title: Gene structure of the goldfish agouti-signaling protein: a putative role in the dorsal-ventral pigment pattern of fish.
abstract: One of the most successful chromatic adaptations in vertebrates is the dorsal-ventral pigment pattern in which the dorsal skin is darkly colored, whereas the ventrum is light. In fish, the latter pattern is achieved because a melanization inhibition factor inhibits melanoblast differentiation and supports iridophore proliferation in the ventrum. In rodents, the patterned pigmentation results from regional production of the agouti-signaling protein (ASP). This peptide controls the switch between production of eumelanin and pheomelanin by antagonizing alphaMSH effects on melanocortin receptor (MCR) 1 in the melanocytes. In addition, ASP inhibits the differentiation and proliferation of melanoblast. Thus, the mammalian ASP may be homologous to the poikilotherm melanization inhibition factor. By screening of a genomic library, we deduced the amino acid sequence of goldfish ASP. The ASP gene is a four-exon gene spanning 3097 bp that encodes a 125-amino acid precursor. Northern blot analysis identified two different ASP mRNAs in ventral skin of red- and black-pigmented and albino fish, but no expression levels were observed in the dorsal skin of the same fish. The dorsal-ventral expression polarity was also detected in both black dorsally pigmented fish and albino fish. Pharmacological studies demonstrate that goldfish ASP acts as a melanocortin antagonist at Fugu MC1R and goldfish MC4R. In addition, goldfish ASP inhibited Nle4, D-Phe7-MSH-stimulated pigment dispersion in medaka melanophores. Our studies support agouti signaling protein as the melanization inhibition factor, a key factor in the development of the dorsal-ventral pigment pattern in fish.
authors.affiliation: Department of Fish Reproductive Physiology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Cientificas, 12595 Torre de la Sal, Ribera de Cabanes, Castellón, Spain. cerdarev@iats.csic.es
authors.forename: José Miguel
authors.initials: JM
authors.lastname: Cerdá-Reverter
authors.forename: Tatjana
authors.initials: T
authors.lastname: Haitina
authors.forename: Helgi Birgir
authors.initials: HB
authors.lastname: Schiöth
authors.forename: Richard Ector
authors.initials: RE
authors.lastname: Peter
mesh_terms: D054366:Agouti Signaling Protein; D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001667:Binding, Competitive; D001681:Biological Assay; D015152:Blotting, Northern; D015139:Blotting, Southern; D002454:Cell Differentiation; D002460:Cell Line; D049109:Cell Proliferation; D003001:Cloning, Molecular; D017077:Culture Media, Conditioned / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D004247:DNA / Q000737:chemistry; D004996:Ethidium / Q000494:pharmacology; D005260:Female; D015723:Gene Library; D005822:Genetic Vectors; D006054:Goldfish; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis* / Q000235:genetics*; D008024:Ligands; D008297:Male; D008543:Melanins / Q000378:metabolism; D008969:Molecular Sequence Data; D020033:Protein Isoforms; D012313:RNA / Q000737:chemistry; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D023741:Takifugu; D014018:Tissue Distribution; D014162:Transfection; D000521:alpha-MSH / Q000378:metabolism
chemical_list: D054366:Agouti Signaling Protein; D017077:Culture Media, Conditioned; D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; D008543:Melanins; D020033:Protein Isoforms; D012333:RNA, Messenger; C018362:pheomelanin; C041877:eumelanin; D000521:alpha-MSH; D012313:RNA; D004247:DNA; D000242:Cyclic AMP; D004996:Ethidium