PHYSIOLOGY OF RESPIRATORY MUSCLE MIRCO MECHANICS

描述：我们建议调查力传递的机制， 骨骼肌特别是，我们将研究结蛋白的贡献， 和肌营养不良蛋白，膜细胞骨架的细胞内成分， 膜受体α-7-整联蛋白和细胞外分子merosin， 膈肌的力量传递。结蛋白缺乏导致 结蛋白病，一种罕见的疾病。肌营养不良蛋白、肌球蛋白或 α-7-整联蛋白导致各种形式的肌营养不良， 常见疾病。缺乏这些蛋白质中的任何一种都会导致骨骼肌 退化，慢性吸气肌无力，最终呼吸 导致呼吸衰竭并最终死亡。的 与大多数其他骨骼肌不同，隔膜在体内是双轴加载的。 也就是说，横膈膜承受着沿着肌纤维和横向于肌纤维的负荷。 收缩活动中的纤维。这个应用程序是一个初步的第一步 对理解膈肌的机械行为在 细胞水平。我们的中心假设是， 横膈膜受横向纤维负荷的调节，并由连杆调节 跨膜蛋白的特异性细胞内和细胞外成员 网络这一假设将通过研究自发的和工程化的 突变小鼠品系;使用缺失跨膜关键元件的品系 蛋白质网络，我们将测试双轴力学性能的响应 的隔膜和后肢肌肉缺乏这些蛋白质。的 这项研究计划的长期目标是了解肌肉力量 在蛋白质水平上的骨骼肌传输，并建立详细的 正常骨骼肌的机械耦合模型，解释了 力从细胞骨架传递到细胞外的机制 矩阵该项目的具体目标是确定被动机械 小鼠膈肌的性质及其对收缩功能的影响 并评估细胞内、跨膜和细胞外 元件上的双向力在膜片上传递。使用 应用于整个膜片的电子显微镜和双轴加载技术 和四肢骨骼肌在体外，我们将测试以下假设， 组织和肌节水平：（1）横向应力介导力 在组织和肌节水平的正常隔膜中的传输， 隔膜的被动和收缩特性都被 横向应力的存在;（2）跨膜的细胞内成员 蛋白质网络，结蛋白和肌营养不良蛋白，是必不可少的整合横向 和纵向机械性能的隔膜，和强度， 确定肌原纤维和质膜之间的机械连接 主要通过这些蛋白质;和（3）肌原纤维之间的机械偶联 细胞外基质对力的沿着和横向传递至关重要 正常骨骼肌中的纤维，力的传递受到影响 α-7-整联蛋白或merosin的缺失。这些目标针对 力传递由特定细胞骨架介导的机制 和骨骼肌中的细胞外蛋白质。

DESCRIPTION: We propose to investigate the mechanisms of force transmission in skeletal muscles. In particular, we will investigate the contribution of desmin and dystrophin, intracellular components of the membrane cytoskeleton, the membrane receptor alpha-7-integrin, and the extracellular molecular merosin to force transmission in diaphragm muscle. Desmin deficiency leads to desminopathy, a rare disease. Deficiencies of dystrophin, merosin, or alpha-7-integrin lead to various form of muscular dystrophy, which are more common diseases. Lack of any of these proteins causes skeletal muscle degeneration, chronic inspiratory muscle weakness, and ultimately respiratory insufficiency that leads to respiratory failure and eventually death. The diaphragm, unlike most other skeletal muscles, is loaded biaxially in vivo. That is the diaphragm experiences loads along muscle fibers and transverse to fibers during contractile activity. This application is an initial first step towards understanding the mechanical behavior of diaphragm muscle at the cellular level. Our central hypothesis is that force transmission in the diaphragm is modulated by transverse fiber loading and mediated by the linkage of specific intra- and extracellular members of the transmembrane protein network. This hypothesis will be tested by studying spontaneous and engineered mutant mouse strains; using strains missing key elements of the transmembrane protein network, we will test the response of the biaxial mechanical properties of the diaphragm and hindlimb muscles to the absence of these proteins. The long term goals of this research program are to understand muscle force transmission in skeletal muscles at the protein level and build a detailed model of mechanical coupling in normal skeletal muscles that explains the mechanism(s) by which force is transmitted from cytoskeleton to extracellular matrix. The specific aims of this project are to determine passive mechanical properties of the mouse diaphragm and their influence on contractile function and to evaluate the role of intracellular, transmembrane, and extracellular elements on the biaxial transmission of force in the diaphragm. Using a electron microscopy and biaxial loading technique applied to whole diaphragm and limb skeletal muscles in vitro, we will test the following hypotheses at both tissue and sarcomere levels: (1) transverse stress mediates force transmission in the normal diaphragm at both tissue and at sarcomere levels, and both passive and contractile properties of the diaphragm are altered by the presence of transverse stress; (2) intracellular members of the transmembrane protein network, desmin and dystrophin, are essential in integrating transverse and longitudinal mechanical properties of the diaphragm, and the strength of the mechanical linkage between myofibrils and the plasma membrane is determined primarily by these proteins; and (3) the mechanical coupling between myofibrils and extracellular matrix is crucial to force transmission along and transverse to the fibers in normal skeletal muscles, and force transmission is compromised by loss of either alpha-7-integrin or merosin. These aims address the mechanism(s) by which force transmission is mediated by specific cytoskeletal and extracellular proteins in skeletal muscles.