Analyzing the role of the Ras effector TJ1 in controlling chemotaxis in Dictyostelium discoideum

趋化作用在细胞形态发生、先天免疫、炎症和癌细胞转移等多种生物学过程中发挥着重要作用。细胞对较浅的细胞外梯度做出反应，这些梯度通过RAS、RAP1和PI3K的局部激活而在细胞内高度放大，导致F-肌动蛋白在前沿聚合。RAS是趋化因子介导的PI3K活性的重要上游激活剂；然而，遗传数据表明，肯定还有其他RAS效应分子调节趋化作用。Firtel实验室最近发现了一种新的RAS效应器TJ1，它是MRL(Mig10/riam/LPD)接头蛋白家族的成员，他们已经证明，这是正确的趋化所必需的。通过使用细胞生物学和分子遗传学的方法，我建议剖析TJ1的功能和调控，以更深入地了解RAS信号如何控制趋化作用。我将使用生化方法来鉴定TJ1的结合伙伴，并利用突变研究来剖析TJ1是如何调控和发挥作用的。此外，我还将研究TJ1和RAS信号在控制控制细胞运动的力的载体中的作用。

Chemotaxis plays a central role in various biological processes such as cellular morphogenesis, innate immunity, inflammation, and metastasis of cancer cells. Cells respond to shallow extracellular gradients which become highly amplified intracellularly via the localized activation of Ras, Rap1, and PI3K resulting in F-actin polymerization at the leading edge. Ras is an important upstream activator of chemoattractant-mediated PI3K activity; however, genetic data indicate that there must be other Ras effectors regulating chemotaxis. The Firtel lab recently identified a new Ras effector TJ1, a member of the MRL (Mig10/RIAM/Lpd) family of adaptor proteins, which they have shown is required for proper chemotaxis. Through the use of cell biological and molecular genetic approaches, I propose to dissect the function and regulation of TJ1, to obtain greater insight into how Ras signalling controls chemotaxis. I will use biochemical approaches to identify the binding partners of TJ1 and employ mutational studies to dissect how TJ1 is regulated and functions. In addition, I will examine the role of TJ1 and Ras signalling in controlling the vectors of the forces that control cell movement.