Regulation of FAT/CD36 mRNA gene expression by long chain fatty acids in the differentiated 3T3-L1 cells

Defects in fatty acid translocase (FAT/CD36) have been identified as a major factor in insulin resistance and defective fatty acid and glucose metabolism. Therefore, understanding of the regulation of FAT/CD36 expression and function is important for a potential therapeutic target for type II diabetes. We differentiated 3T3-L1 preadipocytes into matured adipocytes and examined the roles of insulin and long chain fatty acids on FAT/CD36 expression and function. Our results indicate that FAT/CD36 mRNA expression was not detected at preadipocyte but was significantly increased at matured adipocyte. In fully differentiated 3T3-L1 adipocytes, insulin significantly increased FAT/CD36 mRNA and protein expression in a dose dependent manner. The free fatty acid stearic acid reduced FAT/CD36 mRNA expression while the non-metabolizable free fatty acid alpha-bromopalmitate (2-BP) significantly increased FAT/CD36 mRNA and protein expression. Isoproterenol, in contrast, dose-dependently reduced FAT/CD36 mRNA expression and increased free fatty acid release. Mechanism analysis indicated that the effect of insulin and 2-BP on the FAT/CD36 mRNA gene expression may be mediated through activation of PPAR-γ, suggesting that FAT/CD36 may have important implications in the pathophysiology of defective fatty acid metabolism.