Chemical and Physical Control of Ectopic Contractile Rings

生命系统最迷人和最重要的特性之一是它们科普物理损伤的能力。这种特性在单细胞和多细胞系统中都很明显，并且不仅在许多不同的动物门中广泛保守，而且在植物中也是如此。由于其明显的临床重要性，多细胞伤口愈合长期以来一直是密切关注的主题。 相反，直到最近，单细胞中质膜创伤的修复一直被忽视。至少有两种机制已经被描述：一个非常快速的膜融合事件，提供了一个即时的块涌入的离子，否则会杀死细胞，和一个较慢的收缩反应，其中一个圆周环的肌动蛋白丝和肌球蛋白-2组装周围的伤口，然后关闭。本项目的主要目标是表征调节异位收缩环组装和闭合的机制。使用非洲爪蟾卵母细胞作为模型系统，将采用物理，显微镜和重组DNA为基础的方法相结合，以测试细胞张力，局部增加rho类GTdR活性，和细胞内游离钙之间的关系，在招聘肌动蛋白丝和肌球蛋白-2伤口边缘。除了提供与质膜损伤修复的基本生物学过程直接相关的信息外，拟议的研究有可能深入了解类似异位收缩环组装和闭合的过程，如动物细胞胞质分裂。

One of the most fascinating and important properties of living systems is their ability to cope with physical damage. This property is manifest in both single cells and multicellular systems, and is broadly conserved not only in a number of different animal phyla, but in plants as well. Because of its obvious clinical importance, multicellular wound healing has long been the subject of intense scrutiny. In contrast, repair of plasma membrane wounds in single cells has been overlooked until relatively recently. At least two mechanisms have been described: an extremely rapid membrane fusion event that provides an immediate block to the inrush of ions that would otherwise kill the cell, and a slower contractile response in which a circumferential ring of actin filaments and myosin-2 assembles around the wound and then closes. The primary goal of this project is to characterize the mechanisms that regulate assembly and closure of this ectopic contractile ring. Using Xenopus oocytes as a model system, a combination of physical, microscopic, and recombinant DNA-based approaches will be employed to test relationships between cell tension, local increases in rho class GTPase activity, and intracellular free calcium, in the recruitment of actin filaments and myosin-2 to the wound border. In addition to providing information directly relevant to the basic biological process of repair of damage to the plasma membrane, the proposed studies have the potential to provide insights into processes which resemble ectopic contractile ring assembly and closure, such as animal cell cytokinesis.