title: UV light phototransduction depolarizes human melanocytes.
abstract: Exposure of human skin to low doses of solar UV radiation (UVR) causes increased pigmentation, while chronic exposure is a powerful risk factor for skin cancers. The mechanisms mediating UVR detection in skin, however, remain poorly understood. Our recent studies revealed that UVR activates a retinal-dependent G protein-coupled signaling pathway in melanocytes. This phototransduction pathway leads to the activation of transient receptor potential A1 (TRPA1) ion channels, elevation of intracellular calcium (Ca( 2+)) and rapid increase in cellular melanin content. Here we report that physiological doses of solar-like UVR elicit a retinal-dependent membrane depolarization in human epidermal melanocytes. This transient depolarization correlates with delayed inactivation time of the UVR-evoked photocurrent and with sustained Ca( 2+) responses required for early melanin synthesis. Thus, the cellular depolarization induced by UVR phototransduction in melanocytes is likely to be a critical signaling mechanism necessary for the protective response represented by increased melanin content.
authors.affiliation: Department of Molecular Pharmacology, Physiology, and Biotechnology; Brown University; Providence, RI USA.
authors.forename: Nicholas W
authors.initials: NW
authors.lastname: Bellono
authors.forename: Elena
authors.initials: E
authors.lastname: Oancea
mesh_terms: D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism; D004307:Dose-Response Relationship, Radiation; D000078404:Epidermal Cells; D006801:Humans; D055537:Light Signal Transduction / Q000528:radiation effects*; D008543:Melanins / Q000096:biosynthesis; D008544:Melanocytes / Q000166:cytology* / Q000378:metabolism / Q000528:radiation effects*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D000074025:TRPA1 Cation Channel; D050051:Transient Receptor Potential Channels / Q000378:metabolism; D014466:Ultraviolet Rays / Q000009:adverse effects*
chemical_list: D015220:Calcium Channels; D008543:Melanins; D009419:Nerve Tissue Proteins; D000074025:TRPA1 Cation Channel; C473350:TRPA1 protein, human; D050051:Transient Receptor Potential Channels; D002118:Calcium
keywords: UV; calcium signaling; melanocyte; phototransduction; ultraviolet