Out of 40,000 genes, researchers were able to isolate some involved in physical aging, taking a step closer towards unraveling the aging process.
Until now, known genes involved in physical aging were limited to those from individual model organisms like the C. elegans nematode, whose life expectancy was revealed to be influenced by about 1 percent of its genes. Researchers at the ETH Zurich and the JenAge consortium, however, have systematically gone through the genomes of the C. elegans nematode, mice and zebra fish and have identified genes associated with the aging process present in all three. These so-called orthologous genes are closely related to each other despite being found in different organisms and are present as well in humans.
By screening about 40,000 genes, the researchers were able to determine which ones were regulated in a similar fashion across the three organisms in every comparable aging stage, relying on the level of messenger RNA (mRNA) molecules found in the cells of the C. elegans nematode, mice and zebra fish. If there were a lot of mRNA copies for a certain gene, then the gene is active or upregulated. If mRNA copies are low, then the gene is experiencing low activity or is being downregulated.
To further filter down the genes, the researchers turned to statistical models to find which genes were being regulated in the same manner in the different organisms. They were able to narrow down 40,000 genes to just 30 that have significant influence over an organism's aging process.
For instance, blocking about a dozen of the genes extended the lifespan of the C. elegans nematode by a minimum of 5 percent. Block the bcat-1 gene and the mean lifespan of nematodes is increased by as much as 25 percent.
According to the researchers, the bcat-1 gene has this much of an effect because it is carrying a code for an enzyme responsible for degrading branched-chain amino acids. When these branched-chain amino acids were allowed to accumulate, they not only increased longevity in nematodes but ensured they remained healthy as well during the length of their extended lifespan.
The researchers have not explored the effects those 30 genes have on humans but a follow-up study is already being set up.
Published in the journal Nature Communications, the current study received funding support from the German Ministry for Education and Research's Jena Centre for Systems Biology of Aging, the German Research Association and the Swiss National Science Foundation.
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