Study of Cell Adhesion through an Analysis of Myosin 7

身体抵抗感染的第一道防线是循环的白色血细胞， 检测并响应组织损伤。这些细胞迅速向受伤部位移动 利用变形虫类型的运动。这一运动的特点是形成了 细胞和周围基质之间广泛分布的低亲和力接触。的 由白细胞产生的阿米巴样粘连由许多相同的 组分作为组织紧密、亲和力高的粘附物，通过缓慢移动形成 成纤维细胞（局灶性接触），但这些分子的组织和调节 在变形虫细胞中是不同的。确定共享的不同机制 与成纤维细胞相比，变形细胞中使用粘附分子是关键， 了解细胞如何快速迁移。 细胞粘附机制提供了细胞外基质之间的动态联系 受体和肌动蛋白细胞骨架在整个进化过程中一直是保守的。一个 一种高度保守的非常规肌球蛋白，肌球蛋白VII（M7）， 在网骨阿米巴中发现了阿米巴样粘连。这个目标 项目是定义M7阿米巴粘附的作用。第一个问题是 阐述了M7是如何靶向粘附部位的，这是理解M7的关键一步。 这种马达蛋白和细胞粘附机制之间的关系。的 保守的M7尾部结构域对M7定位、膜动力学的贡献 和细胞粘附将被系统地研究。关键领域将是 用作探针来识别结合伴侣（最有可能是其他粘附分子或 监管机构）。下一个问题是M7运动活动是否需要它在 变形虫样粘连M7可能通过被动连接粘附参与粘附 细胞骨架的组成部分，或者它可能需要在细胞骨架的部位产生张力。 粘连表达M7运动突变体（强或弱肌动蛋白结合）的细胞将 表征以确定M7与肌动蛋白相互作用的循环是否是其 在阿米巴样粘连中的作用。还将对M7的运动特性进行体外分析。 以确定其是否具有用作锚或运输工具的潜力 电机这项研究的结果将提供基本的新见解的分子基础， 阿米巴样粘附以及肌球蛋白如何促成这种关键类型的粘附， 促进细胞快速迁移。

The body's first line of defense against infection is the circulating white blood cells that detect and respond to tissue damage. These cells move rapidly towards the site of injury using an amoeboid type of motility. This movement is characterized by the formation of broadly distributed, low affinity contacts between the cell and surrounding substrate. The amoeboid adhesions generated by leukocytes are composed of many of the same components as the tightly organized, high affinity adhesions formed by slowly moving fibroblastic cells (focal contacts), but the organization and regulation of these molecules is distinct in amoeboid cells. Identifying the distinct mechanisms by which shared adhesion molecules are employed in amoeboid cells versus fibroblastic cells is key to understanding how rapid cell migration is achieved. The cell adhesion machinery that provides a dynamic link between extracellular matrix receptors and the actin cytoskeleton has been conserved throughout evolution. An unexpected role for a highly conserved unconventional myosin, myosin VII (M7), in amoeboid adhesion has been discovered in the amoeba Dictyostelium. The goal of this project is to define the role of M7 amoeboid adhesion. The first question that will be addressed is how M7 is targeted to adhesion sites, a critical step towards understanding the relationship between this motor protein and the cell adhesion machinery. The contribution of the conserved M7 tail domains to M7 localization, membrane dynamics and cellular adhesion will be systematically investigated. Essential domains will then be used as probes to identify binding partners (most likely other adhesion molecules or regulators). The next question is whether M7 motor activity is required for its role in amoeboid adhesion. M7 could participate in adhesion by passively linking adhesion components to the cytoskeleton or it could be required to generate tension at sites of adhesion. Cells expressing M7 motor mutants (either strong or weak actin binding) will be characterized to determine if cycles of M7 interaction with actin are necessary for its role in amoeboid adhesion. An in vitro analysis of the motor properties of M7 will also be performed to determine if it has the potential to function as an anchor or a transport motor. The results of this study will provide basic new insights into the molecular basis of amoeboid adhesion and how a myosin contributes to this critical type of adhesion to promote rapid cell migration.