Regulation of Actin Dynamics During T Cell Activation

描述（由申请人提供）：实验和临床研究强调了T细胞在增强抗肿瘤反应及其在炎症中的病理作用方面的潜力。因此，了解T细胞激活过程中使用的信号转导机制的努力为开发在需要时从药理学或遗传学角度增强或抑制T细胞功能的策略提供了基础。肌动蛋白细胞骨架及其调节因子在t细胞受体（TCR）、共刺激和整合素介导的信号传导中发挥关键作用。我们的初步数据表明，三种肌动蛋白调节蛋白Dynamin 2、Vav1和WAVE2的动态相互作用影响TCR参与后细胞骨架的变化和激酶级联的激活。本提案中概述的机制实验将通过验证以下中心假设，从功能上表征Dyn2及其效应分子在TCR交联后肌动蛋白介导的过程中的作用：Dyn2通过在T细胞- ARC接触部位作为肌动蛋白调节蛋白组装的分子支架，有助于T细胞活化。此外，我们提出新的Dyn2-Vav1相互作用是Vav1定位到免疫突触的必要条件，在免疫突触上它将激活其靶分子Rac1。此外，我们提供的证据表明，rac1调控的WAVE2复合物作为Dyn2的靶标，在T细胞活化中起着关键作用。为了验证我们的中心假设，我们将(1)确定Dynamin 2在T细胞活化中的作用；(2)确定Vav1调控Dynamin 2介导的调控事件的机制；(3)确定Abi-WAVE2复合物在T细胞中的作用。总之，这些研究将为理解参与T细胞活化调节的分子事件提供实验基础，并将在更广泛的背景下，推进我们对淋巴细胞活化过程中肌动蛋白细胞骨架动力学的基本过程的理解。

DESCRIPTION (provided by applicant): Experimental and clinical studies highlight the potential for T cells in enhancing anti-tumor response and their pathological role in inflammation. Thus, efforts aimed at understanding the signal transduction mechanisms utilized during T cell activation provide a foundation for developing strategies to pharmacologically or genetically enhance or suppress T cell functions when needed. The actin cytoskeleton and its regulators play a key role in T-cell receptor (TCR)-, costimulatory-, and integrin-mediated signaling. Our preliminary data suggest that the dynamic interaction of three actin-regulatory proteins, Dynamin 2, Vav1 and WAVE2 influence cytoskeletal changes and the activation of kinase cascades following TCR engagement. The mechanistic experiments outlined in this proposal will functionally characterize the role of Dyn2 and its effector molecules in actin-mediated processes following TCR crosslinking by testing the central hypothesis that: Dyn2 contributes to T cell activation by functioning as a molecular scaffold for the assembly of actin regulatory proteins at the T cell - ARC contact site. In addition, we propose that the novel Dyn2-Vav1 interaction is required for the localization of Vav1 to the immunological synapse where it will activate its target molecule Rac1. Moreover, we provide evidence that identifies a role for the Rac1-regulated WAVE2 complex as a target of Dyn2 that plays a key role in T cell activation. In order to test our central hypothesis, we will (1) Determine the role of Dynamin 2 in T cell activation; (2) Determine the mechanism by which Vav1 regulates Dynamin 2-mediated regulatory events; and (3) Determine the role of the Abi-WAVE2 complex in T cells. Together, these studies will provide an experimental basis for understanding the molecular events that are involved in the regulation of T cell activation, and will in a broader context, advance our understanding of fundamental processes involved in actin cytoskeletal dynamics during lymphocyte activation.