Pluripotent stem cells (PSCs) have the potential to produce any types of cells from all three basic germ layers and the capacity to self-renew and proliferate indefinitely in vitro. The two main types of PSCs, embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), share common features such as colony morphology, high expression of Oct4 and Nanog, and strong alkaline phosphatase activity. In recent years, increasing evidences suggest that telomere length represents another important internal factor in maintaining stem cell pluripotency. Telomere length homeostasis and its structural integrity help to protect chromosome ends from recombination, end fusion, and DNA damage responses, ensuring the divisional ability of mammalian cells. PSCs generally exhibit high telomerase activity to maintain their extremely long and stable telomeres, and emerging data indicate the alternative lengthening of telomeres (ALT) pathway may play an important role in telomere functions too. Such characteristics are likely key to their abilities to differentiate into diverse cell types in vivo. In this review, we will focus on the function and regulation of telomeres in ESCs and iPSCs, thereby shedding light on the importance of telomere length to pluripotency and the mechanisms that regulate telomeres in PSCs.
Animals ; Humans ; Models, Biological ; Pluripotent Stem Cells ; metabolism ; Telomerase ; metabolism ; Telomere ; metabolism ; Telomere Homeostasis

Potential maximum life span of humans is estimated around 115-120 years by Cutler. His estimate agrees with an earlier observation by Buffon who claimed that animals tended to live six times the period needed to complete their growth. As humans reach their skeletal maturity at approximately 20 years. Life span has not changed throughout recorded history. Life expectany, the actual average survival for certain given population has increased thanks to social, economic and medical advances. There are two basic levels of biological explanations on aging: macrobiological and microbiological. Macrobiological explanation includes homeostasis, immune system, endocrine, lifestyle, nutrition and environment. Microbiological explanation includes cellular clock theory, free radical theory and metabolic theory with nutrition and antioxidants. Recent advances of genetics opened new era on telomere and telemorase. Gene therapy is applied mainly at the laboratory or limited as local use under investigation. Although the results are encouraging at the laboratory, application for clinical purpose will need tremendous thorough trial and errors.
Aging ; Animals ; Antioxidants ; Genetic Therapy ; Genetics ; Homeostasis ; Humans ; Immune System ; Life Style ; Telomere

To investigate the effect of low power helium neon laser (He-Ne laser) on the telomere length of human fetal lung diploid fibroblast (2BS) cell, we used the laser (gamma = 632. 8 nm, P = 2 mW) to treat the young 2BS cells. Cell growth and proliferation was observed through MTT method after treating with low power laser. The relative telomere length of 2BS cells was detected by fluorescence real-time quantitative PCR (q-PCR). The results showed that the cells of the treated groups grew better than the untreated groups. The telomere DNA length of the old 2BS cells, treated by low power He-Ne laser when they were young, was longer than that of untreated group. The results of the present study indicated that the low power He-Ne laser might decrease shortening rate of telomere and delay the aging of cells. Therefore, this study provides the experimental basis for us to further investigate the effect of low power laser on cell aging at the gene level.
Cell Line ; Cellular Senescence ; radiation effects ; Fetus ; Fibroblasts ; cytology ; Humans ; Lasers ; Lung ; cytology ; Telomere Homeostasis ; radiation effects

Macroautophagy/autophagy is a conserved degradation system that engulfs intracytoplasmic contents, including aggregated proteins and organelles, which is crucial for cellular homeostasis. During aging, cellular factors suggested as the cause of aging have been reported to be associated with progressively compromised autophagy. Dysfunctional autophagy may contribute to age-related diseases, such as neurodegenerative disease, cancer, and metabolic syndrome, in the elderly. Therefore, restoration of impaired autophagy to normal may help to prevent age-related disease and extend lifespan and longevity. Therefore, this review aims to provide an overview of the mechanisms of autophagy underlying cellular aging and the consequent disease. Understanding the mechanisms of autophagy may provide potential information to aid therapeutic interventions in age-related diseases.
Aged ; Aging ; Autophagy ; Cell Aging ; DNA Damage ; Homeostasis ; Humans ; Longevity ; Neurodegenerative Diseases ; Organelles ; Oxidative Stress ; Telomere Shortening

Short telomeres are known as one of the risk factors for human cancers. The present study was conducted to evaluate the association between 6 polymorphisms, which were related with short telomere length in the Korean population, and lung cancer risk using 1,100 cases and 1,096 controls. Among the 6 polymorphisms, TERT rs2853669 was significantly associated with increased lung cancer risk under a recessive model (odds ratio [OR]=1.38, 95% confidence interval [CI]=1.05-1.81, P=0.02). The effect of rs2853669 on lung cancer risk was significant in younger individuals (OR=1.73, 95% CI=1.18-2.54, P=0.005) and adenocarcinoma (OR=1.50, 95% CI=1.07-2.07, P=0.02). Our results suggest that a common functional promoter polymorphism, TERT rs2853669, may influence both telomere length and lung cancer risk in the Korean population.
Adenocarcinoma/epidemiology/*genetics ; Case-Control Studies ; Female ; Gene Frequency/genetics ; Genetic Association Studies ; Genetic Predisposition to Disease ; Humans ; Lung Neoplasms/epidemiology/*genetics ; Male ; Middle Aged ; Polymorphism, Single Nucleotide/*genetics ; Promoter Regions, Genetic/*genetics ; Republic of Korea/epidemiology ; Telomerase/*genetics ; Telomere/physiology ; Telomere Homeostasis/*genetics

