CXCR 7 mediates SDF 1‐induced melanocyte migration

Summary Melanoblasts are derived from the neural crest and migrate to the dermal/epidermal border of skin and hair bulges. Although melanoblast migration during embryogenesis has been well investigated, there are only a few reports regarding the migration of mature melanocytes. Here, we demonstrate that a chemokine, stromal‐derived factor‐1 ( SDF 1, also known as CXCL 12), and one of its receptor CXCR 7 regulate normal human epidermal melanocyte ( NHEM ) migration. We found that SDF 1 induces the directional migration of NHEM s. Interestingly, although both CXCR 4 and CXCR 7 are expressed in NHEM s, blockade of CXCR 4 using a CXCR 4‐specific neutralizing antibody did not exert any influence on the SDF 1‐induced migration of NHEM s, whereas blockade of CXCR 7 using a CXCR 7‐specific neutralizing antibody did influence migration. Furthermore, SDF 1‐induced NHEM s migration exhibited the early hallmark events of CXCR 7 signaling associated with MAP kinase activation. It is known that the phosphorylation of ERK through CXCR 7 signaling is mediated by β‐arrestins. The treatment of NHEM s with SDF 1 resulted in the phosphorylation of ERK in a β‐arrestin 2‐dependent manner. These results suggest that melanocytes may have a unique mechanism of migration via SDF 1/ CXCR 7 signaling that is different from that of other cell types.