Sarcolipin in Duchenne Muscular Dystrophy

项目摘要 杜氏肌营养不良症（DMD）是最常见的致死性肌肉萎缩性疾病， 肌营养不良蛋白缺乏症。对于这种疾病没有有效的治疗方法。目前的治疗策略 旨在替代或弥补肌营养不良蛋白缺乏的药物也面临重大挑战， 心脏和呼吸道组织以及纤维化。因此，最近的研究集中在直接防止 营养不良过程的后果。确定这种替代疗法可以补充现有的 战略和提高治疗这种致命疾病的有效性。细胞内钙离子异常 超负荷是一种重要的早期致病事件，它启动并维持DMD的疾病进展。 我们最近发现肌磷脂（sarcolipin，SLN）是一种有效的肌浆网/内质网Ca~（2+）ATP酶抑制剂， 在DMD小鼠模型的骨骼肌和心肌中，SERCA（SERCA）显著增加。类似于 在啮齿类动物中，SLN水平在DMD犬模型的成肌细胞和肌肉中以及 DMD患者。在肌肉细胞中，SERCA占兴奋期间从胞质溶胶中去除Ca2+的≥ 70%。 收缩耦合因此，在营养不良的肌肉中，高水平的SLN对SERCA的慢性抑制可以 主要导致胞浆Ca~（2+）异常升高。因此，降低SLN表达是 预期可改善SERCA功能，恢复细胞内Ca2+稳态并减少营养不良 病理为了实现这一目标，我们在DMD小鼠模型中基因消融SLN表达。初步 研究表明SLN表达的减少足以改善SERCA功能并减轻DMD。 在这里，我们建议评估潜在的机制，SLN减少减轻骨骼肌 病理学和心肌病。此外，我们建议确定是否 靶向SLN表达在临床前环境中减轻DMD。我们将具体测试以下内容 假设：1）SLN过表达限制DMD中骨骼肌再生，2）SLN减少 表达可以改善心脏SERCA功能并预防心肌病，和3）出生后AAV介导的 SLN基因沉默治疗可改善DMD。这些研究的结果将确定SLN是一种 是治疗DMD和相关心肌病的潜在治疗靶点。

PROJECT SUMMARY Duchenne muscular dystrophy (DMD) is the most common lethal muscle wasting disease caused by dystrophin deficiency. There is no effective treatment exists for this disease. The current therapeutic strategies aimed to either replace or compensate for the lack of dystrophin also face major challenges such as targeting cardiac and respiratory tissues and fibrosis. Therefore, recent studies are focused to prevent directly the consequences of dystrophic process. Identification of such alternative therapies could complement the existing strategies and enhance the effectiveness of treatment for this lethal disease. Abnormal intracellular Ca2+ overload is an important, early pathogenic event that initiates and perpetuates disease progression in DMD. We recently found that sarcolipin (SLN), a potent inhibitor of sarco/endoplasmic reticulum Ca2+ ATPase (SERCA), is significantly increased in the skeletal and cardiac muscles of mouse models of DMD. Similar to rodents, SLN levels are high in myoblasts and muscles of a canine model of DMD and in muscle biopsies of DMD patients. In muscle cells, SERCA accounts for ≥ 70% of Ca2+ removal from the cytosol during excitation- contraction coupling. Therefore in dystrophic muscles, chronic inhibition of SERCA by high-levels of SLN could majorly contribute to the abnormal elevation of cytosolic Ca2+. Accordingly, reducing SLN expression is anticipated to improve SERCA function, restore intracellular Ca2+ homeostasis and reduce dystrophic pathology. Towards this goal, we genetically ablated SLN expression in mouse models of DMD. Preliminary studies suggest that reduction in SLN expression is sufficient to improve SERCA function and mitigate DMD. Here, we propose to evaluate the potential mechanisms by which SLN reduction mitigates skeletal muscle pathology and cardiomyopathy in mouse models of DMD. In addition, we propose to determine whether targeting SLN expression mitigate DMD in preclinical settings. We will specifically test the following hypotheses: 1) SLN overexpression limits skeletal muscle regeneration in DMD, 2) Reduction in SLN expression can improve cardiac SERCA function and prevent cardiomyopathy, and 3) Postnatal AAV mediated SLN gene silencing therapy can ameliorate DMD. The outcomes of these studies will identify SLN as a potential therapeutic target for the treatment of DMD and associated cardiomyopathy.