G-PROTEIN PATHWAYS IN THE KIDNEY TRANSPLANT REJECTION

炎症机制对移植排斥发病机制的贡献是该项目的主要焦点。许多关键的炎症介质通过G蛋白偶联受体（GPCR）起作用，GPCR通过异源三聚体鸟嘌呤核苷酸结合蛋白（G蛋白）抑制配体依赖性信号。在上一个资助期间，我们发现两个GPCR，血管紧张素II的AT 1受体和血栓素A2的TP受体，促进同种异体免疫和移植排斥反应。基于这些Gq偶联受体的相似作用，我们假设同种异体移植排斥反应通过不同的GPCR信号传导而增强 与Gq蛋白和Rho GTP酶和Rho激酶的活化偶联的途径。此外，我们认为，这些途径通过对T细胞、巨噬细胞/抗原呈递细胞和同种异体移植物本身的离散作用来影响移植物功能。我们将使用具有Gq和Rho激酶的诱导性激活或抑制的遗传模型来检验这一假设。通过调节Gq和Rho激酶信号传导在移植模型中产生通过程序的核心，这些途径的排斥反应的发病机制的贡献将被精确定义。我们的研究有以下具体目标：1。确定Gq信号转导促进细胞免疫应答的能力。2.探讨Gq信号在器官移植排斥反应中的作用。3.来定义 免疫细胞中的G蛋白和Rho-GTP酶。4.明确Rho激酶在排斥反应中的细胞作用机制。由于GPCR的大家族仅使用有限数量的G蛋白，因此我们认为增强炎症和移植物损伤的G蛋白信号传导途径可能是有用的治疗靶点，从而可以通过靶向单个共同途径来阻断多种促炎配体的作用。

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.