OxLDL triggers retrograde translocation of arginase2 in aortic endothelial cells via ROCK and mitochondrial processing peptidase.
OxLDL triggers retrograde translocation of arginase2 in aortic endothelial cells via ROCK and mitochondrial processing peptidase.
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OXLDL通过岩石和线粒体加工肽酶在主动脉内皮细胞中精氨酸酶2的逆转转移。
DOI：
10.1161/circresaha.115.304262
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发表时间：
2014-08-01
影响因子：
20.1
通讯作者：
Romer LH
中科院分区：
文献类型：
--
作者：
Pandey D;Bhunia A;Oh YJ;Chang F;Bergman Y;Kim JH;Serbo J;Boronina TN;Cole RN;Van Eyk J;Remaley AT;Berkowitz DE;Romer LH
精氨酸酶活性的增加通过对l -精氨酸底物的竞争和NOS的相互调节导致内皮功能障碍。暴露于氧化LDL的人主动脉内皮细胞（HAEC）中精氨酸酶活性的快速增加与翻译后修饰或亚细胞运输一致。为了验证OxLDL触发线粒体精氨酸酶2 （Arg2）向胞浆的反向易位和Arg2激活的假设，并且该过程依赖于线粒体加工肽酶（MPP）、LOX-1受体和ROCK。在HAEC和小鼠主动脉内膜中，OxLDL触发了Arg2从线粒体到细胞质的易位，同时精氨酸酶活性升高。所有这些变化都可以通过抑制MPP或sirna介导的敲低而消除。在KO小鼠中，ROCK抑制和LOX-1受体的缺失也会消除易位。Arg2的氨基末端测序显示了2个候选线粒体靶向序列，其中任何一个序列的缺失都将Arg2限制在细胞质中。MPP或LOX-1受体KO抑制剂可减弱oxldl介导的内皮特异性NO生成的减少和超氧化物生成的增加。最后，与ApoE−/−对照相比，在ApoE−/−背景下饲养的Arg2−/−小鼠表现出斑块负荷减少、ROS产生减少、NO增加和内皮功能改善。这些数据证明了Arg2（一种具有明确MTS的蛋白）在哺乳动物细胞中的双重分布，以及它在细胞外环境的改变中向细胞质的反向易位。这种新的分子机制驱动oxldl介导的精氨酸酶激活、eNOS解偶联、内皮功能障碍和动脉粥样硬化。
Increased arginase activity contributes to endothelial dysfunction by competition for L-arginine substrate and reciprocal regulation of NOS. The rapid increase in arginase activity in human aortic endothelial cells (HAEC) exposed to oxidized LDL is consistent with post-translational modification or subcellular trafficking. To test the hypotheses that OxLDL triggers reverse translocation of mitochondrial Arginase 2 (Arg2) to cytosol and Arg2 activation, and that this process is dependent upon mitochondrial processing peptidase (MPP), LOX-1 receptor and ROCK. OxLDL triggered translocation of Arg2 from mitochondria to cytosol in HAEC and in murine aortic intima with a concomitant rise in arginase activity. All of these changes were abolished by inhibition of MPP or by its siRNA-mediated knockdown. ROCK inhibition and the absence of the LOX-1 receptor in KO mice also ablated translocation. Amino-terminal sequencing of Arg2 revealed 2 candidate mitochondrial targeting sequences, and deletion of either of these confined Arg2 to the cytoplasm. Inhibitors of MPP or LOX-1 receptor KO attenuated OxLDL-mediated decrements in endothelial-specific NO production and increases in superoxide generation. Finally, Arg2−/− mice bred on an ApoE−/− background showed reduced plaque load, reduced ROS production, enhanced NO, and improved endothelial function as compared with ApoE−/− controls. These data demonstrate dual distribution of Arg2, a protein with an unambiguous MTS, in mammalian cells, and its reverse translocation to cytoplasm by alterations in the extracellular milieu. This novel molecular mechanism drives OxLDL-mediated arginase activation, eNOS uncoupling, endothelial dysfunction, and atherogenesis.