BACKGROUND/AIMS: A number of genome-wide and candidate gene association studies have identified polymorphisms associated with telomere length in Caucasian populations. This study was conducted to determine the impacts of 17 polymorphisms identified in Caucasians on telomere length in a Korean population. METHODS: Ninety-four healthy individuals were enrolled in this study. Relative telomere length of chromosomes from peripheral blood samples was measured using quantitative polymerase chain reaction. RESULTS: Two polymorphisms, rs10936599 of MYNN and rs412658 of ZNF676, were found to be associated w ith telomere length (under dominant model, p = 0.04; under recessive model, p = 0.001). Three polymorphisms, rs2853669, rs7705526, and rs2736108, at the TERT locus were also associated with telomere length (under recessive model, p = 0.01, p = 0.02, and p = 0.01, respectively). The genotypes of the five polymorphisms associated with short telomere length were considered bad genotypes; telomere length was significantly decreased with increasing number of bad genotypes (p= 1.7 x 10(-5)). CONCLUSIONS: We have identified polymorphisms associated with telomere length in a Korean population.
Adult ; Aged ; Asian Continental Ancestry Group/*genetics ; Case-Control Studies ; DNA-Binding Proteins/genetics ; Female ; Genome-Wide Association Study ; Genotype ; Humans ; Kruppel-Like Transcription Factors/genetics ; Male ; Middle Aged ; Phenotype ; *Polymorphism, Single Nucleotide ; Republic of Korea ; Telomerase/genetics ; Telomere/*genetics/metabolism ; *Telomere Homeostasis ; Zinc Fingers

Werner syndrome (WS) is a premature aging disorder that mainly affects tissues derived from mesoderm. We have recently developed a novel human WS model using WRN-deficient human mesenchymal stem cells (MSCs). This model recapitulates many phenotypic features of WS. Based on a screen of a number of chemicals, here we found that Vitamin C exerts most efficient rescue for many features in premature aging as shown in WRN-deficient MSCs, including cell growth arrest, increased reactive oxygen species levels, telomere attrition, excessive secretion of inflammatory factors, as well as disorganization of nuclear lamina and heterochromatin. Moreover, Vitamin C restores in vivo viability of MSCs in a mouse model. RNA sequencing analysis indicates that Vitamin C alters the expression of a series of genes involved in chromatin condensation, cell cycle regulation, DNA replication, and DNA damage repair pathways in WRN-deficient MSCs. Our results identify Vitamin C as a rejuvenating factor for WS MSCs, which holds the potential of being applied as a novel type of treatment of WS.
Animals ; Ascorbic Acid ; pharmacology ; Cell Cycle Checkpoints ; drug effects ; Cell Line ; Cellular Senescence ; drug effects ; DNA Damage ; DNA Repair ; drug effects ; DNA Replication ; drug effects ; Disease Models, Animal ; Heterochromatin ; metabolism ; pathology ; Humans ; Mesenchymal Stem Cells ; metabolism ; pathology ; Mice ; Nuclear Lamina ; metabolism ; pathology ; Reactive Oxygen Species ; metabolism ; Telomere Homeostasis ; drug effects ; Werner Syndrome ; drug therapy ; genetics ; metabolism

Human telomerase reverse transcriptase (hTERT) plays a central role in telomere lengthening for continuous cell proliferation, but it remains unclear how extracellular cues regulate telomerase lengthening of telomeres. Here we report that the cytokine bone morphogenetic protein-7 (BMP7) induces the hTERT gene repression in a BMPRII receptor- and Smad3-dependent manner in human breast cancer cells. Chonic exposure of human breast cancer cells to BMP7 results in short telomeres, cell senescence and apoptosis. Mutation of the BMPRII receptor, but not TGFbRII, ACTRIIA or ACTRIIB receptor, inhibits BMP7-induced repression of the hTERT gene promoter activity, leading to increased telomerase activity, lengthened telomeres and continued cell proliferation. Expression of hTERT prevents BMP7-induced breast cancer cell senescence and apoptosis. Thus, our data suggest that BMP7 induces breast cancer cell aging by a mechanism involving BMPRII receptor- and Smad3-mediated repression of the hTERT gene.
Actin-Related Protein 2 ; genetics ; metabolism ; Activin Receptors, Type II ; genetics ; metabolism ; Bone Morphogenetic Protein 7 ; genetics ; metabolism ; Bone Morphogenetic Protein Receptors, Type II ; genetics ; metabolism ; Breast Neoplasms ; genetics ; metabolism ; Cellular Senescence ; Female ; HeLa Cells ; Humans ; MCF-7 Cells ; Neoplasm Proteins ; genetics ; metabolism ; Protein-Serine-Threonine Kinases ; genetics ; metabolism ; Receptor, Transforming Growth Factor-beta Type II ; Receptors, Transforming Growth Factor beta ; genetics ; metabolism ; Smad3 Protein ; genetics ; metabolism ; Telomerase ; genetics ; metabolism ; Telomere Homeostasis