Signalling via Dystrobrevin in Muscular Dystrophy

肌营养不良蛋白复合体在维持肌肉健康方面的一个主要功能是在收缩过程中为肌膜提供机械稳定性。然而，新的证据支持dystrophin复合体的信号和/或支架功能，这表明治疗方法的新可能性。也许信号机制参与肌肉营养不良的最令人信服的证据来自患上肌肉营养不良的α-dystrobrevin基因缺失小鼠。与它的dystrophin缺失小鼠不同，根据染料摄取研究判断，α-dystrobrevin缺失小鼠几乎没有表现出肌膜不稳定的迹象。为了了解α-肌营养不良蛋白异常导致肌营养不良症的机制，我们将确定α-肌营养不良蛋白的结构域 这对于挽救营养不良表型很重要。然后将鉴定与α-营养不良反应蛋白关键区域相关的蛋白质。此外，我们还将测试一种假说，即上调α-dystrobrevin，它与dystrophin复合体的几种蛋白质相互作用，将改善MDX小鼠的肌肉退化。一种新设计的棕榈酰化形式的α-dystrobrevin，在缺乏 营养不良蛋白在这些实验中将特别重要。最后，我们将研究缺乏α-dystrobrevin对肌肉基因表达的影响。我们利用基因芯片阵列技术对α-dystrobrevin基因缺失小鼠骨骼肌组织中的基因变化进行了深入的研究。要确定这些更改中的哪些发生在 肌肉细胞本身，而不是参与炎症反应的入侵细胞，我们将使用来自卫星细胞的克隆性肌肉细胞系。骨骼肌组织中变化的基因的表达将在这些纯粹的肌肉细胞中进行检测。一个特别耐人寻味的变化，尼曼-皮克C1基因表达的减少，将被详细研究，以确定它在肌肉退化中的可能作用。我们预期这些研究将会 提供有关dystrophin复合体信号传递能力的新信息，确定α-dystrobrevin在这一过程中的作用，并通过对dystrophin复合体介导的信号转导的操纵来建议新的治疗方法。

A major function of the dystrophin complex in maintaining muscle health is to provide mechanical stability to the sarcolemma during contraction. Emerging evidence, however, supports a signaling and/or scaffolding function for the dystrophin complex, which suggests new possibilities for therapeutic approaches. Perhaps the most convincing evidence for the involvement of a signaling mechanism in muscular dystrophy comes from the alpha-dystrobrevin null mouse which develops muscular dystrophy. Unlike its dystrophin null counterpart, the mdx mouse, the alpha-dystrobrevin null mouse shows little if any sign of sarcolemmal instability, as judged by dye uptake studies. To understand the mechanism by which alpha-dystrobrevin abnormalities cause muscular dystrophy, we will determine the domains of alpha-dystrobrevin that are important for rescue of the dystrophic phenotype. The proteins that associate with critical regions of alpha-dystrobrevin will then be identified. In addition, we will test the hypothesis that upregulation of alpha-dystrobrevin, which interacts with several proteins of the dystrophin complex, will ameliorate muscle degeneration in the mdx mouse. A newly-designed palmitoylated form of alpha-dystrobrevin that associates with the sarcolemma in the absence of dystrophin will be especially important in these experiments. Finally, we will examine the impact of the absence of alpha-dystrobrevin on muscle gene expression. We have conducted a thorough study of the gene changes in skeletal muscle tissue from alpha-dystrobrevin null mice using gene chip array technology. To determine which of these changes occur in muscle cells per se, as opposed to invading cells involved in the inflammatory response, we will use clonal muscle cells lines derived from satellite cells. The expression of genes that change in skeletal muscle tissue will be examined in these pure muscle cells. One particularly intriguing change, a decrease in expression of the Niemann-Pick C1 gene, will be examined in detail to determine its possible role in muscle degeneration. We expect that these studies will provide new information about the signaling capabilities of the dystrophin complex, define the role of alpha-dystrobrevin in this process, and suggest new approaches to therapy via manipulation of signal transduction mediated by the dystrophin complex.