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Genome Biol Evol. 2015 Apr 24;7(5):1332-48. doi: 10.1093/gbe/evv072.

Expanding Duplication of Free Fatty Acid Receptor-2 (GPR43) Genes in the Chicken Genome.

Author information

1
UMR85 Physiologie de la Reproduction et des Comportements, INRA, Nouzilly, France UMR7247, CNRS, Nouzilly, France Université François Rabelais de Tours, France Institut Français du Cheval et de l'Equitation, Nouzilly, France.
2
INRA, UMR1348 Physiologie, Environnement et Génétique pour l'Animal et les Systèmes d'élevage, Saint-Gilles, France Agrocampus-Ouest, UMR1348, Rennes, France.
3
IMPMC, UMR CNRS 7590, Museum National d'Histoire Naturelle, IRD UMR 206, Sorbonne Universités-UPMC Université Paris 06, France.
4
INRA, BIA, CS 52627, Castanet-Tolosan, France.
5
UMR INRA/INPT ENSAT/INPT ENVT, UMR1388 Génétique, Physiologie et Systèmes d'élevage, INRA, Castanet Tolosan, France.
6
INRA, UR 0066 Pharmacologie-Toxicologie, Toulouse, France.
7
UMR85 Physiologie de la Reproduction et des Comportements, INRA, Nouzilly, France UMR7247, CNRS, Nouzilly, France Université François Rabelais de Tours, France Institut Français du Cheval et de l'Equitation, Nouzilly, France pmonget@tours.inra.fr.

Abstract

Free fatty acid receptors (FFAR) belong to a family of five G-protein coupled receptors that are involved in the regulation of lipid metabolism, so that their loss of function increases the risk of obesity. The aim of this study was to determine the expansion of genes encoding paralogs of FFAR2 in the chicken, considered as a model organism for developmental biology and biomedical research. By estimating the gene copy number using quantitative polymerase chain reaction, genomic DNA resequencing, and RNA sequencing data, we showed the existence of 23 ± 1.5 genes encoding FFAR2 paralogs in the chicken genome. The FFAR2 paralogs shared an identity from 87.2% up to 99%. Extensive gene conversion was responsible for this high degree of sequence similarities between these genes, and this concerned especially the four amino acids known to be critical for ligand binding. Moreover, elevated nonsynonymous/synonymous substitution ratios on some amino acids within or in close-vicinity of the ligand-binding groove suggest that positive selection may have reduced the effective rate of gene conversion in this region, thus contributing to diversify the function of some FFAR2 paralogs. All the FFAR2 paralogs were located on a microchromosome in a same linkage group. FFAR2 genes were expressed in different tissues and cells such as spleen, peripheral blood mononuclear cells, abdominal adipose tissue, intestine, and lung, with the highest rate of expression in testis. Further investigations are needed to determine whether these chicken-specific events along evolution are the consequence of domestication and may play a role in regulating lipid metabolism in this species.

KEYWORDS:

FFAR; chicken; duplication; evolution; gene conversion; positive selection

PMID:
25912043
PMCID:
PMC4453067
DOI:
10.1093/gbe/evv072
[Indexed for MEDLINE]
Free PMC Article

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