Description
Nicotinamide phosphoribosyltransferase (Nampt; pre-B cell colony-enhancing factor; PBEF; Visfatin) is an 52kDa adipokine secreted by adipose tissue and involved in the biosynthesis of nicotinamide adenine dinucleotide (NAD+). Two forms of Nampt exist, an intracellular form (iNampt) and an extracellular form (eNampt). While the function of iNampt as an essential and rate-limiting NAD+ biosynthetic enzyme is well established, the physiological role of eNampt is still a matter of debate. Nampt has various functions, including the promotion of vascular smooth muscle cell maturation and inhibition of neutrophil apoptosis. It activates insulin receptor and has insulin-mimetic effects, lowering blood glucose and improving insulin sensitivity. The protein is highly expressed in visceral fat and serum levels of the protein correlate with obesity