Fig. 4.
PGC-1α overexpression increases both palmitic acid and lignoceric acid oxidation in human primary myotubes. Fatty acid oxidation (FAO) with radiolabeled substrates was performed by using primary myotubes homogenates. A: [1-14C]palmitate oxidation and acid-soluble metabolites (ASM). B: palmitate oxidation efficiency was expressed by an index of complete oxidation/acid-soluble metabolites (CO2/ASM); an increase in the index of CO2/ASM in the Ad-PGC-1α group indicates that oxidation efficiency is elevated post-PGC-1α overexpression. C: [1-14C]lignoceric acid (C24:0). VLCFA, which is necessarily oxidized first by peroxisomes, was used to assess mitochondrial oxidation, which utilized peroxisomal-derived fatty acid metabolites to boost mitochondrial/peroxisomal fatty acid disposal. D: lignoceric acid oxidation efficiency. E: indirect measure of total triglyceride (IMTG) content by measurement of triacylglycerol (TAG) content in cell lysates. F: lipid droplet metabolism and ether phospholipid synthesis gene expression by real-time qRT-PCR. mRNA expression was determined using the comparative CT method (ΔΔCT) with an endogenous control (18S ribosomal RNA) for normalization and then compared with the Ad-GFP group. Results are shown as means ± SE (n = 6). *P < 0.05, **P < 0.005, and ***P < 0.001 vs. Ad-GFP groups by paired, 2-tailed t-test. DGAT1, diacylglycerol acyltransferase 1 responsible for TAG synthesis (ΔΔCT value: −2.48); ATGL, adipose triglyceride lipase (ΔΔCT value: −1.54); PLIN5, perilipin 5 involved in lipid droplet mobilization (ΔΔCT value: −4.04); GNPAT/DHAPAT, glyceronephosphate acyltransferase-dihydroxyacetone phosphate acyltransferase involved in ether phospholipid synthesis (ΔΔCT value: −0.46) vs. Ad-GFP groups by paired 2-tailed t-test.