LPS induces melanogenesis through p38 MAPK activation in human melanocytes.

We have observed that lipopolysaccharide (LPS) induces pigmentation in melanocytes and in this study have examined whether these responses are mediated by the p38 mitogen-activated protein kinase (MAPK) signaling pathway. LPS appears to stimulate the pigmentation of melanocytes and cultured skin. LPS was found to induce the expression of microphthalmia-associated transcription factor (MITF) and tyrosinase protein in cells. Stimulation of melanocytes with LPS led to time dependent phosphorylation of p38 MAPK. Furthermore, p38 MAPK functionally regulated the LPS-induced melanin formation in melanocytes; a p38 MAPK inhibitor, SB203580, almost completely attenuated the LPS-mediated up-regulation of melanin synthesis and induction of MITF and tyrosinase expression. These findings indicate that activation of p38 MAPK plays an important role in LPS-induced melanogenesis by up-regulating MITF and tyrosinase expression.