The role of the cAMP responsive protein AKAP9 in integrin mediated T cell recruitment to the kidney in acute kidney injury

急性肾损伤（AKI）的特征是肾脏功能的突然丧失。尽管技术进步，AKI的死亡率几十年来一直高达60%。t细胞，特别是自然杀伤t细胞，被证明在肾损伤的病理生理中发挥关键作用，因为缺乏t细胞的小鼠可以免受AKI的侵害。白细胞招募依赖于ý2-integrins的激活，ý2-integrins与它们的对抗受体相互作用，介导细胞阻滞和炎症组织的连续浸润。通过g蛋白偶联受体（GPCR）激活整合素受cAMP调控，cAMP是一种普遍存在的细胞第二信使，参与多种信号通路。尽管发现cAMP在趋化因子的作用下抑制白细胞整合素的激活，但这种现象的分子机制仍然难以捉摸。一个新兴的概念是，a激酶锚定蛋白（AKAPs）通过靶向亚细胞结构的效应蛋白亚群来区分cAMP反应。在白细胞中，AKAP9与ý2-integrin白细胞功能抗原1 （LFA-1）相关，cAMP效应蛋白激酶A的抑制导致LFA-1活化增加。通过条件敲除CD4+和CD8+ t细胞中缺乏AKAP9的小鼠，本项目旨在研究AKAP9在cAMP依赖性LFA-1调控中的重要性。我们采用了一种综合的方法，结合了导致整合素激活和关键分子时空分布的信号通路的体外分析，以及使用活体显微镜评估t细胞向炎症血管壁募集的体内研究，并在急性肾衰竭小鼠模型中验证了我们假设的临床重要性。

Acute kidney injury (AKI) is characterized by an abrupt loss of kidney function. Despite technological advances, mortality rate of AKI has remained as high as 60% for decades. T-cells, specifically natural killer T-cells, were demonstrated to play critical roles in the pathophysiology of kidney injury as mice deficient in T-cells are protected from AKI. Leukocyte recruitment relies on the activation of ý2-integrins which interact with their counter-receptors to mediate cell arrest and consecutive infiltration of inflamed tissues.Integrin activation via G-protein coupled receptors (GPCR) is regulated by cAMP, an ubiquitous cellular second messenger that is involved in multiple signaling pathways. Even though cAMP was found to inhibit leukocyte integrin activation in response to chemokines, the molecular mechanism for this phenomenon remains elusive. An emerging concept is that A-kinase anchor proteins (AKAPs) serve to compartmentalize cAMP responses by targeting a subset of effector proteins to subcellular structures. In leukocytes, AKAP9 associates with the ý2-integrin leukocyte functioning antigen 1 (LFA-1) and inhibition of the cAMP effector protein kinase A results in increased LFA-1 activation.By using conditional knock-out mice deficient for AKAP9 in CD4+ and CD8+ T-cells this project aims to examine the importance of AKAP9 for cAMP dependent regulation of LFA-1. A comprehensive approach incorporating in vitro analysis of the signaling pathways leading to integrin activation and spatiotemporal distribution of key molecules as well as in vivo studies assessing the recruitment of T-cells to the inflamed vessel wall using intravital microscopy is deployed and the clinical importance of our hypothesis is tested in a murine model of acute kidney failure.