title: Reactive oxygen species mediate angiotensin II-induced transcytosis of low-density lipoprotein across endothelial cells.
abstract: The retention of plasma low-density lipoprotein (LDL) particles to subendothelial spaces through transcytosis across the endothelium is the initial step of atherosclerosis (AS). Angiotensin II (Ang II), as the principal effector molecule of the renin-angiotensin system (RAS), is implicated in several important steps of AS development. However, whether or not Ang II can directly exert a pro‑atherogenic effect by promoting LDL transcytosis across endothelial barriers, has not been defined. In the present study, we found that Ang II upregulated intracellular reactive oxygen species (ROS) levels in endothelial cells (ECs) by measuring fluorescence of 2',7'-dichlorofluorescein (DCF‑DA). Based on our transcytosis model, we observed that Ang II significantly accelerated LDL transcytosis, whereas transcytosis inhibitor methyl-β-cyclodextrin (MβCD) and ROS inhibitor dithiothreitol (DTT), markedly blocked the Ang II-stimulated increase in LDL transcytosis. Confocal imaging analysis revealed that both LDL uptake by cells and LDL retention in human umbilical venous walls were highly elevated after Ang II exposure, while MβCD and DTT significantly inhibited the effects of Ang II. What is more, proteins involved in caveolae-mediated transcytosis, including LDL receptor (LDLR), caveolin-1 and cavin-1, were associated with Ang II-induced LDL transcytosis across the ECs. Nevertheless, this process was independent of clathrin in our study. Of note, ROS inhibitor, DTT, markedly decreased the expression levels of those proteins. Consequently, ROS are critical mediators in Ang II-induced LDL transcytosis. Hopefully, these findings will provide novel insight into the crosstalk between dyslipidemia and RAS in atherogenesis.
authors.affiliation: Department of Pharmacy, The Affiliated Hospital of Xiangyang Central Hospital of Hubei University of Arts and Science, Xiangyang, Hubei 441000, P.R. China.
authors.forename: Fang
authors.initials: F
authors.lastname: Bian
authors.affiliation: Department of Cardiothoracic Surgery, The Affiliated Hospital of Xiangyang Central Hospital of Hubei University of Arts and Science, Xiangyang, Hubei 441000, P.R. China.
authors.forename: Jun
authors.initials: J
authors.lastname: Cui
authors.affiliation: Department of Endocrinology, Institute of Geriatric Medicine, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China.
authors.forename: Tao
authors.initials: T
authors.lastname: Zheng
authors.affiliation: Department of Endocrinology, Institute of Geriatric Medicine, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China.
authors.forename: Si
authors.initials: S
authors.lastname: Jin
mesh_terms: D000804:Angiotensin II / Q000378:metabolism* / Q000494:pharmacology; D042783:Endothelial Cells / Q000378:metabolism*; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D057900:Transcytosis / Q000187:drug effects
chemical_list: D008077:Lipoproteins, LDL; D017382:Reactive Oxygen Species; D000804:Angiotensin II