title: Agouti signaling protein and other factors modulating differentiation and proliferation of immortal melanoblasts.
abstract: The melanocyte lineage potentially forms an attractive model system for studies in cell differentiation, developmental genetics, cell signaling, and melanoma, because differentiated cells produce the visible pigment melanin. Immortal lines of murine melanoblasts (melanocyte precursors) have been described previously, but induction of differentiation involved a complex culture system with keratinocyte feeder cells. Here we describe conditions for both growth and induced differentiation of the melanoblast line melb-a, without feeder cells, and analyze factors that directly control proliferation and differentiation of these pure melanoblasts. Several active factors are products of developmental and other coat color genes, including stem cell factor (SCF), melanocyte-stimulating hormone (alphaMSH), and agouti signaling protein (ASP), a natural antagonist at the MSH receptor (melanocortin 1 receptor, MC1R) encoded by the agouti gene. A stable analog of alphaMSH (NDP-MSH) stimulated differentiation and inhibited growth. ASP in excess inhibited both effects of NDP-MSH, that is, ASP could inhibit pigmentation and stimulate growth. These effects provide an explanation for the interactions in mice of melanocyte developmental mutations with yellow agouti and Mc1r alleles, and a role for embryonic expression patterns of ASP.
authors.affiliation: Department of Anatomy and Developmental Biology, St George's Hospital Medical School, London, United Kingdom. esviders@sghms.ac.uk
authors.forename: E V
authors.initials: EV
authors.lastname: Sviderskaya
authors.forename: S P
authors.initials: SP
authors.lastname: Hill
authors.forename: D
authors.initials: D
authors.lastname: Balachandar
authors.forename: G S
authors.initials: GS
authors.lastname: Barsh
authors.forename: D C
authors.initials: DC
authors.lastname: Bennett
mesh_terms: D054366:Agouti Signaling Protein; D000818:Animals; D002454:Cell Differentiation; D002455:Cell Division; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D036341:Intercellular Signaling Peptides and Proteins; D015603:Keratinocytes / Q000378:metabolism; D008543:Melanins / Q000378:metabolism; D008544:Melanocytes / Q000166:cytology* / Q000378:metabolism*; D051379:Mice; D010858:Pigmentation / Q000235:genetics; D011506:Proteins / Q000235:genetics* / Q000494:pharmacology; D015398:Signal Transduction; D000521:alpha-MSH / Q000494:pharmacology
chemical_list: D054366:Agouti Signaling Protein; D036341:Intercellular Signaling Peptides and Proteins; D008543:Melanins; D011506:Proteins; D000521:alpha-MSH