of endogenous adult neurogenesis and its implication in neurodegeneration. Although stem cells require glycolysis to maintain their stemness, they can perform oxidative phosphorylation and it is becoming more and more evident that mitochondria are central players, not only for ATP production but also for neuronal differentiation's steps regulation, through their ability to handle cellular redox state, intracellular signaling, epigenetic state of the cell, as well as the gut microbiota-brain axis, upon dietary influences. In this scenario, the 8-oxoguanine DNA glycosylase (OGG1) repair system would link mitochondrial DNA integrity to the modulation of neural differentiation. On the other side, there is an increasing interest in NSCs generation, from induced pluripotent stem cells, as a clinical model for neurodegenerative diseases (NDs), although this methodology still presents several drawbacks, mainly related to the reprogramming process. Indeed, high levels of reactive oxygen species (ROS), associated with telomere shortening, genomic instability, and defective mitochondrial dynamics, lead to pluripotency limitation and reprogramming efficiency's reduction. Moreover, while a physiological or moderate ROS increase serves as a signaling mechanism, to activate differentiation and suppress self-renewal, excessive oxidative stress is a common feature of NDs and aging. This ROS-dependent regulatory effect might be modulated by newly identified ROS suppressors, including the NAD+-dependent deacetylase enzymes family called Sirtuins (SIRTs). Recently, the importance of subcellular localization of NAD synthesis has been coupled to different roles for NAD in chromatin stability, DNA repair, circadian rhythms, and longevity. SIRTs have been described as involved in the control of both telomere's chromatin state and expression of nuclear gene involved in the regulation of mitochondrial gene expression, as well as in several NDs and aging. SIRTs are ubiquitously expressed in the mammalian brain, where they play important roles. In this review we summarize the current knowledge on how SIRTs-dependent modulation of mitochondrial metabolism could impact on neurogenesis and neurodegeneration, focusing mainly on ROS function and their role in SIRTs-mediated cell reprogramming and telomere protection.

The impact of moderate endurance exercise on cardiac telomeres and cardiovascular remodeling in obese rats.

Hypercaloric nutrition and physical inactivity cause obesity, a potential driver of myocardial apoptosis and senescence that may accelerate cardiac aging. Although physical activity reduces mortality, its impact on myocardial aging is insufficiently understood. Here we investigated the effects of a hypercaloric high-fat diet (HFD) and regular exercise training on cardiac cells telomeres and histomorphometric indices of cardiac aging. Ninety-six 4-months old female Sprague-Dawley rats were fed for 10 months normal (ND) or a HFD diet. Half of the animals in each group performed 30 min treadmill-running sessions on 5 consecutive days per week. At study end, cardiomyocyte cross-sectional area (CSA), interstitial collagen content, vascular density, apoptotic and senescent cells, relative telomere length (RTL), and expression of telomerase-reverse transcriptase (Tert) as marker of telomere-related senescence and apoptosis were analyzed. Compared to ND, the HFD group developed obesity, higher CSA, lower capillary density and tended to have more apoptotic cardiomyocytes and interstitials cells. Myocardial RTL and the expression of Terf-1 and Terf-2 were comparable in sedentary HFD and ND animals. In the HFD group, regular moderate endurance exercise improved myocardial vascularization, but had no effect on CSA or apoptosis. Notably, the combination of exercise and HFD increased senescence when compared to sedentary ND or HFD, and reduced RTL when compared to exercise ND animals. Exercising HFD animals also showed a trend toward higher Tert expression compared to all other groups. In addition, exercise reduced Terf-1 expression regardless of diet. HFD-induced obesity showed no effects on myocardial telomeres and induced only mild morphologic alterations. Summarized, long-term moderate endurance exercise partially reverses HFD-induced effects but may even trigger cardiac remodeling in the context of obesity.

Translating Single Cell Secrets to Cancer Evolution Accelerates Personalized Therapy

Translating Single Cell Secrets to Cancer Evolution Accelerates Personalized Therapy

(-)-Epigallocatechin-3-Gallate Protects Human Skin Fibroblasts from Ultraviolet a Induced Photoaging.

Ultraviolet (UV) is a common stressor of skin and repeated UVA radiation contributes to photoaging. (-)-Epigallocatechin-3-Gallate (EGCG), as the major polyphenol that is found in green tea, and catechins and have shown considerable antioxidant capacity. Our study aims to explore the effects of EGCG on UVA-induced skin photoaging process and associated mechanisms. In this study, human skin fibroblasts (HSFs) were treated with UVA and EGCG, and subsequent changes in cell morphology, telomeres, antioxidant capacity, cell cycle, and related genes were evaluated to examine the role and mechanisms of EGCG in delaying skin photoaging. HSF exposed to UVA underwent an increase in aging-related biomarkers and telomere shortening. Also, UVA radiation inhibited the secretion of transforming growth factor-beta1 (TGF-β1), induced cell cycle arrest, down-regulated antioxidant enzymes, and promoted the accumulation of oxidative product malondialdehyde (MDA) to cause further damage to cells. Increased expression of matrix metalloproteinases (MMPs), tissue inhibitor of metalloproteinase-1 (TIMP-1), p66 at mRNA levels were also observed after UVA irradiation. EGCG treatment effectively inhibited above damage processes caused by UVA radiation in HSF. Our study indicated that the potential mechanism of EGCG retarding photoaging is closely related to its powerful antioxidant effects and the ability to regulate the expression of related genes, and the usage of EGCG will be a potential strategy in preventing skin photoaging induced by UVA radiation.

