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Telomere Shortening - The Secret to Aging?

Can telomeres explain aging?


Updated May 30, 2014

Telomeres are bits of “junk DNA” at the end of chromosomes that protect your real DNA every time a cell divides. What happens is that, due to how cells divide, the very last bit of a chromosome can’t be copied 100% - a little bit gets cut off. It was thought that, as cell divide, the telomeres get shorter each time, until, they are gone. At that point, the “real DNA” cannot be copied anymore and the cell simply ages and no longer replicates.

Telomere Shortening and Aging

In population level studies, researchers have shown that older people have shorter telomeres. Eventually, the cells with shorter telomeres can no longer replicate and, taken over time and lots of cells, tissue damage and the dreaded “signs of aging” can show up. Most cells can replicate about 50 times before the telomeres are too short. Some believe that telomeres are the “secret to longevity” and there are circumstances in which the telomeres will not shorten. Cancer cells, for example, don’t die (which is the main problem) because they switch on an enzyme called telomerase, which adds to the telomeres when cells divide. Some cells in your body need to do this (stem cells and sperm cells, for example) because they need to replicate more than 50 times in your lifetime.

Does It Happen to Everyone?

No — and that’s a big surprise. Researchers in Sweden found out that some people’s telomeres do not necessarily get shorter over time. In fact, they found that some people’s telomeres even get longer. This variation at the individual level was hidden by prior studies that averaged results over large population.

What Does Non-Shortening Telomeres Mean?

In the study, 959 individuals donated blood twice, 9 to 11 years apart. On average, the second samples had shorter telomeres than the first. However, around 33% of the people had either a stable or increasing telomere length over a period of around 10 years. What does this mean? Nobody knows. It could be that those people have an amazing cellular anti-aging mechanism or it could be that they have an early sign of cancer (researchers tried to rule this out) or it could be fairly meaningless. What we do know for sure is that aging is a lot more complicated than simply looking at the shortening of telomeres.

Read More: Theories of Aging

Source: Nordfjäll K, Svenson U, Norrback K-F, Adolfsson R, Lenner P, Roos G. The individual blood cell telomere attrition rate is telomere length dependent. PLoS Genetics, February 13, 2009 DOI: 10.1371/journal.pgen.1000375[/sun]

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