On Nov 30, 2010, at 1:58 PM, "larry.r.trout
'Aging is generally accompanied by a gradual decline in cellular and organ functioning that eventually results in increased mortality risk. One proposed mechanism for aging focuses on telomere maintenance. Telomeres are the ends of chromosomes that, for mechanical reasons, require a special copying enzyme. Human germ cells produce a complex called telomerase to maintain telomere length; other human cells do not. As a result, the telomeres of most cells get shorter with each cell division. Eventually, their reduced length activates DNA damage signaling pathways that induce the cell to enter a sort of senescence…
Ron DePinho and his colleagues have just added telomerase back into these telomerase deficient mice to see if this would halt, or possibly even reverse, the tissue degeneration. Their report appears in Nature.
First, they determined that the reinstated telomerase works; when it was induced in cultured cells, it elongated telomeres. Moreover, the cells were no longer subjected to DNA damage signals, so they resumed proliferating. '