Functional characterization of the extranasal OR2A4/7 expressed in human melanocytes

Olfactory receptors ( OR s) were first described as specialized chemoreceptors in the nasal epithelium. In the last two decades, OR s have also been detected to be functionally expressed and active in different nonolfactory tissues of the human body, because they used to react to specific odour stimuli. In this study, we conducted a characterization of the extranasal OR 2A4/7 expressed in primary human melanocytes and sections of the human skin. OR 2A4/7 expression could be demonstrated at the transcript and protein level. We uncovered elevated intracellular cAMP and Ca 2+ levels accompanied by elevated p38 and reduced p42/44 MAPK phosphorylation following odourant (cyclohexyl salicylate; CHS ) stimulation of melanocytes. These results were associated with enhanced melanin biosynthesis in conjunction with the growth inhibition and differentiation of melanocytes. Our findings highlight the participation of OR 2A4/7 in human primary melanocyte physiology and suggest an alternate mechanism that regulates melanogenesis.