Sterol regulatory element-binding protein-1 as a dominant transcription factor for gene regulation of lipogenic enzymes in the liver.

Sterol regulatory element-binding proteins (SREBPs) are basic helix-loop-helix (bHLH) type transcription factors that control expression of genes involved in biosynthesis of cholesterol and fatty acids. Dietary studies with normal, transgenic, and knockout mice have established SREBP-1 as a dominant transcription factor regulating gene expression of lipogenic enzyme in the liver. Polyunsaturated fatty acids inhibit hepatic lipogenic enzymes through suppressing SREBP-1. Whereas SREBP-2 exerts sterol regulation through cleavage of the membrane-bound precursor protein to liberate the active nuclear form into the nucleus, SREBP-1 controls lipogenic enzymes by self-regulating its own transcription level. Promoter analysis of the SREBP-1 gene will be important to clarify the mechanism of nutritional regulation of lipogenic genes.