The Role of Intermediate Filaments in Skeletal Muscle Injury and Disease

说明(申请人提供)：骨骼肌劳损，特别是由于拉长(“偏心”)收缩，是所有与运动有关的损伤的主要原因，其特征是立即丧失产生力量的能力。结构损伤本身并不能解释损伤的数量，而且对于涉及的潜在机制以及治疗干预措施可以在多大程度上影响这些机制，仍然没有明确的认识。然而，对肌膜和相关的细胞骨架蛋白，包括肌膜结构蛋白和中间丝(IP)的损害也涉及到。细胞骨架蛋白对骨骼肌健康的重要性被一个或多个这些蛋白质的遗传缺陷导致人类肌肉营养不良或肌病的事实所强调。本研究的目的是研究IPs细胞角蛋白19(K19)在骨骼肌中的作用。通过实验确定它们在肌肉中的缺失如何影响肌膜的组织、膜的稳定性、肌膜和肌浆网的钙流量以及收缩功能。这项拟议的研究将使用动物模型来检验这一普遍假设，即这些IP在细胞骨架的组织、正常的钙稳态以及最终肌肉功能和对损伤的抵抗力中发挥着不可或缺的作用。这一假设将使用功能、形态和生化方法进行验证，既有完整的肌肉，也有分离的单一肌纤维。我们会提出两个具体目标： 研究缺乏细胞角蛋白19的动物的肌肉生理、膜结构和损伤敏感性，以及 为了确定持续缺乏IP导致的比力降低和继发的轻度肌病是否与肌纤维钙处理的改变有关。 这些研究的结果应该有助于理解慢性肌肉疾病以及急性肌肉损伤的影响。他们还应该阐明肌肉疾病和肌肉损伤、治疗和恢复的一些共同的细胞和分子机制。

DESCRIPTION (provided by applicant): Skeletal muscle strains, particularly from lengthening ("eccentric") contractions, account for a majority of all sports-related injuries and are characterized by an immediate loss of the ability to produce force. Structural damage alone does not account for the amount of impairment, and there is still not a clear understanding of underlying mechanisms involved and to what extent they can be affected by therapeutic interventions. Damage to the sarcolemma and associated cytoskeletal proteins, including structural proteins of the sarcolemma and intermediate filaments (IPs), is involved, however. The significance of cytoskeletal proteins to the health of skeletal muscle is underscored by the fact that genetic defects in one or more of these proteins cause muscular dystrophies or myopathies in humans. The purpose of the proposed research is to examine the role that IPs cytokeratin 19 (K19) play in skeletal muscle. Experiments are proposed to determine how their absence in muscle affects sarcolemmal organization, membrane stability, sarcolemmal and sarcoplasmic reticulum calcium flux, and contractile function. The proposed research will use an animal model to test the general hypothesis that these IPs play an integral part in the organization of the cytoskeleton, normal calcium homeostasis, and ultimately, muscle function and resistance to injury. The hypothesis will be tested using functional, morphological, and biochemical methods, with both intact muscles and isolated single myofibers. Two specific aims will be addressed: To study the muscle physiology, membrane structure, and susceptibility to injury in animals lacking cytokeratin 19, and To determine whether the reduced specific force and mild myopathy secondary to the persistent absence of IPs is associated with alterations in the myofiber Ca2+ handling. The results from these studies should be helpful in understanding the effects of chronic muscular diseases as well as of acute muscle injuries. They should also elucidate some of the shared cellular and molecular mechanisms of muscle disease and of muscle injury, treatment, and recovery.