ABSTRACT
Type 2 diabetes results from two defects, insulin resistance and beta cell dysfunction. At the molecular and cellular levels, there is a connection between fatty acid accumulation and insulin resistance in muscles. Although several mechanisms involved in FFA-induced muscle insulin resistance, the exact mechanism is poorly understood. Recent studies show that the defect in insulin signaling pathway might be underlying mechanism for FFA-induced insulin resistance in the muscle. Protein tyrosine phosphatases like Leukocyte common antigen-related [LAR] are the key elements of insulin signaling and they can be a candidate in FFA induced insulin resistance. Studies have shown that type 2 diabetes involved and obese individuals have had increased levels of LAR in their tissues. However, the responsible factor for LAR overexpression is not well understood. In this study we investigate ceramide effect on LAR expression in the muscle cells. In this laboratory study C2C12 cells [mouse skeletal] after differentiation to myotubes using 2% of horse serum for 4 days, treated with 50 and 100 mMs of C2ceramide for 16h. RNA extracted, cDNA synthesized and Real Time PCR using specific primers for LAR and beta actin used. To detect LAR protein levels western blot was used. 100 mMs Ceramide [45%, P<0.01] significantly induced LAR mRNA expression but there was not significant difference between 50mM ceramide and untreated cells. The results from real time confirmed by protein data. 100 mMs Ceramide [52%, P<0.01] significantly induced LAR protein levels in comparison of control. The data from this study provide evidence that ceramide around pathologic concentration induce LAR expression. Results supported by human studies that were showed that diabetic and obese persons have a high level of LAR expression and revealed ceramide can be one of the responsible factors for inducing LAR expression in diabetic patients. However, further investigations are needed to clarify exact role of LAR in FFA induced insulin resistance.