title: Dual modulation of both lipid oxidation and synthesis by peroxisome proliferator-activated receptor-gamma coactivator-1alpha and -1beta in cultured myotubes.
abstract: The peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1) family is a key regulator of mitochondrial function, and reduced mRNA expression may contribute to muscle lipid accumulation in obesity and type 2 diabetes. To characterize the effects of PGC-1 on lipid metabolism, we overexpressed PGC-1alpha and PGC-1beta in C2C12 myotubes using adenoviral vectors. Both PGC-1alpha and -1beta increased palmitate oxidation [31% (P<0.01) and 26% (P<0.05), respectively] despite reductions in cellular uptake [by 6% (P<0.05) and 21% (P<0.001)]. Moreover, PGC-1alpha and -1beta increased mRNA expression of genes regulating both lipid oxidation (e.g., CPT1b and ACADL/M) and synthesis (FAS, CS, ACC1/2, and DGAT1). To determine the net effect, we assessed lipid composition in PGC-1-expressing cells. Total lipid content decreased by 42% in palmitate-loaded serum-starved cells overexpressing PGC-1alpha (P<0.05). In contrast, in serum-replete cells, total lipid content was not significantly altered, but fatty acids C14:0, C16:0, C18:0, and C18:1 were increased 2- to 4-fold for PGC-1alpha/beta (P<0.05). Stable isotope-based dynamic metabolic profiling in serum-replete cells labeled with (13)C substrates revealed both increased de novo fatty acid synthesis from glucose and increased fatty acid synthesis by chain elongation with either PGC-1alpha or -1beta expression. These results indicate that PGC-1 can promote both lipid oxidation and synthesis, with net balance determined by the nutrient/hormonal environment.-Espinoza, D. O., Boros, L. G., Crunkhorn, S., Gami, H., Patti, M.-E. Dual Modulation of both lipid oxidation and synthesis by peroxisome proliferator-activated receptor-gamma coactivator-1alpha and -1beta in cultured myotubes.
authors.affiliation: Research Division, Joslin Diabetes Center, Boston, Massachusetts, USA.
authors.forename: Daniel O
authors.initials: DO
authors.lastname: Espinoza
authors.forename: Laszlo G
authors.initials: LG
authors.lastname: Boros
authors.forename: Sarah
authors.initials: S
authors.lastname: Crunkhorn
authors.forename: Hiral
authors.initials: H
authors.lastname: Gami
authors.forename: Mary-Elizabeth
authors.initials: ME
authors.lastname: Patti
mesh_terms: D000818:Animals; D002460:Cell Line; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D009765:Obesity / Q000235:genetics / Q000378:metabolism; D010084:Oxidation-Reduction; D010168:Palmitates / Q000378:metabolism*; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors
chemical_list: D010168:Palmitates; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C485290:Ppargc1a protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors