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P-Locus Is a Target for the Melanogenic Effects of MC-1R Signaling

A Possible Control Point for Facultative Pigmentation


Address for correspondence: Janis Ancans, Department of Biomedical Sciences, University of Bradford, United Kingdom. Voice: 371-6494422; fax: 371-7323403.


Abstract: Melanocortin receptor type 1 (MC-1R) is an important control point for ultraviolet ray (UVR)-induced tanning response in the skin. In this study, we show that p-locus is a downstream target for MC-1R signaling. The expression of p-locus was up-regulated by α-MSH as well as db-cAMP, a syn-thetic analogue of cAMP that mimics activation of MC-1R. Furthermore, p-locus transcript abundance was significantly increased in epidermal melanocytes of white skin with facultative (UVR-induced) pigmentation. Because p-locus product is essential for pigmentation and also has been shown to be highly polymorphic in human population, we propose that the pigmentary response to the melanocortin peptides/UVR would be affected not only by MC-1R mutations but also by the functionality of p-locus product. These factors together could account for the many different levels of tanning ability seen in the white population.