NADPH Oxidase and Autophagic Dysfunction in Duchenne Muscular Dystrophy

项目摘要 杜氏肌营养不良症（DMD）是一种破坏性类型的肌营养不良症，发病率为1/ 每3500名男性。DMD是一种X染色体连锁的肌肉萎缩性疾病，由细胞骨架蛋白突变引起。 抗肌萎缩蛋白。年轻的DMD患者经历肌肉损伤，然后再生;然而， 随着疾病的进展，再生受到阻碍，肌肉纤维逐渐被 结缔组织和脂肪沉积。严重的肌肉无力导致活动能力下降10至12 年龄，并最终在20至30岁时因呼吸和/或心力衰竭而死亡。虽然 目前尚无治疗该病的方法，许多不同的治疗DMD的方法正在进入临床 审判越来越多的证据支持这样的观点，即mdx肌肉对损伤的敏感性增加， 与肌膜Ca 2+内流增加和活性氧产生增加相关 物种（ROS）。受损的自噬，一种清除受损成分的细胞过程，最近被 与疾病进程有关。我们小组正在进行的工作发现， Nox 2对小鼠骨骼肌氧化还原平衡和Ca 2+稳态的影响 肌营养不良症（Mdx）。我们最近发现Src是一种非受体酪氨酸激酶， 开关以激活Nox 2。Nox 2的遗传抑制减少了旺盛的ROS产生，降低了Src 激酶活性，并拯救来自Mdx小鼠的骨骼肌中有缺陷的自噬。此外，我们有 显示在体外抑制Src激酶降低氧化应激并改善自噬。初步 我们最近发现，用Src激酶抑制剂达沙替尼治疗Mdx小鼠， 流量和骨骼肌功能。本提案的总体目标是测试Src激酶的抑制是否 可预防Mdx小鼠的氧化应激、受损的自噬流和肌肉病理。如果成功， 这项研究将为DMD提供一个新的治疗靶点Src激酶。鉴于Src激酶 抑制剂正在临床开发用于治疗癌症，这些研究的结果将对 未来治疗DMD的临床试验。

Project Summary Duchenne muscular dystrophy (DMD) is a devastating type of muscular dystrophy, with an incidence of 1 in every 3500 males. DMD is an X-linked, muscle-wasting disease caused by mutations in the cytoskeletal protein dystrophin. Young DMD patients experience muscle damage that is followed by regeneration; however, as the disease progresses regeneration is impeded and muscle fibers are progressively replaced by connective tissue and fatty deposits. Profound muscle weakness results in decreased mobility by 10 to 12 year of age and eventually death by the age of 20 to 30 due to respiratory and/or cardiac failure. While there is currently no treatment for the disease, many different therapeutic approaches for DMD are entering clinical trials. Accumulating evidence supports the idea that the elevated susceptibility to damage in mdx muscles correlates with the presence of increased sarcolemmal Ca2+ influx and increased production of reactive oxygen species (ROS). Impaired autophagy, a cellular process to clear damaged constituents, has recently been implicated in the disease process. Ongoing work by our group has found that increased ROS generation from Nox2 contributes to altered redox balance and Ca2+ homeostasis in skeletal muscle from the mouse model of muscular dystrophy (Mdx). We have recently shown that Src, a non-receptor tyrosine kinase, acts as a redox switch to activate Nox2. Genetic inhibition of Nox2 decreases the exuberant ROS generation, decreases Src kinase activity, and rescues the defective autophagy in skeletal muscle from Mdx mice. Furthermore, we have shown that inhibiting Src kinase in-vitro decreases oxidative stress and improves autophagy. In preliminary data we have recently found that treating Mdx mice with the Src kinase inhibitor dasatinib improves autophagic flux and skeletal muscle function. The overall goal of this proposal is to test whether inhibition of Src kinase can prevent oxidative stress, impaired autophagic flux, and muscle pathology in Mdx mice. If successful, the proposed research will provide a novel therapeutic target, Src kinase, for DMD. Given that Src kinase inhibitors are in clinical development for the treatment of cancer, results from these studies will be valuable for future clinical trials for the treatment of DMD.