Structure and function of muscle

说明(申请人提供)：肌肉对循环系统、泌尿生殖系统、呼吸系统和消化系统的功能是必不可少的。虽然人们对肌球蛋白的力量生成能力了解很多，但对肌细胞内收缩机制是如何组织的，以及在收缩周期中它是如何稳定的，人们知之甚少。肌动蛋白细丝锚定的位置代表了收缩装置的组织、整合和拴系的关键位置。肌动蛋白的交联蛋白α-肌动蛋白集中在肌肉中的肌动蛋白锚定部位。我们已经确定了两个LIM结构域蛋白家族的成员，即富含半胱氨酸的蛋白(CRP)家族和ALP-Enigma家族的成员作为α-肌动蛋白结合伙伴。我们已经证明，这些蛋白质在肌肉中丰富，它们与肌动蛋白细丝锚定位置的α-肌动蛋白共定位。在这里，我们建议定义这些蛋白质对肌肉细胞结构和功能做出贡献的机制。通过对我们产生的功能缺失突变的分析，我们将确定这些蛋白质对正常肌肉结构和功能的贡献。我们将研究这些遗传改变对肌肉中肌动蛋白锚定部位的超微结构组织和分子结构的影响，包括Z盘状突起、致密小体和细胞粘附区。我们将鉴定与CRP和ALPEnigma复杂的蛋白质，以便更全面地了解它们的分子作用机制。肌肉中肌动蛋白细丝锚定的区域被认为在肌肉稳定性中起着关键作用，这些区域可以作为结构传感器来监测收缩机械的完整性和功能。在人类中，肌动蛋白锚定部位成分的缺乏与心肌病有关。因此，我们的结果将有助于理解肌肉的正常功能以及肌肉病理的各个方面。

DESCRIPTION (provided by applicant): Muscle is essential for the function of the circulatory, urogenital, respiratory, and digestive systems. Although much is understood about the force-generating capacity of acto-myosin, little is known about how the contractile machinery is organized within muscle cells and about how it is stabilized during contraction cycles. Sites of actin filament anchorage represent key sites for organization, integration, and tethering of the contractile apparatus. The actin crosslinking protein, a-actinin, is concentrated at actin anchorage sites in muscle. We have identified members of two families of LIM domain proteins, the Cysteine-Rich Protein (CRP) family and the ALP-Enigma family as a-actinin binding partners. We have demonstrated that these proteins are enriched in muscle where they co-localize with a-actinin at actin filament anchorage sites. Here we propose to define the mechanisms by which these proteins contribute to muscle cytoarchitecture and function. By analysis of lossof-function mutations that we have generated, we will defme the contributions of these proteins to normal muscle structure and function. We will examine the consequences of these genetic alterations for the ultrastructural organization and molecular architecture of actin anchorage sites in muscle, including Z-discs, dense bodies, and regions of cell adhesion. We will identify the proteins that complex with CRP and ALPEnigma in order to gain a more comprehensive view of their molecular mechanisms of action. Regions of actin filament anchorage in muscle are proposed to play a critical role in muscle stability, and these areas may serve as architectural sensors that monitor the integrity and function of the contractile machinery. In humans, deficiencies in components of actin-anchorage sites are associated with cardiomyopathies. Therefore, our results will contribute to an understanding of both normal muscle function as well as aspects of muscle pathology.