Sarcoglycan in Myopathy and Muscle Membrane Stability

项目总结 肌聚糖复合体稳定肌肉的质膜，编码基因的突变 肌聚糖亚单位产生一种脆弱的肌膜。肌膜断裂是骨骼的一般特征。 和心肌损伤，以及由肌营养不良蛋白或肌聚糖基因引起的肌病 突变。这项研究计划的主要目标是了解肌营养不良蛋白的机制 和肌糖可以稳定肌膜和确定肌肉营养不良的遗传修饰物。因为 我们推测，这些罕见的遗传性疾病与肌肉损伤有共同的特征，包括心肌损伤 肌聚糖突变的修饰物不仅对营养不良症起到类似的作用，而且对 一般都是肌肉损伤。我们使用肉糖病的小鼠模型Sgcg绘制了遗传修饰基因 缺少伽玛-肌聚糖的模型。之所以选择这个模型，是因为有强有力的证据表明 具有肌聚糖基因突变的人类中的修饰物。我们在Sgcg小鼠身上使用了交叉策略， 129个遗传背景中的轻度保护性表型和重度表型的优势 在有害的DBA背景下出现在Sgcg小鼠身上。我们成功地鉴定出了多种遗传修饰因子 包括潜伏的转化生长因子β结合蛋白4(LTBP4)和膜联蛋白A6(ANXA6)。两个修饰基因都是 在生物学上与损伤修复和恢复有关，并验证了该方法的实用性。与此相伴而生 进展，反义寡核苷酸介导的外显子的开发和批准有进展 跳跃治疗杜氏肌营养不良症。我们开发了一种类似的方法来治疗肢体 腰带型肌营养不良症(LGMD)2C，是γ-肌聚糖基因所致肌营养不良症的一种 突变。在上一期的支持中，我们展示了在从 多名LGMD 2C突变患者，表明Mini-Gamma，小的内部缺失形式 伽玛-肌聚糖稳定肌膜。我们现在将重点结合外显子跳跃和 修饰剂的方法，以诱导遗传纠正和促进肌膜稳定性。我们将开发临床前研究 支持外显子跳过的数据，并同时展示关于 肌膜稳定性与肌肉生长的关系。

PROJECT SUMMARY The sarcoglycan complex stabilizes the plasma membrane of muscle, and mutations in the genes encoding sarcoglycan subunits produce a fragile sarcolemma. Sarcolemmal disruption is a general feature of skeletal and cardiac muscle injury, as well as the myopathic disorders arising from dystrophin or sarcoglycan gene mutations. This research program has as its primary goal to understand the mechanisms by which dystrophin and sarcoglycan stabilize the sarcolemma and to identify genetic modifiers of muscular dystrophy. Because these rare genetic disorders share features with muscle injury, including cardiac muscle injury, we hypothesize that modifiers of sarcoglycan mutations will not only exert as similar effect on dystrophinopathies but also on muscle injury in general. We mapped genetic modifiers using a mouse model of sarcoglycanopathy, the Sgcg model which lacks gamma-sarcoglycan. This model was selected because there was strong evidence for modifiers in humans with sarcoglycan gene mutations. We used an intercross strategy in Sgcg mice, taking advantage of the mild protective phenotype seen in the 129 genetic background and the severe phenotype seen in Sgcg mice on the deleterious DBA background. We successfully identified multiple genetic modifiers including latent TGFβ binding protein 4 (LTBP4) and annexin A6 (ANXA6). Both modifier genes are biologically linked to injury repair and recovery and validate the utility of the method. Concomitant with this progress, there have advances in the development and approval of antisense oligonucleotide-mediated exon skipping as a therapy for Duchenne Muscular Dystrophy. We developed a similar approach to treat Limb Girdle Muscular Dystrophy (LGMD) 2C, which is the form of muscular dystrophy from γ-sarcoglycan gene mutations. In the last period of support, we showed the feasibility of exon skipping in cell lines generated from multiple patients with LGMD 2C mutations, demonstrating that Mini-gamma, the small internally deleted form of gamma-sarcoglycan stabilizes the sarcolemma. We will now focus on combining exon skipping together with modifier approaches to elicit genetic correction and promote sarcolemmal stability. We will develop preclinical data to support exon skipping and simultaneously demonstrate key biological mechanisms about the relationship between sarcolemmal stability and muscle growth.