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依赖于鉴定心肌细胞内易受治疗利用的分子信号传导途径。迄今为止，我们对肌细胞收缩性调节因子的理解仅限于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图案。这项建议将解决肌细胞形状在肌原纤维形成和收缩性中的作用。我们认为，肌细胞形状的变化可以增强细胞骨架结构和肌原纤维图案，可以调节收缩性能。为了验证这一假设，我们将探讨肌细胞如何响应肌细胞形状和结构的变化，由细胞外基质蛋白的微图案岛的几何形状控制。初步结果表明，肌细胞的伸展程度和肌细胞的几何形状可以调节肌节的空间分布和它们的串行和并行捆绑。在特定目标1中，使用多个系列的几何岛来具体改变投影的肌细胞面积、周长、纵横比和角度线索，我们将识别控制该组装的几何参数。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，以及它们的组装和图案化速率如何受到影响。在特定目标2中，我们将研究肌细胞形状如何影响收缩强度、速率和舒张。具体目标3将研究肌细胞形状，细胞骨架结构和肌原纤维模式在鲍迪奇效应中的作用。具体目标4检查小Rho GTP酶Rac和Rho对肌原纤维发生的作用。这些实验将阐明心脏组织微环境对心脏形态发生和发病机制的作用。

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.