Telomere Length: Cause of Aging or Marker of Aging?

Telomeres are repeating sequences of nucleic acids that cap the ends of chromosomes in the cell nucleus and stop actual gene-coding DNA from being chopped off when a cell divides. The mechanisms of DNA replication require extra leg room at the ends of the strand, a trailing sequence that is not copied over to the new strand under assembly - and the primary role of telomeres is to be the part that is dropped on the floor. A little of their length is thus lost with every cell division. This shortening acts as a clock to count cell divisions, and cells with very short telomeres stop replicating - they either enter cellular senescence (which ideally then causes the immune system to destroy them) or destroy themselves directly via programmed cell death mechanisms. Telomere length is more dynamic than this simple picture, however. In some cell populations, such as the various types of stem cell that maintain tissues and produce new cells to replace those lost or damaged, an enzyme called telomerase continually lengthens telomeres so as to allow a cell lineage to continue dividing indefinitely. Ordinary, non-stem cell populations exhibit a range of telomere lengths, some short, some long. You might imagine that a population of cells replenished more frequently or recently by stem cells will have longer telomeres on average. A population that is receiving less support might have shorter telomeres. Researchers have shown that a higher proportion of short telomeres in white blood cel...
Source: Fight Aging! - Category: Health Medicine and Bioethics Commentators Authors: Tags: Medicine, Biotech, Research Source Type: blogs