Oxidative Stress and the Development of Osteoarthritis

项目摘要： 该项目的长期目标是确定氧化的基本机制， 应力条件具体和直接有助于骨关节炎（OA）的发病机制， 特别关注与年龄相关的OA。线粒体功能障碍是OA中发现的衰老标志， 通过促进细胞氧化应激导致与年龄相关的病症。而不是简单 导致细胞和组织的随机氧化损伤，氧化应激的现代定义 强调有利于氧化剂的不平衡导致正常氧化还原信号的破坏。的 目前的项目已经在人体细胞和组织以及衰老小鼠中提供了证据， 源于线粒体的应激破坏软骨细胞信号传导，通过 过度的蛋白质巯基氧化。这导致了促存活和促合成代谢Akt的抑制， Smad信号传导与促死亡和促分解代谢p38信号传导的促进。一致的 H2 O2的线粒体来源，过表达人过氧化氢酶的转基因小鼠靶向H2 O2的线粒体来源。 线粒体发生较少的年龄相关性OA。我们还发现病理水平的H2 O2抑制 JNK 2信号转导和JNK 2敲除小鼠发生更严重的年龄相关性OA。过氧化物酶（Prxs） 是氧化还原信号的主要调节剂，因为它们在细胞中的丰度和与 过氧化氢我们发现了通过过度氧化导致Prxs失活的证据，包括 线粒体Prx 3，破坏软骨细胞信号传导，包括p38抑制Akt和JNK 2 激活导致细胞死亡。这些发现支持了我们的总体假设，即在OA中， 病理水平的ROS，包括线粒体H2 O2，抑制合成代谢和促进分解代谢， 细胞死亡信号通过过度的蛋白巯基氧化。为了验证这一假设，我们的目标是：1） 确定线粒体过氧化物酶-3（Prx 3）过度氧化的机制 在氧化应激条件下破坏软骨细胞信号传导。我们将检验这个假设 Prx 3过氧化导致特定信号蛋白中的蛋白硫醇氧化， 分解代谢和细胞死亡途径优于合成代谢和细胞存活途径。2)确定影响 转基因过表达Prx 3对小鼠OA发生的影响。这一目标将考验 假设Prx 3过表达将减少年龄相关OA。这些研究将改变这个领域 从关注随机氧化损伤作为衰老和氧化应激 促进OA理解受干扰的氧化还原信号的作用。这个机制是 重要的是要了解，因为治疗靶向的特定蛋白质，调节氧化还原 信号是可行的，是一个活跃的研究领域，并承诺比 使用非特异性抗氧化剂靶向随机氧化损伤。

Project Summary: The long-term objective of this project is to determine the basic mechanisms by which oxidative stress conditions specifically and directly contribute to the pathogenesis of osteoarthritis (OA) with a particular focus on age-related OA. Mitochondrial dysfunction, a hallmark of aging found in OA, contributes to age-related conditions through promoting cellular oxidative stress. Rather than simply causing random oxidative damage to cells and tissues, the modern definition of oxidative stress emphasizes that an imbalance in favor of oxidants leads to disruption of normal redox signaling. The present project has provided evidence in human cells and tissues and in aging mice that oxidative stress originating in the mitochondria disrupts chondrocyte signaling to contribute to OA through excessive protein thiol oxidation. This resulted in inhibition of pro-survival and pro-anabolic Akt and Smad signaling and promotion of pro-death and pro-catabolic p38 signaling. Consistent with a mitochondrial source of H2O2, transgenic mice that overexpress human catalase targeted to the mitochondria developed less age-related OA. We also found that pathologic levels of H2O2 inhibit JNK2 signaling and JNK2 knockout mice develop more severe age-related OA. Peroxiredoxins (Prxs) are major regulators of redox signaling due to their abundance in the cell and high reaction rates with H2O2. We found evidence linking inactivation of Prxs through hyperoxidation, including the mitochondrial Prx3, to disrupted chondrocyte signaling including Akt and JNK2 inhibition with p38 activation resulting in cell death. These findings support our overall hypothesis that in OA, pathological levels of ROS, including mitochondrial H2O2, inhibit anabolic and promote catabolic and cell death signaling through excessive protein thiol oxidation. To test this hypothesis our aims are: 1) Determine the mechanism by which mitochondrial peroxiredoxin-3 (Prx3) hyperoxidation disrupts chondrocyte signaling under oxidative stress conditions. We will test the hypothesis that Prx3 hyperoxidation results in oxidation of protein thiols in specific signaling proteins to favor catabolic and cell death pathways over anabolic and cell survival pathways. 2) Determine the effects of transgenic overexpression of Prx3 on the development of OA in mice. This aim will test the hypothesis that overexpression of Prx3 will reduce age-related OA. These studies will shift the field from a focus on random oxidative damage as the mechanism by which aging and oxidative stress promote OA to an understanding of the role of disturbed redox signaling. This mechanism is important to understand because therapeutic targeting of specific proteins that regulate redox signaling is feasible, is an active area of investigation, and promises to be much more effective than targeting random oxidative damage using non-specific anti-oxidants.