STEM CELLS Controlled Mobilization

Tissue stem cells have the capacity to self-renew and generate differentiated cells that replace lost cells as an organism ages. Quiescent stem cells typically reside in specific microenvironments or "niches." When needed, they begin proliferating and exit the niche, a process thought to be controlled by extracellular cues from the niche and by intrinsic genetic programs. Studying mouse models, Flores et al. now show that epidermal stem cell mobilization is regulated by telomeres, the nucleoprotein structures at the ends of chromosomes. Short telomeres impaired mobilization, whereas overexpression of telomerase, the enzyme that synthesizes telomeres, promoted mobilization. The effect of telomeres on stem cell function could potentially explain, at least in part, their role in aging and cancer.

I. Flores, M. L. Cayuela, M. A. Blasco, Effects of telomerase and telomere length on epidermal stem cell behavior. Science 309, 1253-1256 (2005). [Abstract] [Full Text]

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