Targeting Membrane Repair in Muscular Dystrophy

描述（由申请人提供）：Duchenne肌营养不良（DMD）和由肌营养不良蛋白/肌营养不良蛋白聚糖复合物突变引起的其他营养不良至少部分由于肌膜脆性而产生病理学。其他几种形式的肌营养不良症与膜修复缺陷有关，包括与人类患者中的小窝蛋白-3（Cav 3）和dysferlin突变有关的那些。增加肌细胞在生理水平的机械应力后重新密封其膜的能力的治疗方法可以解决这两种机制，从而改善肌营养不良症病理学。我们最近发现，mitsuguimin 53（MG 53），肌肉特异性TRIM家族蛋白，是急性膜修复机制的重要组成部分。MG 53使细胞内囊泡向损伤部位的募集成核以形成膜补丁。我们发现，MG 53可以与dysferlin相互作用，以促进其膜修复功能，肌营养不良症中的一些膜修复缺陷与MG 53，小窝蛋白-3和dysferlin之间的相互作用改变有关。在本申请中提供的新数据中，我们发现许多细胞类型的急性损伤导致磷脂酰丝氨酸（PS）信号暴露于细胞外空间，可以通过纯化的重组人MG 53蛋白（rhMG 53）检测到，使rhMG 53定位于损伤部位并增加靶细胞修复膜损伤的能力。这些发现使我们假设：rhMG 53和天然MG 53可以结合流经膜破裂的PS，以增加细胞膜的膜修复能力。该作用将允许rhMG 53充当用于治疗肌营养不良症的治疗剂。我们将用两个具体的目标来检验这种可能性。目的1探讨rhMG 53在细胞膜重封中的作用机制。目的2将测试rhMG 53是否可以在DMD的忠实小鼠模型中提供治疗益处。我们的研究为理解细胞外MG 53在膜修复中的作用机制提供了重要的步骤，并有助于确定rhMG 53是否可以有效治疗肌营养不良症模型。rhMG 53增加非肌肉细胞中膜修复的能力表明，rhMG 53可以作为一种平台技术，可以靶向许多不同的疾病状态，其中受损的膜完整性和/或坏死细胞死亡导致潜在的病理学。

DESCRIPTION (provided by applicant): Duchenne muscular dystrophy (DMD) and other dystrophies arising from mutations in the dystrophin/dystroglycan complex produce pathology, at least in part, due to sarcolemmal membrane fragility. Several other forms of muscular dystrophy have been linked to defective membrane repair including those linked to mutations in caveolin-3 (Cav3) and dysferlin in human patients. A therapeutic approach to increase the capacity of muscle cells to reseal their membranes following physiological levels of mechanical stress could address both of these mechanisms leading to improvement of muscular dystrophy pathology. We recently discovered that mitsuguimin 53 (MG53), a muscle-specific TRIM-family protein, is an essential component of the acute membrane repair machinery. MG53 nucleates recruitment of intracellular vesicles to the injury site for membrane patch formation. We found that MG53 can interact with dysferlin to facilitate its membrane repair function, and some of the membrane repair defects in muscular dystrophy are associated with altered interaction between MG53, caveolin-3 and dysferlin. In new data presented in this application, we find that acute injury many cell types leads to exposure of a phosphatidylserine (PS) signal to the extracellular space that can be detected by purified recombinant human MG53 protein (rhMG53), allowing rhMG53 to locate to the injury sites and increase the capacity of targeted cells to repair membrane damage. These findings led us to hypothesize that: rhMG53 and native MG53 can bind to PS that flows through membrane disruptions to increase the membrane repair capacity of cell membranes. This action would allow rhMG53 to act as a therapeutic agent for the treatment of muscular dystrophy. We will test this possibility with two specific Aims. Aim 1 will establish the mechanism(s) contribute to the extracellular action of rhMG53 in membrane resealing. Aim 2 will test if rhMG53 can provide therapeutic benefit in a faithful mouse model of DMD. Our studies here provide important steps forward in understanding the mechanisms of extracellular MG53 action in membrane repair and can help to establish if rhMG53 could effectively treat a model of muscular dystrophy. The ability for rhMG53 to increase membrane repair in non-muscle cells suggests that rhMG53 may act as a platform technology that could target a number of different disease states where compromised membrane integrity and/or necrotic cell death contribute to the underlying pathology.