title: Regulation of carnitine palmitoyltransferase I (CPT-Ialpha) gene expression by the peroxisome proliferator activated receptor gamma coactivator (PGC-1) isoforms.
abstract: The peroxisome proliferator activated receptor gamma coactivators (PGC-1) have important roles in mitochondrial biogenesis and metabolic control in a variety of tissues. There are multiple isoforms of PGC-1 including PGC-1alpha and PGC-1beta. Both the PGC-1alpha and beta isoforms promote mitochondrial biogenesis and fatty acid oxidation, but only PGC-1alpha stimulates gluconeogenesis in the liver. Carnitine palmitoyltransferase I (CPT-I) is a key enzyme regulating mitochondrial fatty acid oxidation. In these studies, we determined that PGC-1beta stimulated expression of the "liver" isoform of CPT-I (CPT-Ialpha) but that PGC-1beta did not induce pyruvate dehydrogenase kinase 4 (PDK4) which is a regulator of pyruvate metabolism. The CPT-Ialpha gene is induced by thyroid hormone. We found that T3 increased the expression of PGC-1beta and that PGC-1beta enhanced the T3 induction of CPT-Ialpha. The thyroid hormone receptor interacts with PGC-1beta in a ligand dependent manner. Unlike PGC-1alpha, the interaction of PGC-1beta and the T3 receptor does not occur exclusively through the leucine-X-X-leucine-leucine motif in PGC-1beta. We have found that PGC-1beta is associated with the CPT-Ialpha gene in vivo. Overall, our results demonstrate that PGC-1beta is a coactivator in the T3 induction of CPT-Ialpha and that PGC-1beta has similarities and differences with the PGC-1alpha isoform.
authors.affiliation: Department of Pharmacology, College of Medicine, University of Tennessee Health Science Center, 874 Union Avenue, Memphis, TN 38163, USA.
authors.forename: Prabodh
authors.initials: P
authors.lastname: Sadana
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Shulan
authors.initials: S
authors.lastname: Song
authors.forename: George A
authors.initials: GA
authors.lastname: Cook
authors.forename: Marshall B
authors.initials: MB
authors.lastname: Elam
authors.forename: Edwards A
authors.initials: EA
authors.lastname: Park
mesh_terms: D000818:Animals; D002334:Carnitine O-Palmitoyltransferase / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D022781:Hepatocytes / Q000187:drug effects / Q000201:enzymology; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D037042:Thyroid Hormone Receptors beta / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014284:Triiodothyronine / Q000494:pharmacology
chemical_list: D020033:Protein Isoforms; D012333:RNA, Messenger; D037042:Thyroid Hormone Receptors beta; D014157:Transcription Factors; C111264:peroxisome-proliferator-activated receptor-gamma coactivator-1; D014284:Triiodothyronine; D008156:Luciferases; D002334:Carnitine O-Palmitoyltransferase