Gene expression profiling in primary human skeletal myotubes with small molecule inhibitors of lipid accumulation

The development of insulin resistance is strongly associated with accumulation of intracellular lipid in tissues outside of adipose including skeletal muscle, liver and heart. In obese humans, intramyocellular lipid (IMCL) is negatively correlated with whole body insulin sensitivity. The skeletal myocyte imports fatty acids (FA) into the cell from circulating free fatty acids or lipoprotein particles such as VLDL, to support energy production. Once transported into the cell, FAs are oxidized for ATP production, used to build membranes, or stored as triglyceride. However, in the long term, increased delivery of fatty acids can exceed mitochondrial oxidative capacity and set the stage for a vicious cycle of cellular lipotoxicity. We have recently identified a novel small molecule inhibitor of lipid accumulation in skeletal mycytes termed SBI-477. Microarray transcriptomics was performed in primary human skeletal myotubes following oleate loading and treatment with SBI-477. This was also compared to A922500, a diacylglycerol transferase 1 (DGAT1) inhibitor. SBI-477 treatment reversed many of the transcriptomic effects of oleate loading in these cells but also produced a transcriptomic profile distinct from the DGAT1 inhibitor. Microarray expression profiling was performed with total RNA isolated from differentiated primary human skeletal myotubes. These cells were treated with BSA (control for oleate), 100micromolar oleic acid, oleate + 10micromolar SBI-477 and oleate + 1micromolar A922500 for 24 hours. Oleate and test compound were added at the same time to the cells. Two biologic replicates for each condition were included.