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。我们建议研究SSPN介导的MDX表型改善的分子机制(S)，并揭示可能掩盖SSPN缺失小鼠潜在有趣和有启发性的表型的代偿机制。我们还将通过检查肌肉力学来完成对SSPN的“救援效应”的描述。我们的假设为跨膜/细胞骨架复合体(即整合素和DGC)之间的串扰提供了一种机制，可能解释补偿机制是如何调节的。每个AIMS的结果都将提供有关sarcospan作为营养不良蛋白-糖蛋白复合体中重要结构元件的作用的新信息，并揭示sarcospan在信号和疾病中的功能的新信息。公共卫生相关性我们的提案解决了与营养不良蛋白-糖蛋白复合体的破坏如何导致Duchenne肌营养不良症相关的问题。在我们之前的资助期间，我们发现Sarcospan，dystrophin-糖蛋白复合体的一个组成部分，能够改善小鼠的dystrophin缺乏性肌营养不良。我们计划测试这些小鼠的生理特性，并探讨萨科斯潘的改善机制。

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. We propose to investigate the molecular mechanism(s) of SSPN-mediated amelioration of mdx phenotype and reveal the compensatory mechanisms that may mask a potentially interesting and enlightening phenotype in the SSPN-null mice. We will also complete our characterization of SSPN's `rescue effect' by examining muscle mechanics. Our hypothesis provides a mechanism for cross-talk between transmembrane/cytoskeletal complexes (i.e. integrins and DGC) that may illuminate how compensatory mechanisms are regulated. Results from each of the Aims will provide new information on the role of sarcospan as an important structural element within the dystrophin-glycoprotein complex and uncover new information on sarcospan's function in signaling and disease. PUBLIC HEALTH RELEVANCE Our proposal addresses questions related to how disruption of the dystrophin-glycoprotein complex causes Duchenne muscular dystrophy. During our previous funding period, we discovered that sarcospan, an integral component of the dystrophin-glycoprotein complex, is able to ameliorate dystrophin-deficient muscular dystrophy in mice. We plan to test the physiological properties of these mice and investigate the mechanisms of sarcospan amelioration.