title: Macelignan inhibits melanosome transfer mediated by protease-activated receptor-2 in keratinocytes.
abstract: Skin pigmentation is the result of melanosome transfer from melanocytes to keratinocytes. Protease-activated receptor-2 (PAR-2) is a key mediator of melanosome transfer, which occurs as the melanocyte extends its dendrite toward surrounding keratinocytes that take up melanosomes by phagocytosis. We investigated the effects of macelignan isolated from Myristica fragrans HOUTT. (nutmeg) on melanosome transfer and the regulation of PAR-2 in human keratinocytes (HaCaT). HaCaT cells stimulated by the PAR-2-activating peptide Ser-Leu-Ile-Gly-Arg-Leu-NH₂ (SLIGRL) were treated with macelignan; PAR-2 expression was then determined by reverse transcription-polymerase chain reaction (RT-PCR), Western blot, and immunocytochemistry. We evaluated the effects of macelignan on calcium mobilization and keratinocyte phagocytosis. In addition, B16F10 melanoma cells and keratinocytes were co-cultured to assess the effects of macelignan on prostaglandin E₂ (PGE₂) secretion and subsequent dendrite formation. Macelignan decreased HaCaT PAR-2 mRNA and protein levels in a dose-dependent manner. Furthermore, macelignan markedly reduced intracellular calcium mobilization and significantly downregulated keratinocyte phagocytosis, as shown by decreased ingestion of Escherichia coli bioparticles and fluorescent microspheres. In co-culture experiments, macelignan reduced keratinocyte PGE₂ secretion, thereby preventing dendrite formation in B16F10 melanoma cells compared with SLIGRL-treated controls. Macelignan inhibits melanosome transfer by downregulating PAR-2, thereby reducing keratinocyte phagocytosis and PGE₂ secretion, which in turn inhibits dendrite formation in B16F10 melanoma cells. Taken together, our findings suggest that macelignan could be used as a natural depigmenting agent to ameliorate hyperpigmentation.
authors.affiliation: Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Japan.
authors.forename: Eun-Jung
authors.initials: EJ
authors.lastname: Choi
authors.forename: Young-Gyu
authors.initials: YG
authors.lastname: Kang
authors.forename: Jaekyung
authors.initials: J
authors.lastname: Kim
authors.forename: Jae-Kwan
authors.initials: JK
authors.lastname: Hwang
mesh_terms: D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002460:Cell Line; D017931:DNA Primers; D006801:Humans; D007150:Immunohistochemistry; D015603:Keratinocytes / Q000187:drug effects* / Q000378:metabolism; D017705:Lignans / Q000494:pharmacology*; D020460:Melanosomes / Q000187:drug effects* / Q000378:metabolism; D044464:Receptor, PAR-2 / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D017931:DNA Primers; D017705:Lignans; D044464:Receptor, PAR-2; C502026:macelignan