cDNA cloning and expression analysis of canine uncoupling protein 2 and 3 genes

Abstract

The uncoupling proteins (UCPs) play an important role in energy homeostasis. To date, five UCP homologs, UCP1 to UCP5, have been identified in mammals. Both UCP2 and UCP3 have been found to decrease membrane potential and increase thermogenesis. They are regarded as inducers of obesity and type 2 diabetes in humans. We showed that the dog UCP2 and UCP3 cDNAs consisted of a part of the 5'-UTR sequence and a complete open reading frame in each gene. Comparisons with the gene structure in humans, dog genome sequences, and the transcripts in this study showed that dog UCP2 consists of exons 1 to 8 and dog UCP3 consists of exons 1 to 7. In dog UCP 3, exon 3-skipped transcripts were also observed. A UCP2 and UCP3 gene expression study using reverse transcription-polymerase chain reaction and 27 kinds of total RNA from dog tissues showed that tissue distribution of gene expression was different between dog UCP2 and UCP3. The present data may provide us with information regarding DNA polymorphism and help in further investigations of the influence of UCP2 and UCP3 activity on canine energy balance.