Fatty acids activate transcription of the muscle carnitine palmitoyltransferase I gene in cardiac myocytes via the peroxisome proliferator-activated receptor alpha.
To explore the gene regulatory mechanisms involved in the metabolic control of cardiac fatty acid oxidative flux, the expression of muscle-type carnitine palmitoyltransferase I (M-CPT I) was characterized in primary cardiac myocytes in culture following exposure to the long-chain mono-unsaturated fatty acid, oleate. Oleate induced steady-state levels of M-CPT I mRNA 4.5-fold. The transcription of a plasmid construct containing the human M-CPT I gene promoter region fused to a luciferase gene reporter transfected into cardiac myocytes, was induced over 20-fold by long-chain fatty acid in a concentration-dependent and fatty acyl-chain length-specific manner. The M-CPT I gene promoter fatty acid response element (FARE-1) was localized to a hexameric repeat sequence located between 775 and 763 base pairs upstream of the initiator codon. Cotransfection experiments with expression vectors for the peroxisome proliferator-activated receptor alpha (PPARalpha) demonstrated that FARE-1 is a PPARalpha response element capable of conferring oleate-mediated transcriptional activation to homologous or heterologous promoters. Electrophoretic mobility shift assays demonstrated that PPARalpha bound FARE-1 with the retinoid X receptor alpha. The expression of M-CPT I in hearts of mice null for PPARalpha was approximately 50% lower than levels in wild-type controls. Moreover, a PPARalpha activator did not induce cardiac expression of the M-CPT I gene in the PPARalpha null mice. These results demonstrate that long-chain fatty acids regulate the transcription of a gene encoding a pivotal enzyme in the mitochondrial fatty acid uptake pathway in cardiac myocytes and define a role for PPARalpha in the control of myocardial lipid metabolism.
Brandt
J M
JM
Center for Cardiovascular Research, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Djouadi
F
F
Kelly
D P
DP
D000818:Animals; D000831:Animals, Newborn; D001483:Base Sequence; D002334:Carnitine O-Palmitoyltransferase / Q000096:biosynthesis / Q000235:genetics*; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004852:Epoxy Compounds / Q000494:pharmacology; D005230:Fatty Acids, Nonesterified / Q000494:pharmacology*; D017930:Genes, Reporter; D006801:Humans; D008156:Luciferases / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D018482:Muscle, Skeletal / Q000201:enzymology*; D009206:Myocardium / Q000201:enzymology*; D019301:Oleic Acid / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D012091:Repetitive Sequences, Nucleic Acid; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects*; D015533:Transcriptional Activation / Q000187:drug effects*; D014162:Transfection
D004852:Epoxy Compounds; D005230:Fatty Acids, Nonesterified; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D019301:Oleic Acid; D008156:Luciferases; D002334:Carnitine O-Palmitoyltransferase; C054207:etomoxir