Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.
J Cereb Blood Flow Metab. 2011 Mar;31(3):842-54. doi: 10.1038/jcbfm.2010.180. Epub 2010 Oct 13.
Cerebrovascular endothelial cells (CECs) are crucial components of the blood-brain barrier. Our previous study showed that oxidized low-density lipoprotein (oxLDL) induces apoptosis of CECs. This study was designed to further evaluate the effects of resveratrol on oxLDL-induced CEC insults and its possible molecular mechanisms. Resveratrol decreased the oxidation of LDL into oxLDL. Additionally, the oxLDL-caused oxidative stress and cell damage were attenuated by resveratrol. Exposure of CECs to oxLDL induced cell shrinkage, DNA fragmentation, and cell apoptosis, but resveratrol defended against such injuries. Application of Lox-1 small interference (si)RNA into CECs reduced the translation of this membrane receptor, and simultaneously increased resveratrol protection from oxLDL-induced cell apoptosis. By comparison, overexpression of Lox-1 attenuated resveratrol protection. Resveratrol inhibited oxLDL-induced Lox-1 mRNA and protein expressions. Both resveratrol and Lox-1 siRNA decreased oxLDL-enhanced translocation of proapoptotic Bcl-2-associated X protein (Bax) from the cytoplasm to mitochondria. Sequentially, oxLDL-induced alterations in the mitochondrial membrane potential, cytochrome c release, and activities of caspases-9, -3, and -6 were decreased by resveratrol. Pretreatment with Z-VEID-FMK (benzyloxycarbonyl-Leu-Glu-His-Asp-fluoromethyl ketone) synergistically promoted resveratrol's protection against DNA fragmentation and cell apoptosis. Therefore, this study shows that resveratrol can protect CECs from oxLDL-induced apoptotic insults via downregulating Lox-1-mediated activation of the Bax-mitochondria-cytochrome c-caspase protease pathway.
脑血管内皮细胞（CECs）是血脑屏障的重要组成部分。我们之前的研究表明，氧化型低密度脂蛋白（oxLDL）诱导 CECs 凋亡。本研究旨在进一步评估白藜芦醇对 oxLDL 诱导的 CEC 损伤的作用及其可能的分子机制。白藜芦醇可降低 LDL 氧化为 oxLDL。此外，白藜芦醇减轻了 oxLDL 引起的氧化应激和细胞损伤。暴露于 oxLDL 的 CECs 会引起细胞收缩、DNA 片段化和细胞凋亡，但白藜芦醇可防止这种损伤。将 Lox-1 小干扰（si）RNA 应用于 CECs 可减少该膜受体的翻译，同时增加白藜芦醇对 oxLDL 诱导的细胞凋亡的保护作用。相比之下，过表达 Lox-1 则减弱了白藜芦醇的保护作用。白藜芦醇抑制 oxLDL 诱导的 Lox-1 mRNA 和蛋白表达。白藜芦醇和 Lox-1 siRNA 均降低了 oxLDL 增强的促凋亡 Bcl-2 相关 X 蛋白（Bax）从细胞质向线粒体的易位。随后，oxLDL 诱导的线粒体膜电位、细胞色素 c 释放以及 caspase-9、-3 和 -6 的活性降低均被白藜芦醇减弱。Z-VEID-FMK（苯甲氧基羰基-Leu-Glu-His-Asp-氟甲基酮）预处理可协同促进白藜芦醇对 DNA 片段化和细胞凋亡的保护作用。因此，本研究表明，白藜芦醇可通过下调 Lox-1 介导的 Bax-线粒体-细胞色素 c-caspase 蛋白酶通路的激活来保护 CECs 免受 oxLDL 诱导的凋亡损伤。
