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).


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 micromol/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-kappaB. By EMSA, we observed the activation of NF-kappaB by Ang II. The critical role of NF-kappaB in Ang II-induced LOX-1 promoter activation was confirmed by mutagenesis assay, and further confirmed by blocking NF-kappaB activation with the NF-kappaB inhibitor caffeic acid phenethyl ester or NF-kappaB p65 siRNA.


CONCLUSIONS
This study strongly suggests that Ang II, by activating NF-kappaB, induces LOX-1 promoter activation.
Department of Internal Medicine, University of Arkansas for Medical Sciences, Central Arkansas Veterans Healthcare System, Little Rock, Arkansas, USA.
Jiawei
J
Chen
Yong
Y
Liu
Hongmei
H
Liu
Paul L
PL
Hermonat
Jawahar L
JL
Mehta
D000804:Angiotensin II / Q000494:pharmacology*; D001665:Binding Sites; D002478:Cells, Cultured; D024202:Electrophoretic Mobility Shift Assay; D042783:Endothelial Cells / Q000378:metabolism; D006801:Humans; D016328:NF-kappa B / Q000502:physiology; D011401:Promoter Regions, Genetic; D051127:Scavenger Receptors, Class E / Q000235:genetics*
D016328:NF-kappa B; C495137:OLR1 protein, human; D051127:Scavenger Receptors, Class E; D000804:Angiotensin II