Fatty acids modulate porcine adipocyte differentiation and transcripts for transcription factors and adipocyte-characteristic proteins*

Porcine stromal-vascular cells (S/V cells) differentiate into adipocytes in vitro when presented with appropriate hormones and growth factors. Porcine S/V cells were differentiated in vitro in serum-free media with or without fatty acids to determine the effect of fatty acids on differentiation and on transcripts for peroxisome proliferator-activated receptor gamma (PPARgamma), CCAAT/enhancer binding protein alpha (C/EBPalpha), lipoprotein lipase (LPL) and adipocyte fatty acid binding protein (aP2). Differentiation was measured by Oil Red O staining and transcript concentrations were measured by Northern analysis using porcine riboprobes. Addition of 100 µM oleic acid (C18:1) for 5 days increased differentiation and the mRNA levels for PPARgamma, C/EBPalpha, LPL and aP2. Other medium- and long-chain fatty acids were less active. Adipocyte differentiation and transcript concentrations for PPARgamma, C/EBPalpha, LPL and aP2 were increased by C18:1 in a dose-related manner. Differentiation was greater at 10 days than at 5 days than at 1 day, and C18:1 increased differentiation at each time. Transcript concentrations were increased by C18:1 at 1 and 5 days, but not at 10 days. These results suggest that the main effect of C18:1 is on regulating gene expression (an acute or drug-like effect) rather than changing the membrane fluidity as a result of changing membrane fatty acid composition (a chronic or nutrient-like effect). Taken together, these results indicate that selected fatty acids modulate porcine adipocyte differentiation and transcripts for adipocyte differentiation-related proteins such as PPARgamma, C/EBPalpha, LPL and aP2.