Specification and loss of melanocyte stem cells

The melanocyte stem cells of the hair follicle provide an attractive system for the study of stem cells. The stem cells exist in an anatomically defined niche clearly separated from their differentiated progeny, differentiated progeny can be selected against by treatment with an inhibitor of Stem Cell Factor signaling, perturbations which affect survival and differentiation have clearly visible pigmentation phenotypes, and genetic mutations can impair or completely abolish this lineage without lethality. In mice several coat color mutants have been shown to have impaired specification or survival of melanocyte stem cells. Furthermore understanding of the normal regulation and behaviors of melanocytes and melanocyte stem cells will allow development of better strategies for cancer treatment. This article will review the discovery and behaviors of melanoctye stem cells as well as some aspects of melanocyte biology.