Melanocortin 1 receptor and skin pathophysiology: beyond colour, much more than meets the eye

The melanocortin 1 receptor ( MC 1R), a G protein‐coupled receptor preferentially expressed in melanocytes, mediates the pigmentary effects of α melanocyte‐stimulating hormone ( α MSH ). MC 1R is also expressed in other cutaneous cell types, particularly keratinocytes and dermal fibroblasts, suggesting non‐pigmentary actions of the α MSH / MC 1R system. Böhm and Stegemann now report a dramatic effect of mouse Mc1r functional status on susceptibility to skin fibrosis and collagen types I and III metabolism, in a study combining the powerful mouse model provided by the natural Mc1r e/e knockout and an established model of skin fibrosis. The study underscores the antifibrotic role for the skin α MSH / MC 1R system.