Author: Ella Chen
Editors: Yueshan Yu, Hanni Yang, and Junyu Zheng
Artist: Carys Chan
We all age as time passes, but have you ever wondered what affects aging? Why do some people look younger than their age while others look older? Scientists have conducted extensive research on the factors that affect aging and have discovered one key structure: telomeres. A telomere is a region of repetitive DNA sequences located at the end of a chromosome, protecting it from damage. Telomeres play a critical role in cell division and, by association, in the aging processes.
Telomeres, located at the end of chromosomes, consist of around 3,000 repeated nucleotide sequences. In humans, the repeated sequence is TTAGGG, which helps maintain chromosome stability. Telomeres ensure proper chromosome replication during the S phase of the cell cycle. Each time a cell replicates its DNA, the chromosomes are shortened by 25 to 200 nucleotide bases. Since telomeres protect chromosomes, no important DNA is lost during replication, allowing the cell to function as usual. However, with each division, telomeres lose a small portion of their nucleotide bases. This gradual shortening leads to the telomere being too short, preventing the chromosome from replicating. This is where its effect on aging comes into play—when the telomeres reach the point at which the cell can no longer divide efficiently, the cell becomes senescent, entering a state in which cells permanently stop dividing. During this stage of cellular senescence, the cells are not dead but instead exist in a stage of inactivity.
As we age, the number of senescent cells in our body increases due to repeated cell divisions and the significant telomere shortening. An increase in senescent cells can damage healthy cells and impact crucial functions such as the production of proteins like collagen and elastin, which give skin its structure and firmness. Without these proteins, the skin begins to sag and develop wrinkles—visible traits of aging. Furthermore, senescent cells can release an inflammatory senescence-associated secretory phenotype (SASP), which can cause chronic inflammation in cells and potentially promote tumor progression. The effects of SASP compromise a person’s ability to withstand illness, recover from injuries, and maintain cognitive functions. These symptoms are also linked to age-related diseases, including arthritis, cardiovascular disease, cancer, and dementia. Thus, the shortening of telomeres plays a key role in the aging process by triggering the accumulation of cellular senescence and a decline in cellular functions.
Research on telomeres and aging has led scientists to study ways to reduce the effects of shortened telomeres, opening up opportunities to promote healthier aging and mitigate the risk of developing age-related diseases later in life. One such example of a study is one conducted by Kirkland and colleagues in 2019. They administered a “cocktail” of two drugs—dasatinib (D), commonly used in leukemia chemotherapy, and quercetin (Q), which has natural anti-inflammatory properties--to individuals with idiopathic pulmonary fibrosis and others with diabetic kidney disease. They found that the combination of D and Q could clear senescent cells in both groups of research participants. The results of this study provide promising evidence that there are ways to counteract the effects of shortened telomeres and increased amounts of senescent cells.
However, addressing the effects of shortened telomeres is not limited to treatment after one is already affected by them. There are ways to maintain telomere length so they do not shorten excessively over time due to cell division. These methods mainly focus on lifestyle factors, such as diet and exercise. In several studies, the Mediterranean diet, rich in legumes (beans, peas, lentils), whole grains, fresh fruit, and vegetables, has proven to be positively associated with telomere length because of its antioxidant and anti-inflammatory properties. In one study, Harvard researchers surveyed more than 4,500 people about their diets and measured their telomeres. They found that greater adherence to the Mediterranean diet was linked to longer telomeres. In addition to diet, regular physical activity—whether going to the gym or simply taking a walk daily—helps preserve telomere length. Moreover, getting enough sleep, avoiding stress, and not smoking are also factors that promote healthy aging. These preventive measures can help maintain telomere length and prevent age-related diseases from arising in future years.
Though much research remains to be done on treatments like those conducted by Kirkland and colleagues, these studies show that it is not impossible to address conditions associated with aging. As research continues to advance and build upon existing studies, more insights into the aging process and how to combat its effects are revealed, creating more possibilities for healthier aging and improved quality of life.
Citations:
Lang, Katharine. “Are Telomeres Really the Key to Living Longer, Youthful Lives?”
National Institute on Aging. “Does Cellular Senescence Hold Secrets for Healthier Aging?”
National Institute on Aging, 13 July 2021, www.nia.nih.gov/news/does-cellular-
Rumiana Tenchov, et al. “Aging Hallmarks and Progression and Age-Related Diseases: A
Landscape View of Research Advancement.” ACS Chemical Neuroscience, vol. 15, no. 1,
American Chemical Society, Dec. 2023, https://doi.org/10.1021/acschemneuro.3c00531.
Shammas, Masood A. “Telomeres, Lifestyle, Cancer, and Aging.” Current Opinion in Clinical
Nutrition and Metabolic Care, vol. 14, no. 1, Jan. 2011, pp. 28–34,
“What Is a Telomere?” Www.yourgenome.org, www.yourgenome.org/theme/what-is-a-
Comments