title: Evolution of the duplicated intracellular lipid-binding protein genes of teleost fishes.
abstract: Increasing organismal complexity during the evolution of life has been attributed to the duplication of genes and entire genomes. More recently, theoretical models have been proposed that postulate the fate of duplicated genes, among them the duplication-degeneration-complementation (DDC) model. In the DDC model, the common fate of a duplicated gene is lost from the genome owing to nonfunctionalization. Duplicated genes are retained in the genome either by subfunctionalization, where the functions of the ancestral gene are sub-divided between the sister duplicate genes, or by neofunctionalization, where one of the duplicate genes acquires a new function. Both processes occur either by loss or gain of regulatory elements in the promoters of duplicated genes. Here, we review the genomic organization, evolution, and transcriptional regulation of the multigene family of intracellular lipid-binding protein (iLBP) genes from teleost fishes. Teleost fishes possess many copies of iLBP genes owing to a whole genome duplication (WGD) early in the teleost fish radiation. Moreover, the retention of duplicated iLBP genes is substantially higher than the retention of all other genes duplicated in the teleost genome. The fatty acid-binding protein genes, a subfamily of the iLBP multigene family in zebrafish, are differentially regulated by peroxisome proliferator-activated receptor (PPAR) isoforms, which may account for the retention of iLBP genes in the zebrafish genome by the process of subfunctionalization of cis-acting regulatory elements in iLBP gene promoters.
authors.affiliation: Department of Biology, Dalhousie University, 1355 Oxford Street, PO BOX 15000, Halifax, NS, B3H 4R2, Canada.
authors.forename: Ananda B
authors.initials: AB
authors.lastname: Venkatachalam
authors.affiliation: Department of Biology, Dalhousie University, 1355 Oxford Street, PO BOX 15000, Halifax, NS, B3H 4R2, Canada.
authors.forename: Manoj B
authors.initials: MB
authors.lastname: Parmar
authors.affiliation: Department of Biology, Dalhousie University, 1355 Oxford Street, PO BOX 15000, Halifax, NS, B3H 4R2, Canada. jmwright@dal.ca.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Wright
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002994:Clofibrate / Q000494:pharmacology; D019143:Evolution, Molecular; D050556:Fatty Acid-Binding Proteins / Q000235:genetics*; D020440:Gene Duplication / Q000235:genetics; D005786:Gene Expression Regulation / Q000235:genetics; D020131:Genes, Duplicate / Q000235:genetics; D005810:Multigene Family / Q000235:genetics; D009990:Oryzias / Q000235:genetics*; D047493:PPAR alpha / Q000819:agonists / Q000235:genetics*; D047495:PPAR gamma / Q000819:agonists / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012177:Retinol-Binding Proteins / Q000235:genetics*; D023701:Smegmamorpha / Q000235:genetics*; D023721:Tetraodontiformes / Q000235:genetics*; D015533:Transcriptional Activation / Q000235:genetics; D015027:Zebrafish / Q000235:genetics*
chemical_list: D050556:Fatty Acid-Binding Proteins; D047493:PPAR alpha; D047495:PPAR gamma; D012177:Retinol-Binding Proteins; D002994:Clofibrate
keywords: Duplicated genes; Fatty acid- and retinoid-binding proteins; Peroxisome proliferator-activated receptor; Subfunctionalization and neofunctionalization; Teleost fishes; Whole genome duplication