Gene structure of the goldfish agouti-signaling protein: a putative role in the dorsal-ventral pigment pattern of fish.
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.
Cerdá-Reverter
José Miguel
JM
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
Haitina
Tatjana
T
Schiöth
Helgi Birgir
HB
Peter
Richard Ector
RE
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
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