Nicotinamide N-methyltransferase (NNMT) regulates insulin sensitivity differentially in white and brown adipocytes

Background: Nicotinamide N-methyltransferase (NNMT) is a novel regulator of energy homeostasis in adipose tissue. NNMT expression is increased in obesity. NNMT knockdown prevents from obesity. Mice lacking glucose transporter 4 (Glut4) in adipose tissue are insulin resistant and overexpress NNMT in fat. Fat-specific Glut4 transgenic mice are insulin hypersensitive and have low NNMT expression. Aim: In the present study we investigate if NNMT activity regulates insulin sensitivity in cultured white (3T3-L1) and immortalized brown adipocytes. Methods: We developed non-radioactive, microtiter-plate NNMT activity an…