Carnitine palmitoyltransferase I gene in Synechogobius hasta: Cloning, mRNA expression and transcriptional regulation by insulin in vitro

Abstract

We cloned seven complete CPT I cDNA sequences (CPT I α1a-1a, CPT I α1a-1b, CPT I α1a-1c, CPT I α1a-2, CPT I α2a, CPT I α2b1a, CPT I β) and a partial cDNA sequence (CPT I α2b1b) from Synechogobius hasta. Phylogenetic analysis shows that there are four CPT I duplications in S. hasta, CPT I duplication resulting in CPT I α and CPT I β, CPT I α duplication producing CPT I α1 and CPT I α2, CPT I α2 duplication generating CPT I α2a and CPT I α2b, and CPT I α2b duplication creating CPT I α2b1a and CPT I α2b1b. Alternative splicing of CPT Iα1a results in the generation of four CPT I isoforms, CPT I α1a-1a, CPT I α1a-1b, CPT I α1a-1c and CPT I α1a-2. Five CPT I transcripts (CPT I α1a, CPT I α2a, CPT I α2b1a, CPT I α2b1b and CPT I β) mRNAs are expressed in a wide range of tissues, but their abundance of each CPT I mRNA shows the tissue-dependent expression patterns. Insulin incubation significantly reduces the mRNA expression of CPT Iα1a and CPT Iα2a, but not other transcripts in hepatocytes of S. hasta. For the first time, our study demonstrates CPT Iα2b duplication and CPT I α1a alternative splicing in fish at transcriptional level, and the CPT I mRNAs are differentially regulated by insulin in vitro, suggesting that four CPT I isoforms may play different physiological roles during insulin signaling.

Keywords: Carnitine palmitoyltransferase I; Insulin; Lipid metabolism; MRNA expression; Molecular clone; Synechogobius hasta.