Therapeutic Potentential of Epsilon-Sarcoglycan in LGMD Type 2D

描述(申请人提供)：该项目的长期目标是设计一种治疗2D常染色体隐性遗传性肢带型肌营养不良症(LGMD-2D)的方法，这种病是由于肌聚糖基因(SGCA)的异常引起的，主要影响肢体和腰带肌肉，导致进行性肌肉纤维坏死和无力，α-肌聚糖与β-、γ-和β-肌聚糖相互作用形成一种亚复合体，从而增加营养不良蛋白糖蛋白复合体(DGC)的整体稳定性。Epsilon-SarcoGan是一种普遍表达的肌肉特异性α-肌聚糖的同源物，有43%的同源性和相似的蛋白质结构。早在E8.5天的小鼠胚胎中就检测到了epsilon-肌聚糖的表达，而在E15检测到α-肌聚糖之前，初步数据显示在肌肉再生过程中检测到的增加，表明epsilon-肌聚糖是α-肌聚糖的胚胎或发育形式。本项目的重点是探索上调表观肌聚糖水平治疗LGMD-2D的治疗潜力。第一个目标假设，在DGC中，epsilon-肌聚糖的表达增加将取代α-肌聚糖。通过将epsilon-肌聚糖定向过表达到肌肉的转基因小鼠的特征将验证这一假说。第二个目标假设，增加的epsilon-肌聚糖的表达将补偿异常的α-肌聚糖，以防止肌营养不良的发生。对Sgca基因缺失的小鼠过度表达epsilon-肌聚糖的分析将检验这一假设。最终目的假设，在α-肌聚糖缺乏症中，增加和持续的epsilon-肌聚糖表达将防止进一步的肌肉病理，并修复原发的膜缺陷，以允许正常的肌肉功能。成年SGCA基因缺失的小鼠将肌肉注射rAAV1-epsilon-肌聚糖并进行分析。本项目将研究在预防和治疗α-肌聚糖缺乏症的肌营养不良症中，增加表型肌聚糖水平的功能和生理后果。这些实验的总体结果将为LGMD-2D患者增加表观-肌聚糖表达以补偿(-肌聚糖)的可能性奠定基础。专注于一种内源性蛋白，如epsilon-肌聚糖，将绕过任何获得性治疗性免疫反应，并为旨在上调epsilon-肌聚糖的治疗和药物治疗的新靶点提供平台。

DESCRIPTION (provided by applicant): The long-term goal of this project is to design a therapy for autosomal recessive limb-girdle muscular dystrophy type 2D (LGMD-2D), which is due to aberrations in the (-sarcoglycan gene (Sgca), and affects mainly limb and girdle muscles to lead to progressive muscle fiber necrosis and weakness, Alpha-Sarcoglycan interacts with beta-, gamma-, and delta-sarcoglycan to form a subcomplex that increases the overall stability of the dystrophin-glycoprotein complex (DGC). Epsilon-Sarcoglycan is a ubiquitously expressed homologue of the muscle-specific alpha- sarcoglycan, sharing 43% identity and a similar protein structure. Epsilon-Sarcoglycan expression is detected as early as day E8.5 in mouse embryos before the detection of alpha-sarcoglycan at E15, and preliminary data shows increased detection during muscle regeneration suggesting that epsilon-sarcoglycan is embryonic or developmental form of alpha-sarcoglycan. This project focuses on exploring the therapeutic potential of upregulating epsilon-sarcoglycan levels for the treatment of LGMD-2D. The First Aim hypothesizes that increased expression of epsilon-sarcoglycan will replace alpha-sarcoglycan within the DGC. Characterization of transgenic mice with targeted overexpression of epsilon-sarcoglycan to muscle will test this hypothesis. The Second Aim hypothesizes that increased expression of epsilon-sarcoglycan will compensate for an aberrant alpha-sarcoglycan to prevent the onset of muscular dystrophy. Analysis of Sgca-null mice overexpressing epsilon-sarcoglycan will test this hypothesis. The Final Aim hypothesizes that increased and sustained epsilon-sarcoglycan expression in alpha-sarcoglycan deficiency will prevent further muscle pathology and repair the primary membrane defect to allow for normal muscle function. Adult Sgca-null mice will be intramuscularly injected with rAAVl epsilon-sarcoglycan and analyzed. This project will investigate the functional and physiological consequences of increased levels of epsilon-sarcoglycan to prevent and treat muscular dystrophy in alpha-sarcoglycan deficiency. The overall results of these experiments will develop the possibility of increased epsilon-sarcoglycan expression to compensate for (-sarcoglycan in LGMD-2D patients. Focusing on an endogenous protein like epsilon-sarcoglycan will bypass any acquired therapeutic immune response, and provides a platform for new targets for therapy and drug treatments aimed at up-regulating epsilon-sarcoglycan