Characterization of the human very-long-chain acyl-CoA dehydrogenase gene promoter region: A role for activator protein 2

Very-long-chain acyl-CoA dehydrogenase (VLCAD) is one of a family of nuclea r-encoded enzymes that catalyze the initial step in mitochondrial fatty aci d beta-oxidation (FAO), Previous studies have indicated that two other memb ers of the AD gene family (medium-chain AD and long-chain AD) are controlle d at the transcriptional level by nuclear hormone receptors. in this study, we have cloned and characterized the human VLCAD gene promoter region to i dentify cis-acting elements involved in its transcriptional control, VLCAD gene promoter-luciferase reporter (VLCAD-Luc) constructs were found to be t ranscriptionally active in a variety of mammalian cell lines and in primary rat cardiomyocytes when driven by varying lengths of the VLCAD promoter re gion. Removal of a 20-bp DNA segment of the proximal VLCAD gene promoter ma rkedly reduced the transcriptional activity of VLCAD-Luc constructs. Gel mo bility shift assays identified a DNA-binding activity in nuclear extracts p repared from human hepatoma G2 cells that interacted with the 20-bp regulat ory region. Competition studies revealed that this DNA-binding activity cou ld be abolished by a molar excess of unlabeled specific oligonucleotide as well as a DNA fragment containing an activator protein 2 (AP-a)-binding sit e but not by an unrelated nonspecific DNA fragment. These results provide a n initial characterization of the human VLCAD gene promoter, identify AP-2 as a candidate activator of VLCAD gene transcription, and suggest that VLCA D gene transcription may be regulated by pathways distinct from that of oth er AD genes, (C) 1999 Academic Press.