Melanocortin 1 receptor (MC1R) (MC1R)

The Melanocortin 1 receptor (MC1R) is a G protein-coupled receptor (GPCR) primarily expressed on the surface of melanocytes, where it serves as the master regulator of skin and hair pigmentation. It is activated by the binding of alpha-melanocyte-stimulating hormone (alpha-MSH) and adrenocorticotropic hormone (ACTH), initiating a signaling cascade that promotes the production of eumelanin over pheomelanin, which is critical for photoprotection and DNA repair in the skin. The input 'Melanocyte production promotion' describes this physiological process or a therapeutic goal rather than a specific molecular target, but MC1R is the primary receptor through which such promotion is pharmacologically achieved. Genetic polymorphisms in the MC1R gene are major determinants of individual variations in skin color and are strongly associated with the 'red hair color' (RHC) phenotype, which carries an increased risk for both melanoma and non-melanoma skin cancers due to reduced photoprotective melanin production. Beyond pigmentation, MC1R signaling is involved in anti-inflammatory pathways and may influence pain perception. Therapeutic targeting of MC1R is currently utilized for conditions such as erythropoietic protoporphyria to provide photoprotection and is being investigated for the treatment of vitiligo and other pigmentary disorders.

Other names

Melanocyte-stimulating hormone receptorMSH-RMelanotropin receptorMC1-RCMM5SHEP2

Activation of the Melanocortin 1 receptor (MC1R) by agonists like alpha-melanocyte-stimulating hormone (alpha-MSH) triggers the Gs protein-adenylyl cyclase pathway, increasing intracellular cAMP levels. This elevation activates protein kinase A (PKA), which phosphorylates CREB, leading to the upregulation of the Microphthalmia-associated transcription factor (MITF). MITF subsequently increases the expression of melanogenic enzymes such as tyrosinase, promoting the synthesis and distribution of eumelanin within melanocytes.