Upstream Stimulatory Factors 1 and 2 activate the human hepatic lipase promoter via E-box dependent and independent mechanisms.

Abstract We studied the transcriptional regulation of the HL gene by USF1and USF2in HepG2 cells. The transcriptional activity of the HL(− 685/+ 13) promoter construct was increased up to 25-fold by co-transfection with USF1and USF2. Silencing of USF1by RNA interference reduced promoter activityby 30–40%. Chromatin immunoprecipitationassays showed binding of endogenous USF1and USF2to the proximal HL promoter region. In gel shift assays, USF1and USF2bound to E-boxesat − 307/− 312 and − 510/− 516, and to the TATA-Inr region. Although the − 514C → T substitution abolished in vitro USF binding to the − 510/− 516 E-box, the increase in HL promoter activityby USF1and USF2was unaffected. Deletion and mutation analysis of the HL promoter region, and insertion of multiple E-boxcopies in front of a heterologous promoter, revealed that upregulation by USFs was mainly mediated through the − 307/− 312 E-boxand the TATA-Inr region. We conclude that in HepG2 cells USF1and USF2regulate transcriptional activity of the HL gene through their binding to the E-boxat − 307/− 312 and the TATA-Inr region.