UVB represses melanocyte cell migration and acts through β‐catenin

Abstract The exposure of skin to ultraviolet ( UV ) radiation can have both beneficial and deleterious effects: it can lead, for instance, to increased pigmentation and vitamin D synthesis but also to inflammation and skin cancer. UVB may induce genetic and epigenetic alterations and have reversible effects associated with post‐translational and gene regulation modifications. β‐catenin is a main driver in melanocyte development; although infrequently mutated in melanoma, its cellular localization and activity are frequently altered. Here, we evaluate the consequence of UVB on β‐catenin in the melanocyte lineage. We report that in vivo , UVB induces cytoplasmic/nuclear relocalization of β‐catenin in melanocytes of newborn mice and adult human skin. In mouse melanocyte and human melanoma cell lines in vitro, UVB increases β‐catenin stability, accumulation in the nucleus and cotranscriptional activity, leading to the repression of cell motility and velocity. The activation of the β‐catenin signalling pathway and its effect on migration by UVB are increased by an inhibitor of GSK 3β, and decreased by an inhibitor of β‐catenin. In conclusion, UVB represses melanocyte migration and does so by acting through the GSK 3‐β‐catenin axis.