Sarcolipin in Duchenne Muscular Dystrophy

项目总结 Duchenne肌营养不良症(DMD)是最常见的致死性肌肉萎缩疾病，由 营养不良蛋白缺乏症。对于这种疾病，目前还没有有效的治疗方法。当前的治疗策略 旨在取代或弥补肌营养不良蛋白缺乏的人也面临着重大挑战，如靶向 心脏和呼吸组织与纤维化。因此，最近的研究集中在直接预防 营养不良过程的后果。这种替代疗法的确定可以补充现有的 战略和提高这一致命疾病的治疗效果。异常细胞内钙离子 过载是一种重要的早期致病事件，它启动并维持了DMD的疾病进展。 我们最近发现肌磷脂(SLN)，一种有效的肌浆网/内质网钙ATPase抑制剂 (SERCA)，在DMD模型的小鼠骨骼肌和心肌中显著增加。类似于 在啮齿类动物中，在DMD模型犬的成肌细胞和肌肉中SLN水平很高，在DMD犬的肌肉活检组织中也是如此 DMD患者。在肌肉细胞中，SERCA占≥70%的钙离子从胞浆中清除的兴奋- 收缩耦合。因此，在营养不良的肌肉中，高水平SLN对SERCA的慢性抑制可能 主要是细胞内钙离子异常升高所致。因此，减少SLN的表达是 有望改善SERCA功能，恢复细胞内钙稳态，减少营养不良 病理学。为了实现这一目标，我们在DMD小鼠模型中通过基因去除了SLN的表达。初步 研究表明，SLN表达的减少足以改善SERCA功能，减轻DMD。 在这里，我们建议评估SLN减少缓解骨骼肌的潜在机制。 DMD小鼠模型的病理学和心肌病。此外，我们建议确定是否 靶向SLN表达可缓解临床前环境中的DMD。我们将专门测试以下内容 假说：1)SLN过表达限制DMD骨骼肌再生，2)SLN减少 表达可改善心脏SERCA功能，预防心肌病；3)出生后AAV介导 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 DMD及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.