Fig. 2.

Transcriptional control of hepatic lipogenesis. SREBP-2 is activated when cellular sterol levels are low, and controls the expression of genes involved in sterol biosynthesis. SREBP-1c and ChREBP are activated by insulin and glucose, respectively. Ingestion of carbohydrates increases circulating glucose and insulin levels, by inducing insulin production from pancreatic β cells. SREBP-1c and ChREBP bind to specific promoter elements to activate the transcription of genes in glycolytic and lipogenic pathways. XBP1 is required for the de novo synthesis of sterols and fatty acids in the liver and is activated in the presence of high glucose. The mechanism by which XBP1 controls sterol and fatty acid synthesis genes remains to be further investigated