Genomic structure and expression of uncoupling protein 2 genes in rainbow trout (Oncorhynchus mykiss).
BACKGROUND
Uncoupling protein 2 (UCP2) belongs to the superfamily of mitochondrial anion carriers that dissociate the respiratory chain from ATP synthesis. It has been determined that UCP2 plays a role in several physiological processes such as energy expenditure, body weight control and fatty acid metabolism in several vertebrate species. We report the first characterization of UCP2s in rainbow trout (Oncorhynchus mykiss).


RESULTS
Two UCP2 genes were identified in the rainbow trout genome, UCP2A and UCP2B. These genes are 93% similar in their predicted amino acid sequences and display the same genomic structure as other vertebrates (8 exons and 7 introns) spanning 4.2 kb and 3.2 kb, respectively. UCP2A and UCP2B were widely expressed in all tissues of the study with a predominant level in macrophage-rich tissues and reproductive organs. In fry muscle we observed an increase in UCP2B expression in response to fasting and a decrease after refeeding in agreement with previous studies in human, mouse, rat, and marsupials. The converse expression pattern was observed for UCP2A mRNA which decreased during fasting, suggesting different metabolic roles for UCP2A and UCP2B in rainbow trout muscle. Phylogenetic analysis including other genes from the UCP core family located rainbow trout UCP2A and UCP2B with their orthologs and suggested an early divergence of vertebrate UCPs from a common ancestor gene.


CONCLUSIONS
We characterized two UCP2 genes in rainbow trout with similar genomic structures, amino acid sequences and distribution profiles. These genes appeared to be differentially regulated in response to fasting and refeeding in fry muscle. The genomic organization and phylogeny analysis support the hypothesis of a common ancestry between the vertebrate UCPs.
Coulibaly
Issa
I
West Virginia University, Animal and Veterinary Sciences Division, Po Box 6108, Morgantown, WV 26506, USA. icoulibaly@ncccwa.ars.usda.gov
Gahr
Scott A
SA
Palti
Yniv
Y
Yao
Jianbo
J
Rexroad
Caird E
CE
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002347:Carps / Q000235:genetics / Q000378:metabolism; D018076:DNA, Complementary / Q000032:analysis; D005215:Fasting / Q000378:metabolism; D005260:Female; D020869:Gene Expression Profiling; D040342:Genetic Structures; D006801:Humans; D007473:Ion Channels / Q000235:genetics* / Q000378:metabolism; D008297:Male; D051379:Mice; D024101:Mitochondrial Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D017686:Oncorhynchus mykiss / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D051381:Rats; D050436:Regulatory Elements, Transcriptional; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution; D014157:Transcription Factors / Q000378:metabolism; D000071246:Uncoupling Protein 2; D015027:Zebrafish / Q000235:genetics / Q000378:metabolism
D018076:DNA, Complementary; D007473:Ion Channels; D024101:Mitochondrial Proteins; D020033:Protein Isoforms; D014157:Transcription Factors; C000604389:UCP2 protein, human; C000604390:Ucp2 protein, mouse; C000604391:Ucp2 protein, rat; D000071246:Uncoupling Protein 2