Myocyte Shape in Myofibril Patterning and Contraction

描述(由申请人提供)：开发治疗心力衰竭的新治疗策略取决于确定心肌细胞内易受治疗性利用的分子信号通路。到目前为止，我们对心肌细胞收缩的调节机制的了解仅限于Frank-Starling定律、Bowditch效应和细胞内信号通路。然而，肌细胞的形状可以作为一个独特的信号，能够激活信号通路、遗传程序和肌原纤维模式。本提案将阐述心肌细胞形态在肌原纤维形成和收缩中的作用。我们认为，心肌细胞形状的改变可以增强细胞骨架结构和肌原纤维模式，从而调节收缩性能。为了验证这一假设，我们将探索肌细胞如何响应细胞外基质蛋白微图案岛的几何形状控制的肌细胞形状和结构的变化。初步结果表明，肌细胞的铺展程度和肌细胞的几何形状可以调节肌节的空间分布以及肌节的串、并联束。在具体目标1中，使用多个系列的几何孤岛来特定地改变投射的心肌细胞面积、周长、纵横比和角度提示，我们将识别控制这种组装的几何参数。我们将确定细胞骨架如何自我组装，肌原纤维如何响应这些信号而形成图案，以及它们的组装和图案形成速度是如何受到影响的。在特定的目标2中，我们将观察心肌细胞形状如何影响收缩强度、收缩速度和松弛。具体目标3将研究在鲍迪奇效应中肌细胞形状、细胞骨架结构和肌原纤维构型的作用。特定目的4研究小Rho GTP酶Rac和Rho在肌原纤维形成中的作用。这些实验将阐明心脏组织微环境在心脏形态发生和发病机制中的作用。

DESCRIPTION (provided by applicant): Developing new therapeutic strategies for treating heart failure is dependent upon identifying molecular signaling pathways within the cardiac myocyte that are vulnerable to therapeutic exploitation. To date, our understanding of the regulators of myocyte contractility has been limited to the Frank-Starling law, the Bowditch effect, and intracellular signaling pathways. Myocyte shape, however, may serve as a distinct signal, capable of activating signaling pathways, genetic programs, and myofibrillar patterning. This proposal will address the role of myocyte shape in myofibrillogenesis and contractility. We propose that changes in myocyte shape can potentiate cytoskeletal architectures and myofibrillar patterning that can regulate contractile performance. To test this hypothesis, we will probe how myocytes respond to changes in myocyte shape and structure as controlled by the geometry of micropatterned islands of extracellular matrix proteins. Preliminary results suggest that the degree of myocyte spreading and the myocyte geometry can regulate the spatial distribution of sarcomeres and their serial and parallel bundling. In Specific Aim 1, using multiple series of geometric islands to specifically vary projected myocyte area, perimeter, aspect ratio, and angular cues we will identify geometric parameters controlling this assembly. We will determine how the cytoskeleton self assembles and how myofibrils pattern in response to these signals and how their rates of assembly and patterning are affected. In Specific Aim 2, we will look at how myocyte shape affects contractile strength, rate, and relaxation. Specific Aim 3 will examine the role of myocyte shape, cytoskeletal architecture, and myofibrillar patterning in the Bowditch effect. Specific Aim 4 examines the role of the small Rho GTPases Rac and Rho on myofibrillogenesis. These experiments will shed light on the role of the cardiac tissue microenvironment on cardiac morphogenesis and pathogenesis.