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The epigenetic clock

Contributed by paustian on Oct 02, 2016 - 04:32 PM

Have you ever noticed that some people seem to age faster than other people? I am not talking about individuals with Progeria. Instead, I mean just in your regular group of friends, how some seem to age faster than others. Many will chalk this up to poor nutrition, too much drinking, bad habits like smoking, and a lack of exercise. However, even if you factor all those things out, it seems like some people just age faster than others.

Enter professor Steven Horvath of UCLA. Dr. Horvath works on aging and has been pursuing a method of predicting the age of someone based upon markers in their cells. Having this tool will aid geriatric researchers in their efforts to slow cellular aging. (You have to be able to measure aging before you can find things to slow or stop it.) He has found a few methods by measuring saliva and hormone levels, but his most interesting, in my opinion. is the epigenetic clock. This work takes advantage of the fact that as cells age the methylation pattern on the DNA (our chromosomes) changes. By looking at 121 studies and the over 8,000 samples collected by these studies, his team was able to identify 350 sites where methylation changes as we age. This methylation may cause changes to gene expression, and these changes can lead to deleterious effects.

The researchers then tested the feasibility of this clock by examining the biological age of various samples and then comparing them to the chronological age of the source. It worked! In most cases, they were able to pinpoint the age of the person from which the sample came, but there were some interesting outliers. If you happened to have a predicted biological age was > 5 years higher than your chronological age, you had a 21% higher chance of death. It will be interesting in further research to determine what is different about these individuals, but the research, found in Genome Biology clearly shows the usefulness of the epigenetic clock

One other finding from this work I find particularly interesting. The epigenetic clock of induced pluripotent stem cells (adult stem cells that have been reverted to their embryonic state) is reset to 0. This reveals the intriguing idea that it may be possible to slow, stop, or reverse the cellular aging process. What effect would that have on the organism? Will we be able to extend life? How far? Interesting possibilities.