Muscular Dystrophy Specialized Research Center: Project 1

项目1 项目概要 我们研究的总体目标是阐明潜在的细胞和分子机制 肌营养不良症，以促进合理设计新的治疗策略和定量 评估靶点参与和治疗方法有效性的测定。我们目前的研究 重点关注肌营养不良症，这是一组由以下原因引起的先天性/肢带型肌营养不良症 细胞外基质（ECM）受体α-肌营养不良聚糖（α-DG）的翻译后加工缺陷。 含有层粘连蛋白 G 样 (LG) 结构域的 ECM 蛋白通过独特的杂多糖与 α-DG 结合 [-GlcA-β1,3-Xyl-α1,3-]n 称为基质聚糖。遗传学研究表明，至少任何一项的突变 编码 α-DG 翻译后加工所需酶的 18 个基因导致缺乏 或基质聚糖减少，从而损害 α-DG 受体功能。尽管取得了重大进展 虽然在肌聚糖病基因的鉴定和表征方面已经取得了进展，但我们仍然没有完全了解 了解基质聚糖的生化和生理功能，或基质聚糖的缺失或减少如何 长度会导致肌肉萎缩症。拟议研究的总体目标是提供机制 深入了解基质聚糖在 α-DG 受体功能和病理生理学中的作用 肌营养不良症。我们研究的总体假设是透彻理解 (a) 肌聚糖病患者中基质聚糖结构缩短并导致 α-DG 受体功能障碍 (b) 肌营养不良症病理生理学的潜在机制将导致更多 可靠的诊断和新颖的治疗策略。具体目标 1 将建立以下关系： 对照和对照中 α-DG 基质聚糖长度和 α-DG 上基质聚糖的层粘连蛋白结合特性 肌聚糖病患者的成纤维细胞和肌肉活检。这些研究将揭示异常 α-DG 的翻译后加工导致基质聚糖较短，与层粘连蛋白的亲和力降低 导致肌肉萎缩症。具体目标 2 将定义基质聚糖合成的生化调节 及其在α-DG受体功能中的作用。这些研究将确定基质聚糖的要求 合成以及蛋白质-蛋白质和蛋白质-糖相互作用如何调节其合成。具体目标 3 将定义肌营养不良症病理生理学的新机制并确定 改善肌肉功能所需的结构和层粘连蛋白结合特性。这些研究将使用 具有已确定的营养不良性肌肉病理学的 myd 小鼠，在 LARGE 基因之前和之后进行评估 转移。总的来说，这些目标将提供对潜在病理机制的理解 肌营养不良症，这将需要为设计新的诊断和治疗方法奠定基础。 治疗策略以及监测治疗参与和疗效的方法。

Project 1 Project Summary The overall goal of our research is to elucidate the cellular and molecular mechanisms that underly muscular dystrophies in order to facilitate the rational design of novel therapeutic strategies and quantitative assays to assess target engagement and the effectiveness of therapeutic approaches. Our current research focuses on the dystroglycanopathies, a group of congenital/limb-girdle muscular dystrophies caused by defects in post-translational processing of the extracellular matrix (ECM) receptor α-dystroglycan (α-DG). ECM proteins that contain laminin-G-like (LG) domains bind to α-DG via a unique heteropolysaccharide [-GlcA-β1,3-Xyl-α1,3-]n called matriglycan. Genetic studies have shown that mutations in any one of at least eighteen genes encoding enzymes required for α-DG post-translational processing lead to the absence of or a reduction in matriglycan and thus impair α-DG receptor function. Although significant progress has been made in the identification and characterization of dystroglycanopathy genes, we still do not fully understand the biochemical and physiological function of matriglycan, or how its absence or reduction in length causes muscular dystrophy. The overall objective of the proposed research is to provide mechanistic insights into the role matriglycan plays in α-DG receptor function and in the pathophysiology of the dystroglycanopathies. The overarching hypothesis of our research is that a thorough understanding of (a) the shortened matriglycan structure and resulting α-DG receptor dysfunction in dystroglycanopathy patients and (b) the mechanisms underlying the pathophysiology of the dystroglycanopathies, will lead to more reliable diagnostics and novel therapeutic strategies. Specific Aim 1 will establish the relationship between α-DG matriglycan length and laminin-binding properties of matriglycan on α-DG in control and dystroglycanopathy patient fibroblasts and muscle biopsies. These studies will reveal abnormalities in the post-translational processing of α-DG that result in shorter matriglycan with reduced affinity for laminin leading to muscular dystrophy. Specific Aim 2 will define the biochemical regulation of matriglycan synthesis and its role in the receptor function of α-DG. These studies will define the requirements for matriglycan synthesis and how its synthesis is regulated by protein-protein and protein-sugar interactions. Specific Aim 3 will define novel mechanisms underlying the pathophysiology of the dystroglycanopathies and determine the structure and laminin binding properties required to improve muscle function. These studies will use myd mice with established dystrophic muscle pathology that are evaluated before and after LARGE gene transfer. Collectively, these aims will provide an understanding of the pathological mechanisms underlying dystroglycanopathies, which will be needed to develop a rationale for the design of novel diagnostic and therapeutic strategies, as well as approaches to monitoring therapeutic engagement and efficacy.