title: Production of the soluble form of KIT, s-KIT, abolishes stem cell factor-induced melanogenesis in human melanocytes.
abstract: The signaling of stem cell factor (SCF) and its receptor KIT (membrane-bound KIT; m-KIT) plays an important role in melanocyte development, survival, proliferation, and melanogenesis. It has been demonstrated in other systems that a soluble form of m-KIT released from the cell surface (s-KIT) regulates SCF signaling, although there have been no reports pertaining to the existence and the biological role of s-KIT in melanocytes. In this study, we therefore examined the involvement of s-KIT in melanogenesis. Western blotting analysis revealed that treatment with phorbol 12-myristate-13-acetate (PMA) or 4-aminophenylmercuric acetate (APMA) induced s-KIT production in cultured human melanocytes. Inhibitors of tumor necrosis factor-alpha-converting enzyme (TACE) and metalloproteinases (MMPs) muted this release of s-KIT into the media. Human recombinant s-KIT added to melanocytes inhibited SCF-induced phosphorylation of m-KIT, resulting in suppression of SCF-induced melanogenesis. Additionally, APMA-induced s-KIT production abolished SCF-induced melanogenesis as effectively as a KIT-neutralizing antibody. Concomitantly, APMA and TACE inhibitors significantly decreased and increased melanin synthesis, respectively, in an in vitro skin model. Taken together, these findings provided an insight into the elaborate mechanism of SCF/m-KIT signaling in human melanocytes and suggested that production of s-KIT contributes to the regulation of human skin pigmentation. Journal of Investigative Dermatology (2008) 128, 1763-1772; doi:10.1038/jid.2008.9; published online 31 January 2008.
authors.affiliation: Kao Biological Science Laboratories, Tochigi, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Kasamatsu
authors.forename: Akira
authors.initials: A
authors.lastname: Hachiya
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Higuchi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ohuchi
authors.forename: Takashi
authors.initials: T
authors.lastname: Kitahara
authors.forename: Raymond E
authors.initials: RE
authors.lastname: Boissy
mesh_terms: D051722:ADAM Proteins / Q000502:physiology; D000072198:ADAM17 Protein; D002478:Cells, Cultured; D006801:Humans; D020782:Matrix Metalloproteinases / Q000502:physiology; D008543:Melanins / Q000096:biosynthesis*; D008544:Melanocytes / Q000378:metabolism*; D010766:Phosphorylation; D019009:Proto-Oncogene Proteins c-kit / Q000502:physiology*; D015398:Signal Transduction; D012867:Skin / Q000378:metabolism; D012880:Skin Pigmentation; D019089:Stem Cell Factor / Q000037:antagonists & inhibitors* / Q000502:physiology
chemical_list: D008543:Melanins; D019089:Stem Cell Factor; D019009:Proto-Oncogene Proteins c-kit; D051722:ADAM Proteins; D020782:Matrix Metalloproteinases; D000072198:ADAM17 Protein; C000606462:ADAM17 protein, human