NADPH Oxidase and Autophagic Dysfunction in Duchenne Muscular Dystrophy

项目摘要 Duchenne肌营养不良症(DMD)是一种毁灭性的肌营养不良症，发病率为1/4。 每3500只雄性。DMD是一种X连锁的肌肉萎缩疾病，由细胞骨架突变引起 蛋白营养不良蛋白。年轻的DMD患者会经历肌肉损伤，然后是再生；然而， 随着疾病的发展，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行动能力下降10-12 因呼吸和/或心脏衰竭，最终在20岁至30岁时死亡。趁有机会 目前还没有针对这种疾病的治疗方法，许多不同的治疗方法正在进入临床 审判。越来越多的证据支持这样一种观点，即MDX肌肉对损伤的敏感性增加 与肌膜钙内流增加和活性氧产生增加相关 种(ROS)。受损的自噬是一种清除受损成分的细胞过程，最近 与疾病过程有牵连。我们团队正在进行的研究发现，从 NOX2参与小鼠骨骼肌氧化还原平衡和钙稳态的改变 肌营养不良(MDX)。我们最近发现，非受体酪氨酸激酶Src起着氧化还原的作用 切换到激活NOX2。NOX2的基因抑制减少了旺盛的ROS生成，减少了Src KK活性，并挽救MDX小鼠骨骼肌中有缺陷的自噬。此外，我们还拥有 研究表明，在体外抑制Src激酶可以减少氧化应激并改善自噬。在预赛中 我们最近发现，用Src激酶抑制剂达沙替尼治疗MDX小鼠可提高自噬能力 流量和骨骼肌功能。这项提议的总体目标是测试对Src激酶的抑制 可预防氧化应激、受损的自噬通量和MDX小鼠的肌肉病理。如果成功，则 拟议中的研究将为DMD提供一个新的治疗靶点--Src激酶。考虑到Src蛋白激酶 抑制物正处于治疗癌症的临床开发中，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.