Oxidative Stress and the Development of Osteoarthritis

项目总结： 该项目的长期目标是确定氧化作用的基本机制。 应激状态对骨性关节炎(OA)的发病具有特异性和直接的作用 特别关注与年龄相关的骨性关节炎。线粒体功能障碍，这是骨性关节炎患者衰老的标志， 通过促进细胞氧化应激，促进与年龄相关的疾病。而不是简单地 对细胞和组织造成随机氧化损伤，现代对氧化应激的定义 强调偏向氧化剂的不平衡会导致正常氧化还原信号的中断。这个 本项目在人类细胞和组织以及衰老小鼠中提供了氧化作用的证据 源自线粒体的应激通过以下途径破坏软骨细胞信号对骨关节炎的贡献 蛋白质硫醇氧化过度。这导致抑制促生存和促合成代谢的Akt和 Smad信号和促进促死亡和促分解代谢的p38信号。与一项 过氧化氢的线粒体来源，过表达人过氧化氢酶的转基因小鼠靶向 线粒体发生的年龄相关性骨性关节炎较少。我们还发现，病理水平的过氧化氢抑制了 JNK2信号转导和JNK2基因敲除小鼠发生更严重的年龄相关性骨性关节炎。过氧化还蛋白(Prxs) 是氧化还原信号的主要调节者，因为它们在细胞中含量丰富，并且与 过氧化氢。我们发现了通过过氧化使Prxs失活的证据，包括 线粒体Prx3干扰软骨细胞信号转导，包括Akt和JNK2对p38的抑制 激活会导致细胞死亡。这些发现支持了我们的总体假设，即在OA中， 病理水平的ROS，包括线粒体过氧化氢，抑制合成代谢，促进分解代谢和 细胞死亡信号通过过度的蛋白质硫醇氧化。为了验证这一假设，我们的目标是：1) 确定线粒体过氧化还蛋白-3(Prx3)过氧化的机制 在氧化应激条件下扰乱软骨细胞的信号。我们将检验这一假设 Prx3的过度氧化导致特定信号蛋白中的硫醇氧化有利于 分解代谢和细胞死亡途径超过合成代谢和细胞生存途径。2)确定效果 转基因Prx3过表达对小鼠骨性关节炎发生的影响。这一目标将考验 Prx3过度表达会减少年龄相关性骨性关节炎的假说。这些研究将改变这一领域 从关注随机氧化损伤作为衰老和氧化应激的机制 促进OA对紊乱的氧化还原信号的作用的理解。这个机制是 了解这一点很重要，因为针对调节氧化还原的特定蛋白质进行治疗 信令是可行的，是一个活跃的研究领域，并有望比 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.