title: Divergent evolution of cis-acting peroxisome proliferator-activated receptor elements that differentially control the tandemly duplicated fatty acid-binding protein genes, fabp1b.1 and fabp1b.2, in zebrafish.
abstract: Gene duplication is thought to facilitate increasing complexity in the evolution of life. The fate of most duplicated genes is nonfunctionalization: functional decay resulting from the accumulation of mutations. According to the duplication-degeneration-complementation (DDC) model, duplicated genes are retained by subfunctionalization, where the functions of the ancestral gene are sub-divided between duplicate genes, or by neofunctionalization, where one of the duplicates acquires a new function. Here, we report the differential regulation of the zebrafish tandemly duplicated fatty acid-binding protein genes, fabp1b.1 and fabp1b.2, by peroxisome proliferator-activated receptors (PPAR). fabp1b.1 mRNA levels were induced in tissue explants of liver, but not intestine, by PPAR agonists. fabp1b.1 promoter activity was induced to a greater extent by rosiglitazone (PPARγ-selective agonist) compared to WY 14,643 (PPARα-selective agonist) in HEK293A cells. Mutation of a peroxisome proliferator response element (PPRE) at -1232 bp in the fabp1b.1 promoter reduced PPAR-dependent activation. fabp1b.2 promoter activity was not affected by PPAR agonists. Differential regulation of the duplicated fabp1b promoters may be the result of PPRE loss in fabp1b.2 during a meiotic crossing-over event. Retention of PPAR inducibility in fabp1b.1 and not fabp1b.2 suggests unique regulation and function of the fabp1b duplicates.
authors.affiliation: a Department of Pharmacology, Dalhousie University, Halifax, NS, Canada.
authors.forename: Robert B
authors.initials: RB
authors.lastname: Laprairie
authors.affiliation: a Department of Pharmacology, Dalhousie University, Halifax, NS, Canada.
authors.forename: Eileen M
authors.initials: EM
authors.lastname: Denovan-Wright
authors.affiliation: b Department of Biology, Dalhousie University, Halifax, NS, Canada.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Wright
mesh_terms: D000818:Animals; D001483:Base Sequence; D019143:Evolution, Molecular; D050556:Fatty Acid-Binding Proteins / Q000235:genetics*; D020440:Gene Duplication; D020131:Genes, Duplicate; D014644:Genetic Variation; D057809:HEK293 Cells; D006801:Humans; D009154:Mutation; D047492:Peroxisome Proliferator-Activated Receptors / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D014162:Transfection; D015027:Zebrafish / Q000235:genetics*; D029961:Zebrafish Proteins / Q000235:genetics*
chemical_list: D050556:Fatty Acid-Binding Proteins; D047492:Peroxisome Proliferator-Activated Receptors; D012333:RNA, Messenger; D029961:Zebrafish Proteins; C513421:fatty acid-binding protein 1b, zebrafish
keywords: duplication génique; duplication–degeneration–complementation; duplication–dégénérescence–complémentation; fatty acid-binding protein; gene duplication; peroxisome proliferator-activated receptor; promoter; promoteur; protéine de liaison aux acides gras; récepteur activés par les proliférateurs de peroxysomes