Inhibition of acetyl‐CoA carboxylase activity prevents adipocyte differentiation in 3T3‐L1 cells

Abstract

Acetyl-CoA carboxylases (ACC) 1 and 2 catalyze the carboxylation of acetyl-CoA to malonyl-CoA and depend on biotin as a coenzyme. Cytoplasmic ACC1 produces malonyl-CoA which serves as a precursor in fatty acid (FA) synthesis. Malonyl-CoA produced by ACC2 in the outer mitochondrial membrane is an inhibitor of FA oxidation. We hypothesized that ACCs are checkpoints in adipocyte differentiation and tested this hypothesis in murine 3T3-L1 preadipocytes. Oil Red O staining and qRT-PCR were used to assess lipid droplet formation and the expression of adipocyte marker genes, respectively. Treatment of 3T3-L1 cells with up to 1 µM of the microbial ACC inhibitor soraphen A (SA) inhibited lipid droplet accumulation and was accompanied by a decrease in PPARγ mRNA expression (51.4±9.0% of controls, p<0.01) and a non-significant decrease in FABP4 mRNA expression to 55.1±21.6% of controls, at 4 days post differentiation. Treatment of 3T3-L1 cells with up to 200 μM palmitate maintained lipid droplet formation despite being treated with SA also. Expression of PPARy mRNA was similarly maintained in cells treated with both 100 nM SA and 200 µM palmitate (95.1±27.3% of controls). However, when SA treatment was initiated at 4 days post-differentiation of 3T3-L1 cells, the number or size of lipid droplets did not decrease. We conclude that ACCs are checkpoints in adipocyte differentiation. In future studies, we will use knockdown protocols to determine which of the two ACCs is the critical checkpoint in adipocyte differentiation. Supported by ARD Hatch, NIFA, and NIH.