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

The melanocortin 1 receptor (MC1R), a G protein‐coupled receptor preferentially expressed in melanocytes, mediates the pigmentary effects of α melanocyte‐stimulating hormone (αMSH). MC1R is also expressed in other cutaneous cell types, particularly keratinocytes and dermal fibroblasts, suggesting non‐pigmentary actions of the αMSH/MC1R 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 αMSH/MC1R system.