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What Are Telomeres and Why Are They Important?

What Are Telomeres and Why Are They Important?

The study of telomeres is a growing area of research, and one that I find really fascinating. I wanted to talk a little bit about telomeres, with the goal of laying the groundwork for some future posts about telomere research.

What are Telomeres?

telomereTelomeres are stretches of DNA at the end of our chromosomes and are a critical component of preserving the information in our genome. They are often compared to the plastic caps on shoelaces that keep the laces from fraying. Like those shoelace caps, telomeres act like caps that keep our chromosome ends from fraying and protect our genetic data from damage. They also prevent dangerous cells from replicating.

 

Why are Telomeres Important?

Every time a cell divides, the telomeres get shorter. If telomeres get too short or disappear, a cell’s chromosomes can fuse or rearrange, which can lead to genetic damage. Consequently, a cell generally will become inactive (senescent) if the telomeres become too short. The shortening of telomeres may predict the pace of aging, and animal studies suggest that limitations on cell division due to telomere shortening may be a primary factor determining lifespan limits.

Telomere shortening is associated with all aspects of the aging process, including cancer, and with a higher overall risk of death. Research suggests that telomere length is a reliable predictor of heart attack and stroke, independent of other factors. Conditions such as cardiovascular disease and cancer can also contribute to telomere shortening, regardless of age. Exceptionally short telomeres are found in most cancers, suggesting that cells with dysfunctional telomeres can lead to tumor growth.

Some cells in the body appear to be exempt from typical age-related telomere shortening. Germ cells (the cells that develop into sperm and eggs) and stem cells are some of the few types of cells containing telomerase, an enzyme that adds length to telomeres. This means that, despite dividing rapidly, these cells retain telomere length and do not show signs of aging.

Can We Slow Down Telomere Shortening?

As mentioned above, telomerase is an enzyme that elongates telomeres. There is research being conducted into using telomerase to lengthen telomeres in various cells throughout the body. However, telomerase is also found in cancer cells and is responsible for the ability of those cells to replicate and divide uncontrollably. Given the role of telomerase in tumor growth, it could be problematic to activate telomerase on a wide scale throughout the body. It will likely be a long time before telomerase can be used to slow down the effects of aging, if that is even possible. Fortunately, there seem to be some pretty straightforward strategies available to slow down telomere shortening without risking increased cancer growth.

The rate of telomere shortening can be heavily impacted by lifestyle choices. Some activities, such as smoking, can accelerate telomere shortening and thereby increase the rate at which cells age. Oxidative stress may have more of an impact on telomere shortening than does cell replication and may be a primary mechanism of age-related chronic disease. Chronic physiological stress is associated with negative impacts on physical health and with shorter telomeres. For this reason, stress management techniques may be an effective strategy for slowing telomere shortening.

By minimizing exposure to oxidative stress in our lives, there is the potential to slow down the breakdown of telomeres and consequently slow the effects of aging. Additionally, the effects of stress on telomere length may be buffered by regular physical activity. There is evidence that the positive effects of exercise are particularly apparent in older individuals. Diet also is likely to play a role in the rate of telomere shortening. Some early stage research is showing that some diet and exercise strategies not only slow down shortening, but might even promote telomere lengthening. Forthcoming posts will address more about the effects of specific dietary choices, exercise, and stress on telomere length.

What’s Next?

This was a very general overview of telomeres, and an exceptionally brief introduction to strategies available to slow telomere shortening. I’m excited to take a deeper dive into the topic and continue to explore further. It is a fascinating area of research with the potential for real-life applications that could contribute to improved health and quality of life.

 

Resources:

Beate et al. Telomere length and long-term endurance exercise: Does exercise training affect biological age? A pilot study. PLoS ONE. 2012; 7(12).

Fernandez, E. Lifestyle changes may lengthen telomeres, a measure of cell aging. UCSF. 2013.

Hiyama et al. Role of telomeres and telomerase in cancer. In: Hiyama K, editor. Telomeres and telomerase in cancer. Springer Science & Business Media, LLC 2009. 171-180.

Kaszubowska L. Telomere shortening and ageing of the immune system. Journal of Physiology and Pharmacology. 2008; 59(Suppl 9):169-186.

Puterman et al. The power of exercise: Buffering the effect of chronic stress on telomere length. PLoS ONE. 2010; 5(5).

Shammas, M. Telomeres, lifestyle, cancer, and aging. Curr Opin Clin Nutr Metab Care. 2011; 14(1), 28-34.

Sjögren, et al. Stand up for health: Avoiding sedentary behaviour might lengthen your telomeres: Secondary outcomes from a physical activity RCT in older people. British Journal of Sports Medicine. (2014); 48, 1407-1409.

Zglinicki, T. Oxidative stress shortens telomeres. TRENDS in Biochemical Sciences. 2002; 27(7), 339-344.



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