Reactive oxygen species mediate angiotensin II-induced transcytosis of low-density lipoprotein across endothelial cells.
Reactive oxygen species mediate angiotensin II-induced transcytosis of low-density lipoprotein across endothelial cells.
复制标题
活性氧介导血管紧张素 II 诱导的低密度脂蛋白跨内皮细胞的转胞吞作用。
DOI：
10.3892/ijmm.2017.2887
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发表时间：
2017-03
影响因子：
5.4
通讯作者：
Jin S
中科院分区：
文献类型：
--
作者：
Bian F;Cui J;Zheng T;Jin S
血浆低密度脂蛋白（LDL）颗粒通过跨内皮的胞吞作用滞留于内皮下空间是动脉粥样硬化（AS）的起始步骤。血管紧张素II（AngII）作为肾素-血管紧张素系统（RAS）的主要效应分子，参与了AS发生发展的几个重要步骤。然而，血管紧张素II是否可以直接发挥促动脉粥样硬化的作用，促进低密度脂蛋白跨内皮屏障的转胞吞作用，尚未确定。本研究通过测定2′，7 ′-二氯荧光素（DCF-DA）的荧光强度，发现血管紧张素Ⅱ（Ang Ⅱ）可上调内皮细胞内活性氧（ROS）水平。基于我们的转胞吞模型，我们观察到Ang II显著促进LDL转胞吞，而转胞吞抑制剂甲基-β-环糊精（MβCD）和ROS抑制剂二硫苏糖醇（DTT）显著阻断Ang II刺激的LDL转胞吞增加。共聚焦成像分析显示，Ang Ⅱ作用后细胞对LDL的摄取和LDL在脐静脉壁的滞留均显著增加，而MβCD和DTT则显著抑制Ang Ⅱ的作用。此外，参与小窝介导的转胞吞的蛋白质，包括LDL受体（LDLR）、小窝蛋白-1和cavin-1，与Ang II诱导的LDL跨EC的转胞吞相关。然而，在我们的研究中，这个过程是独立的网格蛋白。值得注意的是，ROS抑制剂DTT显著降低了这些蛋白质的表达水平。因此，ROS是血管紧张素II诱导的LDL转胞吞作用的关键介质。希望这些发现将为血脂异常和RAS在动脉粥样硬化形成中的相互作用提供新的见解。
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.