Glutaredoxin, Macrophage Death and Atherosclerosis

描述（由申请人提供）：谷氧还蛋白（Grx）是氧化还原信号传导的重要调节剂，也是谷胱甘肽依赖性抗氧化系统的关键酶，可保护细胞免受氧化损伤。大量的研究提供证据表明，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形成中起着重要作用，但尚未研究Grx对巨噬细胞损伤和动脉粥样硬化病变的发展和进展的影响。体内巨噬细胞损伤和细胞死亡的机制尚不清楚。电子显微镜研究表明，在人类动脉粥样硬化病变，细胞死亡的主要模式是细胞凋亡，但胀亡，这是与强烈的炎症反应，因此与动脉粥样硬化病变进展。最近，我们证明，在人类单核细胞衍生的巨噬细胞氧化低密度脂蛋白（OxLDL）促进细胞死亡的半胱天冬酶独立的过程类似胀亡。我们继续表明，OxLDL诱导的巨噬细胞死亡涉及线粒体功能障碍，并通过过氧自由基形成介导，但ROS形成本身不能解释OxLDL的细胞毒性。我们的初步数据现在表明，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物的消耗。这种消耗过程导致谷胱甘肽/谷胱甘肽二硫化物比率的崩溃，这是一种有利于在称为蛋白质-S-谷胱甘肽化的反应中形成反应性蛋白硫醇和谷胱甘肽之间的混合二硫化物的条件。我们的研究表明，巯基氧化应激和蛋白-S-谷胱甘肽氧化诱导的氧化低密度脂蛋白促进巨噬细胞死亡。siRNA介导的Grx（负责蛋白脱谷胱甘肽化的酶）抑制增强了OxLDL诱导的巨噬细胞损伤，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展和进展的主要因素，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会防止巨噬细胞死亡，而且还可能降低动脉粥样硬化的严重程度。拟议的研究将测试这一假设，并检查Grx介导的保护巨噬细胞免受线粒体功能障碍和细胞死亡的可能分子机制。

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.