Glutaredoxin, Macrophage Death and Atherosclerosis

描述（由申请人提供）：Glutaredoxin （Grx）是氧化还原信号的重要调节剂，也是谷胱甘肽依赖的抗氧化系统的关键酶，可以保护细胞免受氧化损伤。大量研究证明巨噬细胞损伤和细胞死亡是动脉粥样硬化病变发展的主要因素。虽然自由基和氧化应激在动脉粥样硬化发生中起核心作用，但Grx对巨噬细胞损伤和动脉粥样硬化病变发生进展的影响尚未研究。体内巨噬细胞损伤和细胞死亡的机制尚不清楚。电镜研究表明，在人类动脉粥样硬化病变中，细胞死亡的主要模式不是细胞凋亡，而是肿瘤，这与强烈的炎症反应有关，因此与动脉粥样硬化病变进展有关。最近，我们证明了在人类单核细胞来源的巨噬细胞中，氧化LDL （OxLDL）以一种类似于肿瘤的caspase非依赖性过程促进细胞死亡。我们进一步表明，OxLDL诱导的巨噬细胞死亡涉及线粒体功能障碍，并由过氧自由基形成介导，但ROS的形成不能单独解释OxLDL的细胞毒性。我们现在的初步数据表明，OxLDL也促进还原型谷胱甘肽的大量消耗，并在较小程度上促进谷胱甘肽二硫化。这种消耗过程导致谷胱甘肽/谷胱甘肽二硫比的崩溃，这种情况有利于在反应蛋白硫醇和谷胱甘肽之间形成混合二硫，这种反应被称为蛋白质- s -谷胱甘肽酰化。我们的研究表明，由OxLDL诱导的硫醇氧化应激和蛋白- s -谷胱甘肽化促进巨噬细胞死亡。Grx是一种负责蛋白质去谷胱甘肽化的酶，sirna介导的Grx抑制增强了oxldl诱导的巨噬细胞损伤，这表明Grx是保护巨噬细胞免受oxldl诱导的细胞死亡所必需的。由于巨噬细胞死亡似乎是动脉粥样硬化病变发生和进展的主要因素，增加巨噬细胞对病理生理蛋白- s -谷胱甘肽化的保护可能不仅可以防止巨噬细胞死亡，还可以降低动脉粥样硬化的严重程度。拟议的研究将验证这一假设，并研究grx介导的巨噬细胞线粒体功能障碍和细胞死亡保护的可能分子机制。

DESCRIPTION (provided by applicant): Glutaredoxin (Grx) is an important regulator of redox signaling and a key enzyme of the glutathione- dependent antioxidant system, which protects cells against oxidative injury. Numerous studies provide evidence that macrophage injury and cell death are major factors in the development of atherosclerotic lesions. Although free radicals and oxidative stress play a central role in atherogenesis, the impact of Grx on macrophage injury and the development and progression of atherosclerotic lesions has not been studied. The mechanisms underlying macrophage injury and cell death in vivo are unclear. Electron microscopy studies indicate that in human atherosclerotic lesions, the predominant mode of cell death is not apoptosis but oncosis, which is associated with an intense inflammatory response and hence with atherosclerotic lesion progression. Recently we demonstrated that in human monocyte-derived macrophages oxidized LDL (OxLDL) promotes cell death in a caspase-independent process resembling oncosis. We went on to show that OxLDL-induced macrophage death involves mitochondrial dysfunction and is mediated by peroxyl radical formation but that ROS formation alone cannot explain OxLDL cytotoxicity. Our preliminary data now demonstrate that OxLDL also promotes the massive depletion of reduced glutathione and to a lesser extent, of glutathione disulfide. This depletive process results in the collapse of the glutathione/glutathione disulfide ratio, a condition that favors the formation of mixed disulfides between reactive protein thiols and glutathione in a reaction referred to as protein-S-glutathionylation. Our studies show that thiol oxidative stress and protein-S-glutathionylation induced by OxLDL promote macrophage death. siRNA-mediated inhibition of Grx, the enzyme responsible for the degluathionylation of proteins, potentiated OxLDL-induced macrophage injury, indicating that Grx is required to protect macrophages from OxLDL-induced cell death. Because macrophage death appears to be a major contributing factor to the development and progression of atherosclerotic lesions, increasing the macrophage's protection against pathophysiological protein-S- glutathionylation likely will not only prevent macrophage death but may also decrease the severity of atherosclerosis. The proposed studies will test this hypothesis and examine possible molecular mechanisms of Grx-mediated protection of macrophages from mitochondrial dysfunction and cell death.