Insulin- and polyunsaturated fatty acid-responsive region(s) of rat ATP citrate-lyase gene promoter

Abstract

To investigate the regulatory DNA sequences required for insulin-stimulation of the ATP citrate-lyase (ACL) gene as well as for polyunsaturated fatty acid (PUFA)-suppression of this gene, primary cultured hepatocytes were transfected with plasmids containing the 5′-flanking sequence of the rat ACL gene fused to the chloramphenicol acetyltransferase (CAT) gene. Sequences from −861, −194 or −104 to +128 of the ACL gene directed an increase in CAT activity in hepatocytes when insulin was added to the medium containing either glucose or pyruvate. The CAT activities stimulated by insulin were reduced by the addition of PUFA, in accordance with the responses on the endogenous ACL gene expression. Further deletion to −20, however, resulted in loss of the responses. The results suggest that the region from −104 to −20 of the ACL gene is responsible for regulation due to insulin and PUFAs. In particular, the region from −61 to −49 of the ACL has sequence similarity to the insulin-responsive regions of fatty acid synthase and acetyl-CoA carboxylase.