Structure-Function Analysis of Sarcospan

描述(申请人提供)：在骨骼肌中，肌营养不良蛋白-糖蛋白复合体位于肌膜，由外周和完整的膜蛋白组成。作为一个整体，这个复合体将细胞外基质与细胞内肌动蛋白细胞骨架连接起来，并在肌肉收缩过程中为肌膜提供结构稳定性。Duchenne肌营养不良是最常见的营养不良形式，由dystrophin基因突变引起，该突变导致dystrophin蛋白和整个dystrophin-糖蛋白复合体的丢失。我的研究小组率先发现了几个与sarcospan功能相关的关键发现，sarcospan是dystrophin-糖蛋白复合体的一个组成部分。我们已经证明，Sarcospan在调节该复合体中的蛋白质相互作用方面发挥着重要作用。Sarcospan影响dystrophin-糖蛋白复合体和细胞外基质之间的通讯。重要的是，我们证明了在mdx小鼠中轻度sarcospan的过度表达，它具有小鼠肌营养不良蛋白基因的突变，通过稳定功能类似于dystrophin-糖蛋白复合体的蛋白质复合体的表达来拯救肌营养不良症。我的研究小组已经开发出二级基因的使用，如SSPN和Akt，作为改善营养不良肌肉的一种策略。这种方法的优势在于，它们有可能针对所有DMD病例，而不考虑特定的Dstrophin突变。目前的3R01提案建立在第一和第二个资助期的发现基础上，通过询问SSPN改善Dstrophin缺陷MDX小鼠疾病的具体机制。我们将测试SSPN在人源性DMD肌肉细胞中的有效性，并确定SSPN具有治疗作用的最小结构域。我们的研究将揭示SSPN在确定黏附复合体(DGC、UGC和α7？1整合素)的细胞表面表达中的伴侣功能，这些黏附复合体被认为是改善MDX疾病的。我们推测SSPN可能作为一个‘单一客户’的伴侣来调节肌肉中黏附复合体的细胞表面定位。该建议的结果将改变我们对DMD发病机制的理解，并为基于SSPN的治疗的发展提供必要的见解。我们将产生动物模型，这些模型将对该领域的许多未来项目具有价值。此外，我们预计我们的结果将阐明可以对抗由于失去细胞外基质接触而导致的广泛肌肉萎缩障碍的分子途径。

DESCRIPTION (provided by applicant): In skeletal muscle, the dystrophin-glycoprotein complex is located at the sarcolemma and is composed of peripheral and integral membrane proteins. As a whole, this complex links the extracellular matrix to the intracellular actin cytoskeleton and provides structural stability to the sarcolemma during muscle contraction. Duchenne muscular dystrophy, the most common form of dystrophy, is caused by mutations in the dystrophin gene that result in loss of dystrophin protein and the entire dystrophin-glycoprotein complex. My research group has pioneered several key discoveries related to the function of sarcospan, an integral component of the dystrophin-glycoprotein complex. We have shown that sarcospan plays an important role in mediating protein interactions within this complex. Sarcospan affects communication between the dystrophin-glycoprotein complex and the extracellular matrix. Importantly, we demonstrate that mild sarcospan over-expression in mdx mice, which possess a mutation in the murine dystrophin gene, rescues muscular dystrophy by stabilizing expression of a complex of proteins that is functionally analogous to the dystrophin-glycoprotein complex. My research group has developed the use of secondary genes, such as SSPN and Akt, as a strategy to ameliorate dystrophic muscle. Such approaches are advantages in that they have the potential to target all DMD cases, regardless of the specific dystrophin mutation. The current 3R01 proposal builds on discoveries made during the first and second funding period by interrogating specific mechanisms by which SSPN ameliorates disease in dystrophin-deficient mdx mice. We will test the efficacy of SSPN in human-derived DMD muscle cells and determine the minimal domains of SSPN that are therapeutic. Our studies will reveal a chaperone function for SSPN in determining the cell surface expression of adhesion complexes (DGC, UGC, and α7ß1 integrin) that are known to ameliorate mdx disease. We hypothesize that SSPN may function as a 'single-client' chaperone to regulate cell surface localization of adhesion complexes in muscle. The outcomes of the proposal will change our understanding of DMD pathogenesis and provide necessary insight for development of SSPN- based therapy. We will generate animal models that will be valuable for many future projects in the field. Furthermore, we expect that our results will illuminate molecular pathways that could counter a broad range of muscle wasting disorders due to loss of extracellular matrix contact.