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Dyskeratosis Congenita
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
Telomeres are specialized structures at the end of chromosomes, consisting of nucleic acid and protein components that maintain the integrity of chromosome ends, protecting the natural ends of chromosomes from loss of DNA, abnormal fusion to other chromosomes, and from activation of DNA damage pathway response which may otherwise occur at free ends of DNA created by strand breaks. Telomeres shorten (attrition) with each cell division as a result of loss of 50–100 bp of the telomeric DNA due to incomplete replication of 3′ ends by conventional DNA polymerases, which is called the end-replication problem. When telomeres reach a critically short threshold, the cell can no longer divide properly and undergo apoptosis or senescence. In somatic cells, telomere loss is a normal consequence of aging. For example, average lymphocyte telomere length declines from approximately 11 kb at birth to only approximately 4 kb in elderly population. Hence, telomere is regarded as “biological clock” within a cell that determines the number of possible cell divisions [7,8].
Conclusion
Published in Karin Volkwein-Caplan, Jasmin Tahmaseb McConatha, Ageing, Physical Activity and Health, 2018
Karin Volkwein-Caplan, Jasmin Tahmaseb McConatha
In the most industrialized societies, the maximal human life expectancy has increased from 49 in 1900 to almost 80 in 2017. As the chapters in this book suggest, lifestyle and the environment play important roles in the aging process. They affect our genes as well. In recent years, scientists have linked the shortening of telomeres to cardio-vascular disease, obesity, diabetes, and many forms of cancer and osteoporosis (Csatari, 2017). Gene researchers believe that lengthening telomeres might prevent these chronic diseases (Masood, 2011; Tzanetakou et al., 2014). Taking steps to optimize healthy aging can help protect telomeres. Indeed, the chapters in the book demonstrate that being physically fit, happy, and socially engaged can protect telomeres and, in turn, extend one’s longevity.
The aging body
Published in Jennifer R. Sasser, Harry R. Moody, Gerontology, 2018
Jennifer R. Sasser, Harry R. Moody
Is there a distinctive “clock” to measure the rate of cellular senescence? It appears that there is. In both humans and other animals, cellular senescence can be recognized by tiny structures in the cell known as telomeres (see Figure 2.2). Telomeres are the “caps” on the tips of chromosomes. In each cycle of cell division, telomeres get shorter. Reduction in the length of telomeres has been shown to be linked to biological aging. A specific enzyme in the nucleus of the cell, telomerase, works constantly to rebuild the tips of chromosomes. Telomeres have a paradoxical relationship with cancer. Telomere shortening may prevent cancer in human cells by limiting the number of cell divisions. At the same time, shortened telomeres could impair immune function and increase vulnerability to cancer. For this reason, it seems unlikely that simply introducing telomerase or interfering with telomeres alone will in itself slow the process of aging.
Maternal neglect results in reduced telomerase activity and increased oxidative load in rats
Published in Stress, 2021
Devrim Sarıbal, Aslı Kireçtepe Aydın, Mahmut Alp Kılıç, Faariah Shakil, Mustafa Balkaya
Telomere shortening is considered a hallmark of aging, as telomere length reflects mitotic potential and age is a primary predictor of telomere length. However, numerous environmental factors such as poverty, smoking, alcohol use, obesity, and a sedentary lifestyle have been shown to affect telomere length (Barrett et al., 2015). Social factors such as marital status, social support, social conflicts, isolation have been associated with telomere length as well. Significant environmental factors that accelerate aging are adverse social conditions and chronic psychological stress. Accordingly, a growing body of evidence from human studies links stress exposure to reduced telomere length. Stressful life events, particularly the ones during early childhood, are associated with telomere attrition and predict greater telomere shortening with age (Oliveira et al., 2016; Rentscher et al., 2020). Similarly, exposure to violence or being a caregiver for chronically ill patients leads to reductions in telomere length (Oliveira et al., 2016). Nevertheless, the effects of stress on telomerase activity is grossly understudied (de Punder et al., 2019). Rodent studies on the topic are very limited and report conflicting results. Therefore, establishing animal models that mimic the phenotype observed in humans is crucial for studying the effects of stress on telomere shortening and associated diseases.
Association between nutrient intake and telomere length in Japanese female university students
Published in Biomarkers, 2021
Yuki Mizuno, Shoko Konishi, Chiho Goto, Jun Yoshinaga, Mikie Hidaka, Hideki Imai
The telomere length of DNA in a cell is considered a biomarker of cellular aging. Telomeres comprise highly repetitive nucleotide sequences (5′- (TTAGGG)n -3′ in humans) and telomere-binding proteins and are located at the ends of each chromosome. Telomeres act as caps for chromosomes, prevent their end-to-end fusion, and preserve their integrity. Thus, they contribute towards genomic stability (Kurenova and Mason 1997). Most somatic cells lack activated telomerase, i.e. the specific enzyme required to lengthen the telomere (López-Otín et al. 2013). Telomere length gets progressively shorter with each cell division because of the end-replication problem (Blackburn 2005). Eventually at a certain point, telomere length is critically shortened, and the cell enters senescence (López-Otín et al. 2013).
Telomere length is not altered in girls with idiopathic central precocious puberty treated with a GnRH analog – leuprolide acetate
Published in Gynecological Endocrinology, 2020
Cristiana Libardi Miranda Furtado, Renata Iannetta, Rui Alberto Ferriani, Ana Carolina J. S. Rosa E Silva, Carlos Eduardo Martinelli, Rodrigo Tocantins Calado, Rosana Maria dos Reis
Telomeres are the most recognized biomarkers of aging and age-related diseases. These specialized DNA–protein structures are found at the ends of chromosomes, which wrap around and protect the DNA from degradation, thereby, maintaining genomic stability [8,9]. Telomeres determine the proliferative life span of a cell, and they shorten with each mitotic division. Telomerase activity is responsible for maintaining telomeres and replicating the ends of the chromosomes [10]. Several factors affect telomerase activity and, therefore, the maintenance of telomeres. Steroid hormones, such as androgens and estrogens, seem to stimulate telomerase activity [11,12]. The shortening of telomeres can be accelerated by age [13], and environmental factors, such as obesity, metabolic disorders and psychological stress [14,15].