What makes us age? Ticking of cellular clock promotes seismic changes in chromatin landscape associated with aging

ScienceDaily (2010-10-04) -- Like cats, human cells have a finite number of lives: once they divide a certain number of times (thankfully, more than nine) they change shape, slow their pace, and eventually stop dividing -- a phenomenon called "cellular senescence." Biologists know that a cellular clock composed of structures at the chromosome end known as telomeres records how many "lives" a cell has expended. Up to now, investigators have not yet defined how the clock's ticking signals the approach of cellular oblivion.