PHYSIOLOGY OF RESPIRATORY MUSCLE MIRCO MECHANICS

描述：我们建议研究力传递的机制 骨骼肌。特别是，我们将调查desmin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-整合素和胞外分子Merosin 横隔肌中的力传递。Desmin缺乏导致 脱脂症，一种罕见的疾病。肌营养不良蛋白、麦角蛋白或 α-7-整合素导致各种形式的肌营养不良，其中更多 常见病。缺乏这些蛋白质中的任何一种都会导致骨骼肌 变性，慢性吸气肌无力，最终是呼吸系统 导致呼吸衰竭并最终死亡的功能不全。这个 与大多数其他骨骼肌不同，横隔膜在体内是双向加载的。 也就是说，横隔膜承受着沿肌肉纤维和横跨 收缩活动中的纤维。这个应用程序是第一步 了解横隔肌的力学行为 细胞水平。我们的中心假设是力在人体内的传递 膜片由横向光纤负载调制，并由连杆调节 跨膜蛋白的特定胞内和胞外成员 网络。这一假设将通过研究自发的和工程的来检验 突变的小鼠品系；使用缺少跨膜关键元件的品系 蛋白质网络，我们将测试响应的双轴力学性能 横隔肌和后肢肌肉对这些蛋白质的缺乏。这个 这项研究计划的长期目标是了解肌肉力量 在骨骼肌蛋白质水平上的传递和构建详细的 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(S) 矩阵。该项目的具体目标是确定被动机械 小鼠横隔膜的特性及其对收缩功能的影响 并评估细胞内、跨膜和细胞外的作用 元件上的力在膜片上双向传递。使用 电子显微镜和双轴加载技术在全横隔膜上的应用 和四肢骨骼肌的体外实验，我们将在 组织和肌节水平：(1)横向应力介导力 在正常横隔膜的组织和肌节水平上的传播， 并且隔膜的被动和收缩属性都通过 横向应力的存在；(2)跨膜的细胞内成员 蛋白网络，结蛋白和肌营养不良蛋白，是整合横向的必不可少的 和横隔膜的纵向机械性能，以及强度 确定了肌原纤维和质膜之间的机械连接。 主要通过这些蛋白质；以及(3)肌原纤维之间的机械耦合 细胞外基质对力的纵向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 通过丢失α-7-整合素或Merosin。这些目标解决了 特定细胞骨架介导力传递的机制(S) 和骨骼肌中的胞外蛋白。

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.