G-PROTEIN PATHWAYS IN THE KIDNEY TRANSPLANT REJECTION

炎症机制在移植排斥反应发病机制中的作用是本项目的主要焦点。许多关键的炎症介质通过G蛋白偶联受体(GPCRs)发挥作用，G蛋白偶联受体(GPCRs)通过异源三聚体鸟嘌呤核苷酸结合蛋白(G蛋白)传递配体依赖的信号。在之前的授予期间，我们发现了两个GPCRs，血管紧张素II的AT1受体和血栓素A2的TP受体，促进同种异体免疫和移植物排斥反应。基于这些gq偶联受体的相似作用，我们假设通过不同的gpr信号来增强同种异体移植排斥反应。 与GQ蛋白、Rho GTP酶和Rho-Kinase激活有关的信号通路。此外，我们认为这些途径通过对T细胞、巨噬细胞/抗原提呈细胞和同种异体移植物本身的离散作用来影响移植物的功能。我们将使用GQ和Rho-Kinase的可诱导激活或抑制的遗传模型来验证这一假说。通过调节通过程序核心产生的移植模型中的GQ和Rho-Kinase信号，将准确地定义这些通路在排斥发病机制中的作用。我们提出的研究有以下具体目的：1.确定GQ信号促进细胞免疫反应的能力。2.研究GQ信号在器官移植排斥反应中的作用。3.定义相互作用 免疫细胞中的G蛋白和Rho-GTP酶。4.明确Rho-Kinase在排斥反应中的细胞作用机制。因为GPCRs的大家族只使用有限数量的G蛋白，我们假设增强炎症和移植物损伤的G蛋白信号通路可能是有用的治疗靶点，从而可以通过靶向单一的共同途径来阻断多个促炎配体的作用。

The contribution of inflammatory mechanisms to the pathogenesis of transplant rejection is the major focus of this program project. Many key inflammatory mediators act through G protein-coupled receptors (GPCRs) that transduce ligand-dependent signals via hetero-trimeric guanine nucleotide-binding proteins (G proteins). During the previous grant period, we showed that two GPCRs, the AT1 receptor for angiotensin II and the TP receptor for thromboxane A2, promote alloimmunity and graft rejection. Based on the similar actions of these Gq-coupled receptors, we hypothesize that allograft rejection is enhanced through distinct GPCR signaling pathways coupled to Gq proteins and to the activation of Rho GTPases and Rho-kinase. Moreover, we suggest that these pathways influence graft function through discrete actions upon the T cell, upon the macrophage/antigen-presenting cell, and upon the allograft itself. We will test this hypothesis using genetic models with inducible activation or inhibition of Gq and Rho-kinase. By modulating Gq and Rho-kinase signaling in models of transplantation generated through the program core, the contributions of these pathways to the pathogenesis of rejection will be precisely defined. Our proposed studies have the following specific aims: 1. To define the capacity of Gq signaling to promote cellular immune responses. 2. To characterize the actions of Gq signaling in organ transplant rejection. 3. To define the interactions between G proteins and Rho-GTPases in immune cells. 4. To identify the cellular mechanisms of action of Rho-kinase in rejection. Because the large family of GPCRs uses only a limited number of G proteins, we posit that G protein signaling pathways that enhance inflammation and graft injury may be useful therapeutic targets whereby the actions of multiple pro-inflammatory ligands could be blocked by targeting a single common pathway.