Dynamics and regulation of actomyosin contractility in the C. elegans embryo

描述（由申请人提供）：本研究的主要目的是了解控制非肌肉细胞中肌动球蛋白收缩性的基本原理，使用C。elegans作为一个模型系统。与骨骼肌收缩不同，在骨骼肌收缩中，力是由肌动蛋白丝和肌球蛋白马达的稳定的几乎晶体阵列产生的，非肌肉细胞的收缩是马达和细丝之间的分布式局部力产生相互作用的全局结果，这些马达和细丝在相互作用时快速组装，移动和分解。了解有组织的细胞尺度收缩行为如何从这些局部相互作用中产生，以及个体参与者的局部调节如何“调整”同一系统以产生不同的行为，对于了解细胞如何在正常发育和生理过程中调节收缩性以及疾病中如何失调至关重要。我们将解决这些挑战的背景下，一个基本的和广泛使用的模式的收缩性-称为局灶性收缩性-其中的周期性组装，收缩和拆卸的收缩网络驱动的细胞表面的瞬时变形，纠正产生细胞形状变化，皮质流动和组织变形。梭线虫胚胎提供了一个独特的易处理的机会，研究局灶性收缩在单个大细胞的表面使用发达的工具，分子遗传操作，转基因，和高分辨率定量光学显微镜。我们将使用定量成像、实验操作和预测性计算机模拟的紧密集成组合来提出以下问题：1）局灶性收缩循环如何工作？也就是说，是什么控制了病灶收缩的开始和终止？ 2)如何通过调节局部肌球蛋白活性来调节局部收缩性，以及肌球蛋白和肌动蛋白丝组装和分解的局部动力学？ 3)基于我们对肌动蛋白丝、肌球蛋白、交联剂及其关键调节剂的性质和相互作用的了解，详细的计算机模拟能否再现局灶性收缩及其调节的宏观动力学，并揭示其基本原理？鉴于广泛的保护分子参与肌动球蛋白收缩，我们的工作将有直接的相关性，以了解收缩在许多其他情况下，无论是在健康和疾病。

DESCRIPTION (provided by applicant): The broad goal of this study is to understand the basic principles that govern actomyosin contractility in non-muscle cells, using C. elegans as a model system. Unlike in skeletal muscle contraction, where force is produced by stable almost crystalline arrays of actin filaments and myosin motors, contractility in non-muscle cells is the global consequence of distributed local force-generating interactions among motors and filaments that rapidly assemble, move and dissemble as they interact. Understanding how organized cell-scale contractile behaviors emerge from these local interactions, and how local regulation of the individual players "tunes" the same system to produce different behaviors, is fundamental to understanding how cells regulate contractility during normal development and physiology and how it is dysregulated in disease. We will address these challenges in the context of a fundamental and widely used mode of contractility - called focal contractility - in which the periodic assembly, contraction and disassembly of contractile networks drive transient deformations of the cell surface that are rectified to produce cell shape change, cortical flow and tissue deformation. The C. elegans embryo provides a uniquely tractable opportunity to study focal contractility at the surface of single large cells using well-developed tools for molecular genetic manipulation, transgenesis, and high-resolution quantitative light microscopy. We will use a tightly integrated combination of quantitative imaging, experimental manipulations, and predictive computer simulations to ask the following questions: 1) How does the focal contractility cycle work? i.e. what governs the initiation and termination of focal contractions? 2) How is focal contractility regulated by tuning local myosin activity, and the local kinetics of myosin and actin filament assembly and disassembly? 3) Can detailed computer simulations, based on what we know about the properties of and interactions among actin filaments, myosin, crosslinkers and their key regulators, reproduce the macroscopic dynamics of focal contractility and its regulation and reveal the fundamental underlying principles? Given the extensive conservation of molecular players involved in actomyosin contractility, our work will have direct relevance to understanding contractility in many other contexts, both in health and disease.