title: oca2 Regulation of chromatophore differentiation and number is cell type specific in zebrafish.
abstract: We characterized a zebrafish mutant that displays defects in melanin synthesis and in the differentiation of melanophores and iridophores of the skin and retinal pigment epithelium. Positional cloning and candidate gene sequencing link this mutation to a 410-kb region on chromosome 6, containing the oculocutaneous albinism 2 (oca2) gene. Quantification of oca2 mutant melanophores shows a reduction in the number of differentiated melanophores compared with wildtype siblings. Consistent with the analysis of mouse Oca2-deficient melanocytes, zebrafish mutant melanophores have immature melanosomes which are partially rescued following treatment with vacuolar-type ATPase inhibitor/cytoplasmic pH modifier, bafilomycin A1. Melanophore-specific gene expression is detected at the correct time and in anticipated locations. While oca2 zebrafish display unpigmented gaps on the head region of mutants 3 days post-fertilization, melanoblast quantification indicates that oca2 mutants have the correct number of melanoblasts, suggesting a differentiation defect explains the reduced melanophore number. Unlike melanophores, which are reduced in number in oca2 mutants, differentiated iridophores are present at significantly higher numbers. These data suggest distinct mechanisms for oca2 in establishing differentiated chromatophore number in developing zebrafish.
authors: School of Molecular Biosciences, Washington State University Vancouver, Vancouver, WA, USA.
authors: Alisha J
authors: AJ
authors: Beirl
authors: Tor H
authors: TH
authors: Linbo
authors: Marea J
authors: MJ
authors: Cobb
authors: Cynthia D
authors: CD
authors: Cooper
mesh_terms: D000818:Animals; D001483:Base Sequence; D002452:Cell Count; D002454:Cell Differentiation / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D002856:Chromatophores / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D017403:In Situ Hybridization; D018942:Macrolides / Q000494:pharmacology; D008543:Melanins / Q000096:biosynthesis; D008547:Melanophores / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D026901:Membrane Transport Proteins / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D014442:Monophenol Monooxygenase / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D009928:Organ Specificity / Q000187:drug effects; D010858:Pigmentation / Q000187:drug effects; D014443:Tyrosine / Q000494:pharmacology; D025262:Vacuolar Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism; D015027:Zebrafish / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000378:metabolism*
chemical_list: D018942:Macrolides; D008543:Melanins; D026901:Membrane Transport Proteins; C000592596:OCA2 protein, zebrafish; D029961:Zebrafish Proteins; D014443:Tyrosine; C040929:bafilomycin A1; D014442:Monophenol Monooxygenase; D025262:Vacuolar Proton-Translocating ATPases
keywords: cell number; chromatophores; differentiation; iridophores; melanophores; oca2