What are telomeres?
At the simplest level, the structures at the end of chromosomes—telomeres—are analogous to the glued tips of shoelaces that prevent the laces from fraying and unraveling. But for researchers, including Nobel Laureate Jack Szostak and Rick Maser at The Jackson Laboratory, there's much more to them than that.
Each time a cell divides, its telomeres get shorter. In most cells, telomeres shorten over time to the point where cell division is no longer possible. Aging is thought to be at least partly due to cells reaching their limit for division, then dying. But some cells, including eggs and sperm, are capable of ongoing division. They contain telomerase, an enzyme that lengthens telomeres.
Why don't all cells have telomerase? Cancer. Shortened telomeres act as a brake on cancer cells' uncontrolled division. Having lots of telomerase in all cells would lead, ironically, to a short, tumor-riddled life. Nonetheless, control of telomerase offers the tantalizing potential to selectively retard aging (by increasing telomerase activity) and/or suppress cancer (by reducing it). Stay tuned.