title: WNT1 and WNT3a promote expansion of melanocytes through distinct modes of action.
abstract: Summary WNT1 and WNT3a have been described as having redundant roles in promoting the development of neural crest-derived melanocytes (NC-Ms). We used cell lineage restricted retroviral infections to examine the effects of WNT signaling on defined cell types in neural crest cultures. RCAS retroviral infections were targeted to melanoblasts (NC-M precursor cells) derived from transgenic mice that express the virus receptor, TVA, under the control of a melanoblast promoter (DCT). As expected, over 90% of DCT-TVA+ cells expressed early melanoblast markers MITF and KIT. However, by following the fate of infected cells in standard culture conditions, we find that only 5% of descendents were NC-Ms. The majority of the descendents were not NC-Ms, but expressed smooth muscle cell markers, demonstrating that mammalian melanoblasts are not committed to the NC-M lineage. RCAS infection of DCT-TVA+ cells demonstrated that overexpression of canonical WNT signaling genes (betaCAT, WNT3a or WNT1) can increase NC-M numbers in an endothelin dependent manner. However, WNT1 and WNT3a have different modes of action with respect to melanoblast fate. Intrinsic over-expression of betaCAT or WNT3a can increase NC-M numbers by biasing the fate of DCT-TVA+ cells to NC-Ms. In contrast, the DCT-TVA+ melanoblasts cannot respond to WNT1 signaling and do not alter their fate towards NC-M. Instead, WNT1 only increases NC-M numbers through paracrine signaling on melanoblast precursors to increase the numbers of neural crest cells that become NC-Ms.
authors.affiliation: Mouse Embryology Section, Genetic Disease Research Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-4472, USA.
authors.forename: Karen Joyce
authors.initials: KJ
authors.lastname: Dunn
authors.forename: Matthew
authors.initials: M
authors.lastname: Brady
authors.forename: Christina
authors.initials: C
authors.lastname: Ochsenbauer-Jambor
authors.forename: Sara
authors.initials: S
authors.lastname: Snyder
authors.forename: Arturo
authors.initials: A
authors.lastname: Incao
authors.forename: William J
authors.initials: WJ
authors.lastname: Pavan
mesh_terms: D000818:Animals; D000943:Antigens, Differentiation / Q000096:biosynthesis; D002454:Cell Differentiation / Q000502:physiology; D019070:Cell Lineage / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000502:physiology*; D008544:Melanocytes / Q000166:cytology / Q000502:physiology*; D051379:Mice; D008817:Mice, Mutant Strains; D008822:Mice, Transgenic; D009130:Muscle, Smooth / Q000166:cytology / Q000502:physiology; D009432:Neural Crest / Q000166:cytology* / Q000196:embryology; D011401:Promoter Regions, Genetic / Q000235:genetics; D011506:Proteins / Q000235:genetics / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology; D051153:Wnt Proteins; D000071818:Wnt-5a Protein; D051155:Wnt1 Protein; D060508:Wnt3 Protein; D060509:Wnt3A Protein
chemical_list: D000943:Antigens, Differentiation; D036341:Intercellular Signaling Peptides and Proteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; C555510:WNT3A protein, human; D051153:Wnt Proteins; D000071818:Wnt-5a Protein; D051155:Wnt1 Protein; C495246:Wnt1 protein, mouse; D060508:Wnt3 Protein; D060509:Wnt3A Protein; C555511:Wnt3a protein, mouse; C438615:Wnt5a protein, mouse