Regulation of Integrin Signaling by Adapter Proteins

整合素是在细胞粘附和迁移中起关键作用的二聚体细胞表面受体。 对整联蛋白功能至关重要的信号传导事件包括由其他细胞表面受体引发的第二信使级联，其调节整联蛋白对其配体的亲合力，以及由整联蛋白本身的接合引发的信号传导途径。我们和其他人已经发现，由衔接蛋白成核的多分子复合物的形成对于向整合素的信号传导（由内向外信号传导）和通过整合素的信号传导（由外向内信号传导）都是必不可少的。本实验室长期以来一直对含有76 kDa白细胞磷蛋白（SLP-76）的SH 2结构域感兴趣，SLP-76是一种造血限制性衔接蛋白，对免疫受体和整合素的功能至关重要。本提案中描述的实验将利用生物化学、成像、分子和遗传方法来研究SLP-76及其相关分子在先天性和适应性免疫系统细胞中的整合素应答中的作用。 这项工作将分为三个具体目标。第一个将探索SLP-76和其他蛋白质之间的诱导性相互作用后，整合素的参与和SLP-76的亚细胞定位过程中， 整合素在T细胞中的功能。一个将被测试的中心假设是，在细胞中存在两个SLP-76池，一个调节免疫受体信号传导，第二个调节整联蛋白反应。 我们将进一步测试整合素途径需要SLP-76与三种衔接蛋白ADAP（粘附和脱颗粒促进衔接蛋白）、SKAP 55（55 kDa Src激酶相关磷蛋白）和RIAM（Rap 1-GTP相互作用衔接分子）之间的相互作用，以及这些衔接子共同使复合物成核，将活化的Rap-1带到细胞表面的概念。第二个目的 该提案的第一部分将通过产生遗传上独特的鼠系来进行Aim 1的体内生物化学和成像研究，在所述鼠系中表达SLP-76或其相关分子的突变，所述突变被预测为选择性地影响T细胞免疫受体或整联蛋白功能。第三个目标将我们的工作扩展到先天性免疫系统，通过研究这些适配器分子在中性粒细胞中协调的生物化学和分子事件，包括离体和体内。本项目中描述的实验将广泛使用这两个科学核心，并将广泛依赖于与项目负责人的互动。 这个项目的其他项目。我们希望这些研究将为多分子复合物如何整合导致适当免疫细胞反应的信号通路提供新的见解。

Integrins are dimeric cell surface receptors that play critical roles in cellular adhesion and migration. Signaling events critical for integrin function include second messenger cascades initiated by other cell surface receptors which modulate integrin avidity for their ligands in addition to signaling pathways initiated by engagement of integrins themselves. We and others have found that the formation of multimolecular complexes nucleated by adapater proteins is essential for both signaling to integrins (inside-out signaling) and signaling by integrins (outside-in signaling). Our laboratory has a long standing interest in the SH2 domain containing leukocyte phosphoprotein of 76kDa (SLP-76), a hematopoietic restricted adapater protein that is critical for function of both immunoreceptors and integrins. The experiments described in this proposal will make use of biochemical, imaging, molecular and genetic approaches to investigate the role of SLP-76 and its associated molecules in integrin responses in cells of both the innate and adaptive immune systems. The work will be divided into three specific aims. The first will explore the inducible interactions between SLP-76 and other proteins upon integrin engagement and the subcellular localization of SLP-76 during integrin function in T cells. One central hypothesis that will be tested is that there are two pools of SLP-76 in the cell, one which regulates immunoreceptor signaling and the second which regulates integrin responses. We will further test the notion that integrin pathway requires an interaction between SLP-76 and three adapter proteins, ADAP (Adhesion and Degranulation-promoting Adapter Protein), SKAP55 (SrcKinase-associated phosphoprotein of 55kDa), and RIAM (Rap1-GTP interacting adapter molecule), and that these adapters collectively nucleate a complex which brings activated Rap-1 to the cell surface. The second aim of this proposal will take the biochemical and imaging studies of Aim 1 in vivo by generating genetically unique murine lines in which mutations of SLP-76 or its associated molecules are expressed that are predicted to selectively impact T cell immunoreceptor or integrin function. The third aim will extend our work to the innate immune system by studying the biochemistry and molecular events coordinated by these adapter molecules in neutrophils, both ex vivo and in vivo. Experiments described in this project will make extensive use of both scientific cores and will rely extensively on interactions with the Project Leaders of the other projects of this program. We hope that these studies will provide new insights into how multimolecular complexes integrate signaling pathways leading to appropriate immune cell responses.