REGULATION OF THE HUMAN LONG-CHAIN ACYL-COA DEHYDROGENASE GENE BY NUCLEAR HORMONE-RECEPTOR TRANSCRIPTION FACTORS

Mitochondrial fatty acid oxidation provides most of the energy require d for myocardial function after birth. Long chain acyl-CoA dehydrogena se (LCAD) catalyzes the first step in the beta-oxidation spiral. Our o bjective was to define regulatory elements of the human LCAD gene requ ired for high levels of expression in mature heart and to locate eleme nts suppressing gene expression in the fetus. We characterized the hum an LCAD gene structure and used in vitro transfection into cardiomyocy tes and hepatoma cells of LCAD genomic fragments fused to a reporter g ene to examine the effects of putative regulatory elements on transcri ption. Binding of transcription factors to nuclear hormone receptor co nsensus DNA binding domains was studied by gel shift experiments. The 200 bp of the human LCAD gene immediately upstream of the transcriptio n initiation site are sufficient to act as a minimal promoter for the gene and provide some tissue-specific positive regulatory elements. Th e region from -1800 bp to -250 bp contains elements which markedly sup press transcription, including nuclear hormone receptor response eleme nts. The dominant interaction is with the repressor factor, chicken ov albumin upstream promoter transcription factor. We conclude that the d evelopmental and tissue-specific regulation of the human LCAD gene is mediated, in part, by these nuclear hormone receptor transcription fac tors.