Molecular dissection of angiotensin II-activated human LOX-1 promoter

Objective - LOX-1, a receptor for oxidized low-density lipoprotein, plays a critical role in atherosclerosis. Its expression is upregulated by pro-atherogenic stimuli, such as angiotensin II (Ang II). In this study, we explored LOX-1 transcriptional promoter activation in response to Ang II in human coronary artery endothelial cells (HCAECs). Methods and Results - We constructed full-length and deletion LOX-1 promoter mutants and examined their activation in response to Ang II in HCAECs. The Ang II ( 1 mu mol/L for 24 hours) markedly induced LOX-1 promoter activity beyond the basal level, and a 116-bp fragment ( between nt - 2247 and - 2131) was necessary for this induction. Within this 116-bp promoter fragment, there is a potential binding motif for transcription factor NF-kappa B. By EMSA, we observed the activation of NF-kappa B by Ang II. The critical role of NF-kappa B in Ang II - induced LOX-1 promoter activation was confirmed by mutagenesis assay, and further confirmed by blocking NF-kappa B activation with the NF-kappa B inhibitor caffeic acid phenethyl ester or NF-kappa B p65 siRNA. Conclusion - This study strongly suggests that Ang II, by activating NF-kappa B, induces LOX-1 promoter activation.