C2C12 Myotubes in response to Palmitate

To identify mediators of obesity-linked reductions in PGC-1, we tested the effects of cellular nutrients in C2C12 myotubes. While overnight exposure to high insulin, glucose, glucosamine, or amino acids had no effect, saturated fatty acids (FA) potently reduced PGC-1a and b mRNA expression. Keywords: Nutrient Effect Cell culture - Mouse C2C12 myoblasts (ATCC, Manassas, VA) were maintained in Dulbecco’s modified Eagle’s medium (DMEM) supplemented with 20% fetal bovine serum (Invitrogen), at a confluency of 60-70%. To initiate differentiation, cells were allowed to reach 100% confluency and medium was changed to DMEM containing 2% horse serum (Invitrogen) and changed every 2 days. Full differentiation, with myotube fusion and spontaneous twitching, was observed at 5 days. Fatty acid stock preparation - Fatty acids were dissolved in 0.1 N sodium hydroxide (final concentration 100 mM) at 65°C for 2 hours and then complexed with 10% fatty acid-free BSA, yielding a final stock of 5 mM. Three replicates for each fatty-acid. Microarray analysis - RNA was isolated as described from C2C12 myotubes treated overnight with 500 µM palmitate or 1% BSA, and cRNA was synthesized. 10 mg of cRNA were hybridized to Affymetrix mouse 430A 2.0 arrays. Intensity values were quantified using MAS 5.0 software. MAPPFinder (www.genmapp.org) was used to integrate expression data with known pathways.