By Alice Park – Time.com
It’s been 13 years in the making, but Dr. David Sinclair and his colleagues have finally answered the question of what drives aging. In a study published Jan. 12 in Cell, Sinclair, a professor of genetics and co-director of the Paul F. Glenn Center for Biology of Aging Research at Harvard Medical School, describes a groundbreaking aging clock that can speed up or reverse the aging of cells.
Scientists studying aging have debated what drives the process of senescence in cells—and primarily focused on mutations in DNA that can, over time, mess up a cell’s normal operations and trigger the process of cell death. But that theory wasn’t supported by the fact that older people’s cells often were not riddled with mutations, and that animals or people harboring a higher burden of mutated cells don’t seem to age prematurely.
Sinclair therefore focused on another part of the genome, called the epigenome. Since all cells have the same DNA blueprint, the epigenome is what makes skin cells turn into skin cells and brain cells into brain cells. It does this by providing different instructions to different cells for which genes to turn on, and which to keep silent. Epigenetics is similar to the instructions dressmakers rely on from patterns to create shirts, pants, or jackets. The starting fabric is the same, but the pattern determines what shape and function the final article of clothing takes. With cells, the epigenetic instructions lead to cells with different physical structures and functions in a process called differentiation.
