Fig. 6.

Mechanisms of NAMPT protecting liver from high fat diet-induced hepatic steatosis. NAMPT promotes the production of NAD⁺ by activating the NAD⁺ salvage pathway and in turn, the increased NAD⁺ as a substrate activates Sirt1 signaling pathways, alleviating high fat diet-induced hepatic steatosis in mice. On the one hand, the activation of Sirt1 promotes the deacetylation of SREBP1 in which the inhibition of SREBP1 activity finally results in inhibitions of the expressions of lipogenesis genes including FASN and ACC. On the other hand, Sirt1 directly activates AMPKα which further inhibits SREBP1 activities