The end of a chromosome may hold the beginning of a clearer understanding of how humans age. Shay and Wright are the first to report this important finding. They received an AlliedSignal Award for Research on Aging to explore this line of research last year.
Telomeres are specialized structures that are important in maintaining chromosomal stability.
Each time a cell divides, its telomeres shorten. Eventually, the telomeres get so short that normal cells stop dividing. This study is strong evidence that telomere length is the clock that counts cell divisions. The expression of the enzyme telomerase maintains stable telomere length. Telomerase is not detected in normal cells and telomeres shorten and then the cells stop dividing and enter a phase called cellular senescence.