DNA research paving way for lifespan prediction

Research subjects that lived longest had the longest telomeres, or repetitive DNA sequences, at every measurement point.

By JUDY SIEGEL-ITZKOVICH
DNA strand double helix 311 (photo credit: Jerome Walker)
DNA strand double helix 311
(photo credit: Jerome Walker)
It may not be long before people will order a test to accurately predict how long they will live.
This could result from the discovery by a University of Glasgow team in Scotland showing that telomere length on the ends of DNA in their genes in early-life predicts lifespans.
A telomere, from the Greek words “end” and “part,” is a region of repetitive DNA sequences at the end of a chromosome and serves like a cap on shoelaces that prevents unravelling. The telomeres protect the end of the chromosomes in the genes from breaking down or melding with chromosomes near them. Chromosome ends naturally become shorter due to cell division.
As cells divide, enzymes that duplicate DNA cannot continue this process all the way to the end of the chromosomes. If cells divided without telomeres, they would lose the ends of their chromosomes, and the vital data they contain.
While the telomeres are “chewed up” during cell division, they are rebuilt by an enzyme called telomerase reverse transcriptase. This process occurs in most plants, animals and humans, alike.
Prof. Pat Monaghan headed the Glasgow team that on Tuesday published their findings in the American Proceedings of the National Academy of Sciences. The researchers were the first to measure telomere length in the young and then repeatedly during the rest of their natural lives. They found telomere length in early-life is strongly predictive of the individual’s subsequent lifespan.
The researchers measured telomere lengths in small samples of blood cells taken at various ages in a group of zebra finches – small black-, white- , orange-, and gray-striped and -spotted birds – whose lifespan varied from just 210 days to almost nine years. The best predictor of longevity was the telomere length at just 25 days.
Researcher Dr. Britt Heidinger said “while there was a lot of variation among individuals in telomere length, those birds that lived longest had the longest telomeres at every measurement point.” It is known that the variation in telomere length is partly inherited, but also varies due to variation in environmental factors such as exposure to stress.
Prof. Karen B. Avraham – a leading member of the department of human molecula genetics and biochemistry at Tel Aviv University’s Sackler Faculty of Medicine commented on the research.
“This discovery is a dramatic one, showing the strength of using model organisms to tell us about normal human health and disease. If a correlation between zebra finches and humans turns out to be relevant for telomere length and longevity, I predict it is a matter of time before we will all want to test the length of our telomeres,” she said. “The take-home message here should also be to reduce stress in our life from as early an age as possible – this may help us live longer.”
Monaghan also emphasized the importance of early-life conditions.
“Our study shows the great importance of processes [occurring] early in life. We now need to know more about how early life conditions can influence the pattern of telomere loss and the relative importance of inherited and environmental factors. This is the main focus of our current research,” she said.