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.

Tracing the evolution of fatty acid‐binding proteins (FABPs) in organisms with a heterogeneous fat distribution

“…Together with the conserved FABP gene synteny analysis, we confirmed that the current FABP family gene/protein set might have resulted from multiple rounds of duplications and splicing editing divergence during evolution. These results regarding FABP evolution are consistent with the reports of Schaap [25] and M. Wright [35].…”

“…Conserved synteny (the colocalization of genes on chromosomes) is sometimes used to describe the preservation of the precise order of genes on a chromosome passed down from a common ancestor [32], although many geneticists reject this use of the term [33]. Many studies have indicated that all FABPs are likely to have arisen from common ancestral genes through duplication and diversification [25,34,35]. Thus, we analyzed the synteny of FABP family genes.…”

“…As shown by the studies of M. Wright and his colleagues [35‐36,38‐41], teleost fishes possess many copies of fabps genes owing to a whole‐genome duplication even that occurred early in the teleost radiation. In addition, these authors proposed that the two copies of fabp7a/fabp7b , fabp10a/fabp10b, and fabp11a/fabp11b in the teleost fish genome may have resulted from a fish‐specific duplication event [29,39], although the duplicated zebrafish fabp1b.1 and fabp1b.2 sequences are tandemly arrayed on chromosome 8.…”

“…In addition, these authors proposed that the two copies of fabp7a/fabp7b , fabp10a/fabp10b, and fabp11a/fabp11b in the teleost fish genome may have resulted from a fish‐specific duplication event [29,39], although the duplicated zebrafish fabp1b.1 and fabp1b.2 sequences are tandemly arrayed on chromosome 8. The fabp1b.1 and fabp1b.2 genes of zebrafish are paralogs that were presumably duplicated by unequal crossing‐over during meiosis [35].…”

Genome-Wide Analysis of the FABP Gene Family in Liver of Chicken (Gallus gallus): Identification, Dynamic Expression Profile, and Regulatory Mechanism

“…This FABP diversity likely arose from the two successive rounds of whole genome duplication (WGD) that occurred in early vertebrates [53,54]. In contrast, FABP9 and FABP12 appear restricted to mammals [55], but FABP10 has been proposed in avian and teleost [56], revealing the relevance of FABP gene degeneration or duplication in the divergence of these chicken FABP genes from those of other vertebrates [23,53]. A previous study suggested FABP10 originated before the most recent common ancestor (MRCA) of tetrapod and bony fish [23].…”