Role of Rac and Rac Effectors in Controlling Chemotaxis

描述(申请人提供)：趋化性在不同的疾病中起着核心作用 生物过程，包括癌细胞的转移，炎性 涉及中性粒细胞和巨噬细胞运动、神经迁移的反应 棘细胞、胚胎形态发生和网柄蕨类的聚集。这个 控制真核细胞趋化性的潜在过程是高度 Dictyostelius与人类之间的保守性和利用共同因子 集成电路，用于控制细胞向 化学诱导剂。这个过程的关键组成部分是细胞的能力 在化学吸引剂方向的前沿产生一个伪足 细胞后部的来源和收缩。我们的目标是了解 细胞感知化学诱导剂方向的机制 并利用下游信号通路来控制这一点 细胞骨架的重组。在本应用程序中，我们重点关注角色 我们已经证明了DictyostelialPAK/Ste2O家族成员Paka的 在趋化过程中对肌球蛋白组装的调节是必不可少的，并且 RAC家族的小GTP酶。我们建议阐明以下机制： PAKA被激活以响应化学诱导剂信号并理解 调节其亚细胞定位和功能的分子相互作用 在趋化细胞的后部。此外，我们建议进行实验，以 检查rac1的激活机制，我们已经证明了这是一种 在趋化过程中控制肌动蛋白细胞骨架的关键角色。这些 研究包括研究rac1激活的动力学和调节。 和确定可能的变化，在亚细胞定位的rac1在 对化学吸引剂梯度有反应的细胞。要了解上游 Rac激活的调控，我们建议研究推测的Rac的作用 控制RAC蛋白激活的交换因子(GEF) 对各种细胞刺激的反应。利用细胞生物学和分子遗传学 方法，我们将定义RAC GEF的作用以及它们如何 是受监管的，特别关注检查其亚细胞的变化 定位和这种变化在调节定向反应中的作用。 我们建议的研究也应有助于阐明帕卡和RAC如何融入 其他信号通路对于控制细胞的功能是必不可少的 网柄苔藓细胞对化学诱导剂的定向感应和反应 渐变。了解调节PACA、RAC1和RACGEF的机制 将有助于确定控制细胞的一般机制 极化和运动应该适用于确定如何 趋化作用在广泛的细胞中受到调节。

DESCRIPTION (provided by applicant): Chemotaxis plays a central role in diverse biological processes, including metastasis of cancer cells, inflammatory responses involving movement of neutrophils and macrophage, migration of neural crest cells, embryonic morphogenesis, and aggregation in Dictyostelium. The underlying processes that control chemotaxis in eukaryotic cells are highly conserved between Dictyostelium and man and utilize common factors in integrated circuits to control directional cell movement toward a chemoattractant. The key component of this process is the ability of cells to produce a pseudopod at the leading edge in the direction of the chemoattractant source and contraction of the posterior of the cell. Our goal is to understand the mechanisms by which cells sense the direction of the chemoattractant gradient and utilize downstream signaling pathways to control this reorganization of the cytoskeleton. In this application, we focus on the role of the Dictyostelium PAK/Ste2O family member PAKa, which we have demonstrated is essential for the regulation of myosin assembly during chemotaxis, and the Rac family of small GTPases. We propose to elucidate the mechanisms by which PAKa is activated in response to chemoattractant signaling and understand the molecular interactions that regulate its subcellular localization and function in the posterior of chemotaxing cells. In addition, we propose experiments to examine the mechanism of activation of Rac1, which we have demonstrated is a key player in the control of the actin cytoskeleton during chemotaxis. These studies include investigating the kinetics and regulation of Rac1 activation and determining the possible changes in the subcellular localization of Rac1 in cells responding to a chemoattractant gradient. To understand the upstream regulation of Rac activation, we propose to examine the role of putative Rac exchange factors (GEFs) that control the activation of Rac proteins in response to various cellular stimuli. Using cell biological and molecular genetic approaches in Dictyostelium, we will define the role of Rac GEFs and how they are regulated, with a specific focus on examining changes in their subcellular localization and the role of such changes in regulating directional responses. Our proposed studies should also help elucidate how PAKa and Rac integrate into other signaling pathways that are essential for controlling the ability of Dictyostelium cells to directionally sense and respond to chemoattractant gradients. Understanding the mechanisms that regulate PAKa, Rac1, and RacGEFs in Dictyostelium will help define general mechanisms controlling cell polarization and movement that should be applicable to determining how chemotaxis is regulated in a broad range of cells.