Epsilon-sarcoglycan in LGMD Type 2D

描述(由申请人提供)：母项目的长期目标是探索上调5-肌糖水平治疗二维型肢体带状肌营养不良症(LGMD2D)的治疗潜力。1-肌聚糖基因的突变导致LGMD2D，并导致进行性肌肉纤维坏死和无力。我们发现，在LGMD-2D小鼠模型中，5-肌聚糖能够挽救1-肌聚糖缺乏症并预防肌营养不良。尽管表现出正常的肌肉功能，但由于肌膜nNOS信号的缺乏，这些被拯救的小鼠对轻度运动产生了夸大的疲劳反应。因此，像我们的救援鼠一样，我们发现这种特殊形式的疲劳可以发生在没有肌肉病理的小鼠模型中，这表明肌膜nNOS信号的缺陷可能是没有躯体疾病的人类这种形式疲劳的原因。值得注意的是，我们发现PDE5A抑制剂的药物治疗通过增强活跃肌肉的一氧化氮信号来缓解这种形式的疲劳。此外，我们还发现，这种疗法还提高了运动耐力，减少了营养不良小鼠因运动引起的肌肉浮肿。这项竞争性修订的重点是探索药物治疗策略，包括参与运动的途径，以防止这种形式的疲劳以及防止运动引起的小鼠模型肌肉水肿。第一个目标假设长期的PDE5A抑制剂治疗将改善我们的小鼠模型的日常活动。使用PDE5A抑制剂的长期衍生物治疗的营养不良和救援性小鼠模型的纵向特征将检验这一假设。第二个目标假设，绕过一氧化氮依赖途径是增加运动诱导信号的另一种选择。对使用一氧化氮非依赖性鸟苷环化酶激活剂以及可溶性鸟苷环化酶和PDE5A基因缺失处理的小鼠模型的分析将检验这一假设。最终目标假设抗炎治疗将减少营养不良小鼠模型的病理，但也增加活动和减少运动诱导的肌肉浮肿。对用不同消炎药治疗的小鼠模型的分析将检验这一假设。这些实验的总体结果将有助于将其发展为与基因治疗的协同治疗，并为健康个体的运动性疲劳和浮肿提供见解。 公共卫生相关性：这项研究将有助于NIAMS在解决运动性疲劳和肌肉水肿方面影响肌肉的生物医学研究的使命。这项拟议的研究还将有助于ARRA改善人类生活质量的使命，同时通过为该项目提供招聘机会以及为我们的科学家提供更多培训来刺激经济，以提高他们作为独立生物医学研究人员的市场能力，他们将建立自己的实验室。

DESCRIPTION (provided by applicant): The parent project long-term goal is to explore the therapeutic potential of up-regulating 5-sarcoglycan levels for the treatment of limb-girdle muscular dystrophy type 2D (LGMD2D). Mutations in the 1-sarcoglycan gene cause LGMD2D, and leads to progressive muscle fiber necrosis and weakness. We found that 5-sarcoglycan is able to rescue 1- sarcoglycan deficiency and prevent the muscular dystrophy in a mouse model for LGMD-2D. Despite displaying normal muscle function, these "rescued" mice experienced an exaggerated fatigue response to mild exercise due to deficient sarcolemmal nNOS signaling. Thus, like our rescue mouse, we found that this specific form of fatigue can occur in mouse models that do not have muscle pathology suggesting that deficient sarcolemmal nNOS signaling could be the cause of this form of fatigue in humans that do not have a somatic disease. Significantly, we found that pharmacological treatment with PDE5A inhibitors relieves this form of fatigue by enhancing the nitric oxide signaling from active muscle. In addition, we found that this treatment also improves exercise tolerance and reduces exercised-induced muscle edema in our dystrophic mice. This Competitive Revision focuses on exploring pharmacological treatment strategies encompassing pathways involved in exercise to prevent this form of fatigue as well as prevent exercise-induced muscle edema in our mouse models. The first aim hypothesizes that long-term PDE5A inhibitor treatment will improve the daily activity of our mouse models. Longitudinal characterization of dystrophic and rescue mouse models treated with long-term derivatives of PDE5A inhibitors will test this hypothesis. The second aim hypothesizes that bypassing the nitric oxide dependent pathway is an alternative to increasing exercise-induced signaling. Analysis of mouse models treated with nitric oxide-independent guanylate cyclase activators as well as genetic deletion of soluble guanylate cyclase and PDE5A will test this hypothesis. The final aim hypothesizes that anti-inflammatory treatment will decrease pathology in dystrophic mouse models but also increase activity and reduce exercise-induced muscle edema. Analysis of mouse models treated with various anti-inflammatories will test this hypothesis. The overall results of these experiments will help develop as a synergistic treatment with gene therapy as well as provide insights into exercise-induced fatigue and edema in healthy individuals. PUBLIC HEALTH RELEVANCE: This research will contribute to the mission of NIAMS for biomedical research affecting muscles in terms of addressing exercise-induced fatigue and muscle edema. This proposed research will also contribute to the mission of the ARRA in improving the quality of human life while stimulating the economy by providing hiring opportunities for the project as well as providing increased training for our scientists to improve their marketability as independent biomedical researchers who will start their own laboratories.