Nampt (Visfatin/PBEF)

Nicotinamide phosphoribosyltransferase (Nampt) is the rate limiting enzyme in the conversion of nicotinamide to nicotinamide adenine dinucleotide (NAD), a classic coenzyme of cellular redox reactions. Nampt was originally identifi ed as a presumptive cytokine for B cell maturation and named Pre-B cell colony enhancing factor (PBEF). Recently, Nampt was discovered to be a visceral fat-derived adipokine and also named Visfatin. Fukuhara et al. showed that Nampt (Visfatin/PBEF) exerts insulin-mimetic effects in animal models, stimulates glucose uptake into muscle cells and adipocytes, suppresses glucose release from hepatocyte, and binds the insulin receptor. These observations draw much attention but subsequent studies reported confl icting results regarding its relation with adiposity, with subcutaneous or visceral fat and with insulin resistance. Others could not repeat the insulin-mimetic effects and the Fukuhara work was subsequently retracted. Interestingly, while the insulin-mimetic effect is unclear secreted Nampt (Visfatin/PBEF) has recently been shown to regulate insulin secretion in β cells. Nampt (Visfatin/PBEF) has also been shown to be a cell survival factor and to be involved in subclinical infl ammation.