Mechanisms of couplon-linked skeletal muscle myopathies

骨骼肌横小管中的L型钙通道（CaV1.1）， 肌浆网（SR）和连接SR（jSR）管腔中的钙螯合蛋白（Casq 1）是 一种称为耦合子的大分子复合物，其调节兴奋-收缩偶联（ECC）。突变 RyR 1、CaV1.1和Casq 1是具有重叠病理特征的人类肌病的基础。但不包括 丹曲林用于恶性高热，没有FDA批准的用于这些肌病中的任何一种的干预。小鼠 具有突变CaV1.1（E1014 K）、RyR 1（I4895 T）和Casq 1（D244 G）的患者发生肌病， 随着年龄的增长，他们的肌肉显示Casq 1定位错误和持续的ER应激。此应用程序旨在 阐明CaMKII依赖性途径中突变相关改变导致ER的机制 压力/普遍定期审议和肌肉疾病。我们将检验一般假设，即couplon肌病的相似性 由不同偶联体蛋白中的突变引起的突变是由于高度合作的双向功能偶联 CaV1.1、CaMKII、RyR 1和Casq 1之间的差异。我们的目标是：1.定义CaV1.1功能状态改变的作用 Couplon肌病中的转换和CaMKII激活。2.量化耦合疾病相关的影响 RyR 1磷酸化突变以及磷酸化介导的对CaV1.1功能和Casq 1的影响 保留在jSR中。3.明确Casq 1定位错误和ER应激在couplon肌病中的作用。我们将 还测试了4PBA的能力，它减轻了ER应激，以改善肌肉功能，在肌病引起的， 偶联体蛋白的突变。

The skeletal muscle L-type Ca2+ channel (CaV1.1) in the transverse tubules, the ryanodine receptor (RyR1) in the sarcoplasmic reticulum (SR), and calsequestrin (Casq1) in the lumen of junctional SR (jSR) are key components of a macromolecular complex termed the couplon which regulates excitation-contraction coupling (ECC). Mutations in RyR1, CaV1.1, and Casq1 underlie human myopathies with overlapping pathological features. With the exception of dantrolene for malignant hyperthermia, there are no FDA approved interventions for any of these myopathies. Mice with a mutations CaV1.1 (E1014K), RyR1 (I4895T) and Casq1 (D244G) develop myopathies that increase in severity with age and their muscles display Casq1 mislocalization and persistent ER stress. This application is designed to elucidate the mechanisms by which mutation-associated alterations in a CaMKII-dependent pathway lead to ER stress/UPR and muscle disease. We will test the general hypothesis that the similarities in couplon myopathies arising from mutations in different couplon proteins are due to highly cooperative, bidirectional functional coupling between CaV1.1, CaMKII, RyR1 and Casq1. Our aims are to: 1. Define the roles of altered CaV1.1 functional state transitions and CaMKII activation in couplon myopathies. 2. Quantify the effects of couplon disease-associated mutations on RyR1 phosphorylation and the phosphorylation-mediated effects on CaV1.1 function and Casq1 retention at the jSR. 3. Define the roles of Casq1 mislocalization and ER stress in the couplon myopathies. We will also test the ability of 4PBA, which alleviates ER stress, to improve muscle function in myopathies that arise from mutations in couplon proteins.