LGMD 2A protein calpain 3 and its binding to titin

描述(由申请人提供)：所建议的调查目标 这里是为了研究Calain 3和Titin之间的分子相互作用，以及 为了测试这些相互作用中的扰动是否会在正常情况下产生缺陷 肌肉发生。Calain 3零突变导致虚弱的发现 肢带型肌营养不良症2A型，表明Calain 3是重要的 维持正常的肌肉动态平衡。然而，生理关系之间的关系 钙蛋白3缺乏和肌营养不良是未知的，主要是因为缺乏 的正常功能和相互作用的信息。它 在此提出了钙蛋白3与肌动蛋白以大分子形式存在， 肌肉中功能复合体，以及复合体的扰动可能导致 在肌病方面。几个观察结果支持这样一种观点，即 肌动蛋白或其结合体可引起肌病。如果CalPain 3也被证明 成为肌肉中的一种肌动蛋白结合蛋白，这将进一步促进我们的 了解Calain 3的基本生物学，也是我们对 肌动蛋白大分子复合体缺陷与肌肉的关系 疾病。然而，目前对肌动蛋白和肌动蛋白之间关系的认识 由于很难分离出不稳定的Calain，所以Calain 3很少 3蛋白质。尽管已经证明Calain与酵母中的肌动蛋白结合 双杂交分析，这种相互作用是否真的发生在肌肉和 它是否具有重要的生理意义仍不得而知。这项调查 这里提出的是为了研究calain 3和 肌肉中的肌动蛋白，并检验瘦与钙蛋白酶相互作用的假说 3对正常的肌肉发生和肌肉结构很重要。具体目标 包括： (目标1)检验Calain 3表达变化或 结构导致转基因小鼠的肌源性表型发生变化。 (目的2)验证Calain 3与肌动蛋白在肌肉中相互作用的假说， 并确定该结合的功能重要结构域。 (目标3)测试C3与titin的相互作用是否为正常所必需 肌肉发生。

DESCRIPTION (provided by applicant): The goals of the investigation proposed here are to examine the molecular interactions between calpain 3 and titin, and to test whether perturbations in those interactions create defects in normal myogenesis. The finding that null mutations in calpain 3 result in debilitating limb girdle muscular dystrophy type 2A, indicates that calpain 3 is important for normal muscle homeostasis. However, the physiological relationship between calpain 3 deficiency and muscular dystrophy is unknown, largely because of lack of information concerning the normal function and interactions of calpain 3. It is proposed here that calpain 3 exists with titin in a macromolecular, functional complex in muscle, and that perturbations of the complex can result in myopathies. Several observations support the contention that defects in titin or its binding partners can cause myopathy. If calpain 3 were also proven to be a titin-binding protein in muscle, that would further advance both our understanding of the basic biology of calpain 3, but also our knowledge of the relationship between defects in the titin macromolecular complex and muscle disease. However, current knowledge of the relationship between titin and calpain 3 is scant, because of the difficulty of isolating the unstable calpain 3 protein. Although it has been demonstrated that calpain binds titin in yeast two-hybrid assays, whether this interaction actually occurs in muscle and whether it is physiologically important remain unknown. The investigation proposed here is designed to examine the relationship between calpain 3 and titin in muscle, and to test the hypothesis that thin interactions with calpain 3 are important for normal myogenesis and muscle structure. The specific aims are: (Aim 1) To test the hypothesis that changes in calpain 3 expression or structure produce alterations in the myogenic phenotype of transgenic mice. (Aim 2) To test the hypothesis that calpain 3 interacts with titin in muscle, and to determine the functionally important domains for that binding. (Aim 3) To test whether C3 interactions with titin are required for normal myogenesis.