Calcium Regulation in the Progression of Muscular Dystrophy

杜氏肌营养不良症是一种常见的遗传性疾病，由肌营养不良蛋白内的突变引起 基因营养不良的表型可能不是直接由肌原纤维的改变引起的， 相反，它是一种破坏肌膜完整性的结构，通常赋予严格的控制， 细胞内Ca稳态，这导致细胞内Ca升高和最终的肌肉变性。 然而，导致细胞内钙水平升高的病理生理机制尚不清楚 我们最近的研究结果表明，与不受控制的钙火花活动有关的钙库操纵的钙进入（SOCE）可能 导致在营养不良肌肉中观察到的异常Ca内流。虽然SOCE激活的机制 钙不敏感磷脂酶A2是一种新型的磷脂酶， （iPLA2）是SOCE的重要介质。本课题的重点是验证一个假设，即异常Ca 火花活动作为SOCE的触发器，从而诱导哺乳动物骨骼肌中的营养不良级联反应， 肌肉通过涉及iPLA2介导的信号传导的途径。我们将通过三个具体目标来测试这一点： 目的1：在健康和营养不良的肌肉中建立诱导钙火花作为SOCE的触发器。我们将 利用多种方法测量SOCE以检查营养不良纤维中Ca内流的改变。 膜片钳测量和Oa内流的调节将提供对SR Ca释放的深入了解， 营养不良纤维中SOCE的激活。目的2：确定iPLA 2活性对心肌细胞中Ca内流的贡献。 肌肉萎缩症我们将使用免疫组织化学方法研究营养不良肌肉中iPLA 2功能的改变特征。 各种体外分子和药理学方法。目标3：阐明SOCE是否有助于 骨骼肌营养不良级联反应。由于无法评估营养不良表型的变化， 骨骼肌翼将调节营养不良动物中SOCE，并测定营养不良动物中 表型

Duclienne muscular dystrophy is a common genetic disorder resulting from mutations within the dystrophin gene. It is likely that the dystrophic phenotype does not result directly from alteration to the myofibrillar Structures, rather it is a disruption of sarcolemmal membrane integrity that nomnally confers tight control of intracellular Ca homeostasis, which leads to elevated intracellular Ca and eventual muscle degeneration. The pathophysiological mechanism responsible for elevation of intracellular Ca levels is not dear, however our recent findings suggest that store-operated Ca entry (SOCE) linked to uncontrolled Ca spark activity may contribute to the aberrant Ca influx observed in dystrophic muscle. While the mechanism of SOCE activation is still a matter of intensive study, it has been recently detemnined that the Ca insensitive phospholipase A2 (iPLA2) is an important mediator of SOCE. The focus of this project is to test the hypothesis that aben-ant Ca spark activity acts as a trigger for SOCE and thus induces a dystrophic cascade in mammalian skeletal muscle through a pathway that involves iPLA2 mediated signaling. We will test this with three specific aims: Aim 1; To establish induced Ca sparks as a trigger for SOCE in healthy and dystrophic muscle. We will utilize multiple methods for measurement of SOCE to examine alteration to Ca entry in dystrophic fiber. Patch-clamp measurement and modulation of Oa influx will provide insight into SR Ca release and the activation of SOCE in dystrophic fibers. Aim 2: Detemiine the contribution of iPLA2 activity to Ca influx in muscular dystrophy. We will examine the altered characteristics of iPLA2 function in dystrophic muscle using various in vitro molecular and pharmacological methods. Aim 3: To elucidate if SOCE facilitates the dystrophic cascade in skeletal muscle. Due to the inability to assess changes in the dystrophic phenotype in skeletal muscle we wili modulate SOCE in dystrophic animals and assay changes in dystrophic phenotypes.