DNA and the Secret to Aging
By Jessica Schneider, MD
Every day, every month, every year, time moves on and we get older. But what really drives aging? Some might say that our age is how many years we’ve been alive, but health-wise, one person’s 65 could be completely different than another’s – even with similar healthy lifestyles. So what causes the disconnect between chronological aging, and biological aging?
In the last 20 years or so, scientists believe they have identified one biomarker of the aging process: Telomeres.
Telomeres sit at the end of each and every one of your strands of DNA. These endcaps let enzymes that copy DNA know when the genetic sequence has ended and protect our DNA from degradation. But, as these enzymes copy DNA for cell multiplication they are unable to reach all the way to end of each telomere, meaning that slowly through the copying process our telomere’s shorten.
Why would the shortening of these little DNA endcaps make a difference?
Research suggests that it actually can make a huge difference. Telomere length is indicative of replicative senescence, or the point at which cells can no longer divide. Once telomeres are extinguished, the DNA they were attached to is no longer able to replicate – or even worse, can cause harmful mutations to take place. Obviously, this point does not happen to every cell in our body all at once, but as it starts happening in different areas or organs of the body, it can cause issues with healing, gene expression, and biological functions. Imagine cells on your skin are at the end of their normal cell lifespan and only half of them are able to replicate like usual. You may find that cuts take longer to heal, sores may appear, and wrinkles may form. Sound familiar?
That’s not all that telomeres affect when it comes to aging. Shortened telomeres have been associated with increased mortality, infertility, heart failure, immune issues, as well as decreased cognitive function in both human and mice models.
The good news? Our body has a handy enzyme called telomerase, which can actually add on to telomeres and in effect lengthen our body’s lifespan. Unfortunately, most multicellular beings, including us, are only born with a limited amount of telomerase which can run out at a certain point in our life. Thankfully, we do not have to sit idly by while our telomerase is used up and our telomeres get cut short. Telomerase isn’t the only way to lengthen our telomeres. Certain lifestyle factors have been found to help elongate telomeres, such as diet and exercise.
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Interestingly, scientists have found that tumors have extremely high levels of telomerase, which could explain how they are able to replicate so quickly to seemingly no end. Similarly, certain cell lines, such as those of Henrietta Lacks who’s cells have been one of the most important cell lines in medical research, have also been found to have high levels of telomerase, and almost seem to be immortal. As research continues, these findings may help us to develop new treatments and ways to increase telomerase in our bodies and lengthen both our telomeres and our life.