Glucose Utilization, Lipid Metabolism and BMP-Smad Signaling Pathway of Porcine Intramuscular Preadipocytes Compared with Subcutaneous Preadipocytes

BACKGROUND/AIMS: We previously reported that porcine intramuscular (i.m.) preadipocytes were different from subcutaneous (s.c.) preadipocytes on cell differentiation and lipid accumulation, but the underlying mechanisms remained unknown. The paper aims to investigate the underlying mechanisms by comparing the differences between i.m. and s.c. preadipocytes in glucose utilization, lipid metabolism, and the role of BMP signaling pathway. METHODS: Experiments were performed in porcine primary i.m. and s.c. preadipocytes in culture. The mRNA and protein expression patterns were determined respectively by Quantitative real-time PCR and Western blot. Cytosolic triglycerides were examined by triglyceride assay. RESULTS: The i.m. preadipocytes consumed more glucose by expression of GLUT1 and s.c. preadipocytes mainly utilized exogenic fatty acids for lipid synthesis by expression of LPL and FAT. Meanwhile, the expression of genes related to lipogenesis and lipolysis in s.c. preadipocytes increased more quickly than those in i.m. preadipocytes. The expression patterns of the genes involved in BMP-Smad signaling pathway were consistent with those of the genes participated in adipocytes differentiation in both i.m. and s.c. preadipocytes. Exogenous BMP2 significantly increased, whereas Noggin and Compound C, remarkably decreased the triglycerides content in i.m. preadipocytes, without affecting s.c. preadipocytes. BMP2 shRNA significantly reduced the mRNA levels of the downstream genes of BMP-Smad signaling pathway and PPARγ in both i.m. and s.c. preadipocytes. CONCLUSION: These findings suggested that the differentiation and lipid accumulation differences between i.m. and s.c. preadipocytes might be caused by the different manners of glucose utilization, lipid metabolism and the BMP-Smad signaling pathway. The special feature of i.m. adipocytes implied that these cells might be a potential target for treatment of diabetes.