The Ratio of Biological Health Score to Immune Cell Telomere Length: A Reliable Index Indicating the Association Between the Severity of Injury and Senescence in Mustard-chemical Veterans

Background: Sulfur mustard (SM), a chemical weapon used in the Iraq-Iran war from 1983-1988, has multiple chronic complications. This study aimed to evaluate one of the long-act effects of SM, i.e. the senescence according to the severity of injury in veterans via the estimation of biological health score (BHS) and relative telomere length (TL) of immune cells. Materials and Methods: SM-chemical veterans were categorized into three groups according to the percentage of chemical injury (5-20%, 25-45%, and 50-70%). Healthy volunteers also participated as a control group. Eighteen biomarkers from different physiological systems (inflammatory/immune, endocrine, cardiovascular, and metabolic), and organs (liver and kidney) were used to estimate BHS. The TL of immune cells was also measured for each participant by monochrome multiplex real-time PCR. Results: There were significant correlations between age-adjusted TL (negative), BHS, and BHS/TL ratio (positive) and the percentage of injury. The TL was significantly decreased in all veterans with different injuries compared to healthy participants while it did not change in veterans with the injury percentages of 25-45% and 50-70%. The BHS in three groups of veterans was significantly higher than in healthy individuals. The BHS/TL ratio was significantly changed between all groups and increased with the progress of injury. Conclusion: The BHS and TL may not individually be accurate indices for the determination of senescence and biological aging while the ratio of these two parameters improves this defect and could be a more reliable index indicating biological aging in chemical veterans with different percentages of injury.

Association of longer telomere length in cancer cells and cancer-associated fibroblasts withworse prognosis.

Telomere dysfunction has been reported to be directly involved in carcinogenesis owing to chromosomal instability and immortalization; however, the clinicopathological significance of telomeres remains controversial. We have shown that telomere shortening occurs in normal-appearing duct cells at initiation and then continues during the progression of pancreatic cancer. In this study, we determined the clinicopathological and prognostic value of telomere length (TL) in cancer progression. TL in both cancer cells and cancer-associated fibroblasts (CAFs) was analyzed by high-throughput quantitative fluorescence in situ hybridization using a previously reported cohort comprising 1434 cases of adenocarcinoma (ADC), squamous cell carcinoma (SCC), adenosquamous carcinoma, hepatocellular carcinoma, and renal cell carcinoma (RCC), which are known cancers with a statistically significantly low incidence of alternative lengthening of telomeres. Cases were divided into 2 groups as follows: longer and shorter telomeres, according to the median TL of cancer cells and CAFs. The statistical significance of TL in cancer cells and CAFs on clinicopathological characteristics and prognosis was analyzed. There was a close association between TL in cancer cells and CAFs. Longer telomeres in cancer cells and CAFs were associated with aggressive features such as advanced stage, high mitosis score and nuclear score, poorly differentiated cancer, and desmoplastic stroma in ADC. Furthermore, a longer TL was an independent prognostic factor for ADC, SCC, and RCC. Longer telomeres are associated with worse prognosis in ADC, SCC, and RCC. Thus, TL is a novel biomarker for the diagnosis of aggressive cancers with poor prognoses.

Telomerase and Anticancer Treatment

Current chemotherapy uses compounds of organometallic nature that act with different mechanisms of action. Many pharmacological studies are directed toward the creation of compounds with more specific and selective activity toward tumor targets, including telomerase. The design and synthesis of such compounds with specific antitelomerase activity must consider the mechanism of action of the enzyme and its structure. The discovery of a close correlation between telomerase activation, cell immortalization and oncogenesis has suggested that telomerase inhibitors could be potent therapeutic agents, capable of selectively killing cancer cells. Inhibition of telomerase is expected to lead toward shortening of telomeres to a critical length, such that replicative senescence and cell death due to irreparable chromosomal damage can result. It has been observed that cancer cells generally have shorter telomeres than the normal replicative cell population, probably because the malignant cells have undergone more divisions. Therefore, the inhibition telomeres of cancer cells after a few cycles of cell division, without the normal cells suffering harmful consequences during therapy. Telomerase is certainly an interesting target on which to continue to study molecules that inhibit its function to obtain a specificity of therapeutic intervention and a reduction of the nonspecific cytotoxicity of chemotherapy.