Although they seem like the most boring component of DNA, recent evidence shows that the tips of chromosomes could hold the secret to longer life.
Called telomeres, these bits of DNA don’t function in the cell in a manner we’re used to thinking about – they make no protein and are in no direct way involved with cell regulation, but their job is a pretty neat one. Every time a cell divides, the chromosomes must replicate. When this happens, some of the tips of the chromosomes are lost – about 50 to 200 units of that infamous genetic code. If this loss encroached on important genes, the effect on the cell - and us - could be dire, so having these expendable bits of DNA at the tips is a protective measure. Think of the plastic doohickeys on your shoelaces that prevent unraveling.
This constant loss of DNA puts a limit on how many times a cell can divide. Some estimates put this limit at about fifty in humans. After this, cells enter a state called “senescence” where they cannot divide. As a result, vital organs may begin to fail and the signs of aging commence. The effects of this are gigantic: running out of telomeres means the end of one’s life. The secret to long life might not be in your eating habits or physical activity but in your genes.
Last month, the Nobel Prize was awarded to a group of scientists at the Albert Einstein College of Medicine for finding an enzyme more prevalent in very old people that helps rebuild telomeres. Also, these people had very long telomeres to begin with. Those with this enzyme were spared age-related diseases such as diabetes and cardiovascular disease, which cause many deaths among elderly people.
The results of this research are huge. It may one day be possible to manufacture drugs that mimic the enzyme capacity found in these centenarians.
Ashkenazi Jews were used for the study because they are an endogamous population with a very high life expectancy. They observed 86 elderly men and women (mean age 97), 175 of their offspring, and 93 controls (offspring of parents who had lived a normal lifespan).
The enzyme of interest in this case was telomerase, an enzyme found in all humans. It is most active in the sex organs, since gametes (sperm and egg) must have very long telomeres in order to support a whole new person. It is also present in cells like bone marrow that must continuously divide, but it is not found in such senescent cells as neurons and cardiac tissue.