SREBF1 and fatty liver disease: ,108 SIRT1 is an essential metabolic/energy sensor that directly couples cellular metabolic/energy states (via intracellular NAD+/NADH ratios) to molecules involved in metabolic homeostasis, such as SREBP-1c and PPARα.109, 110, 111 SIRT1 deacetylates SREBP-1c, inhibiting lipogenesis and ameliorating hepatic steatosis.112