Fatty acid-binding protein (fabp) genes of spotted green pufferfish (Tetraodon nigroviridis): comparative genomics and spatial transcriptional regulation

Introduction The members of the family of intracellular lipid-binding proteins (iLBP) are known to play vital roles in the transport of hydrophobic ligands such as long-chain fatty acids and retinoid [...]
The fatty acid-binding protein (fabp) genes belong to the multigene family of intracellular lipid-binding proteins. To date, 12 different FABPs have been identified in vertebrate genomes. Owing to the teleost-specific genome duplication event, many fishes have duplicated copies of the fabp genes. Here, we identified and characterized the fabp genes of spotted green pufferfish (Tetraodon nigroviridis). Seven fabp genes were identified, out of which, two were retained in the pufferfish genome as duplicated copies. Each putative pufferfish Fabp protein shares greatest sequence identity and similarity with their teleost and tetrapod orthologs, and clustered together as a distinct clade in phylogenetic analysis. Conserved gene synteny was evident between the pufferfish fabp genes and the orthologs of human, zebrafish, three-spined stickleback, and medaka FABP/fabp genes, providing evidence that the duplicated copies of pufferfish fabp genes most likely arose as a result of the teleost- specific genome duplication event. The differential tissue-specific distribution of pufferfish fabp transcripts suggests divergent spatial regulation of duplicated pairs of fabp genes. Key words: spotted green pufferfish, fatty acid-binding protein, teleost-specific genome duplication. Les genes codant pour des proteines de liaison aux acides gras (fabp) appartiennent a une famille multigenique de proteines intracellulaires de liaison des lipides. A ce jour, 12 FABP differents ont ete identifies au sein des genomes de vertebres. En raison de l'evenement de duplication genomique specifique des teleosteens, plusieurs poissons ont des copies dupliquees des genes fabp. Dans ce travail, les auteurs identifient et caracterisent les genes fabp chez le tetraodon vert (Tetraodon nigroviridis). Sept genes fapb ont ete identifies, dont deux representent des copies dupliquees qui ont ete conservees au sein du genome du tetraodon. Chaque proteine Fabp putative chez le tetraodon presente une identite et une similarite maximale avec son orthologue chez les teleosteens et les tetrapodes, de maniere a former un clade distinct en analyse phylogenetique. Une syntenie genique etait evidente entre les genes fabp du tetraodon et leurs orthologues chez l'humain, le poisson zebre, l'epinoche a trois epines et le medaka, ce qui suggere que les copies dupliquees des genes FABP/fabp chez le tetraodon sont vraisemblablement le resultat de l'evenement de duplication genomique specifique des teleosteens. La distribution tissus-specifique differentielle des transcrits fabp suggere une regulation spatiale divergente des paires de genes fabp dupliques. [Traduit par la Redaction] Mots-cles: tetraodon vert, proteine de liaison des acides gras, duplication genomique specifique des teleosteens.