What Is the Connection between Telomerase and Aging?

Telomerase is an enzyme produced by the body that slows the aging process at the molecular level by rebuilding the bits of DNA at the ends of chromosomes, called telomeres. During every cell division telomeres protect and aid the chromosome, which cannot divide all the way to its end. Telomeres also shorten slightly every time a cell divides while telomerase activity lengthens and rebuilds the telomere. Without telomerase, a cell can only divide a finite number of times before it “ages” and dies due to the shortening of its telomeres. The discovery of this process has fueled hopes that research into telomerase and aging might yield ways to delay or reverse the human aging process and its associated diseases and disorders.

In 2009, the Nobel Prize in Medicine was awarded to Carol Greider, Jack Szostak and Elizabeth Blackburn for their research that led to the discovery of telomerase in 1984. A study on mice focused on the connection between telomerase and aging. Mice that did not produce telomerase aged twice as fast as mice that had normal levels. When their telomerase was activated, all signs of aging reversed, with the brain and organs regenerating and functioning normally.

Results of this research explained one of the reasons people age. The link between telomerase and aging was strengthened when it was found that people who are born with premature aging disorders have short telomeres. A mutation of a telomerase subunit gene has been associated with various diseases and disorders, like aplastic anemia and other bone marrow diseases. Other studies have found that cells taken from people in their twenties divide more times before dying than cells from the elderly. Still other studies have failed to back this up.

Aging is a complex process governed by the interaction of a multitude of mechanisms. Many researchers argue that it is too early to apply what is known about telomerase and aging to humans since most of the research has been performed only on mice. Another potential problem is the role of telomerase in cancer.

Cancerous cells tend to have shorter telomeres and higher levels of telomerase that increase their growth. The introduction of telomerase antiaging therapy could be disastrous if a person has undetected cancers. Telomerase is one reason why cancerous cells grow out of control, in effect, becoming immortal. Some researchers suggest that people have limited amounts of telomerase to protect against cancer. Increasing levels could not only decrease the rate of aging, but stimulate cancer growth.

The link between telomerase and aging appears to be more complex than originally thought. While telomerase has a definite relationship to the rate at which cells and the whole organism ages, it is not the only factor at work. Scientists still cannot tell by telomere length how old a host might be because of the many processes involved in aging.