title: Neprilysin, a novel target for ultraviolet B regulation of melanogenesis via melanocortins.
abstract: Compelling evidence suggest a role for melanocortins in the regulation of melanogenesis by ultraviolet radiation. Within the epidermis, melanocytes and keratinocytes produce alpha-melanocyte-stimulating hormone and adrenocorticotropic hormone. The persistence and the strength of the biologic signal delivered by these peptides depend on their local concentration, which is controlled by the rate of peptide production and by the rate of its degradation. In this study, we investigated the mechanism of melanocortin degradation by melanocytes and the effect of ultraviolet on this process. We have focused our attention on a neutral endopeptidase, neprilysin, which has been implicated in the ending of numerous peptidergic signals. We have shown that this enzyme is expressed at the surface of human melanocytes. Interestingly, its activity and its expression are dramatically downregulated by ultraviolet B treatment. Moreover, in the presence of phosphoramidon, a stable inhibitor of neprilysin, we observed an increased efficiency of alpha-melanocyte-stimulating hormone and adrenocorticotropic hormone to stimulate both tyrosinase activity and microphthalmia expression. Taken together, these data indicate that neprilysin expressed by melanocytes has a physiologic role in the regulation of melanogenesis by proopiomelanocortin peptide. Further, its downregulation by ultraviolet B irradiation shed light on a new and appealing mechanism of ultraviolet B induced melanogenesis via the control of melanocortins degradation.
authors.affiliation: INSERM U385 and INSERM U526, Faculté de Médecine, Nice, France. eaberdam@unice.fr
authors.forename: E
authors.initials: E
authors.lastname: Aberdam
authors.forename: P
authors.initials: P
authors.lastname: Auberger
authors.forename: J P
authors.initials: JP
authors.lastname: Ortonne
authors.forename: R
authors.initials: R
authors.lastname: Ballotti
mesh_terms: D002478:Cells, Cultured; D015536:Down-Regulation / Q000528:radiation effects; D006801:Humans; D008543:Melanins / Q000096:biosynthesis* / Q000528:radiation effects*; D015260:Neprilysin / Q000502:physiology / Q000528:radiation effects*; D012880:Skin Pigmentation / Q000528:radiation effects; D014466:Ultraviolet Rays; D000521:alpha-MSH / Q000502:physiology*
chemical_list: D008543:Melanins; D000521:alpha-MSH; D015260:Neprilysin