Integrin activation during neutrophil adhesion and vascular inflammation

中性粒细胞是宿主防御细菌和真菌感染所必需的， 组织坏死或缺血性损伤后的炎症。如果没有适当解决， 炎症是多种人类炎性疾病背后的驱动力。中性粒细胞到达 从血流中清除受伤部位，先滚动，然后停止。趋化因子触发了细胞停滞 诱导高亲和性构象2整合素。两种FERM结构域蛋白，kindlin-3和 talin-1是嗜中性粒细胞抑制所必需的。众所周知，talin-1是一种与细胞膜结合的衔接蛋白， 肌动蛋白细胞骨架通过结合和改变细胞骨架的拓扑结构来激活整合素。跨膜 域我们最近报道Kindlin-3通过其pleckstrin被募集到质膜上 在嗜中性粒细胞停滞之前同源域。然而，中性粒细胞扩散和 Kindlin-3在这一过程中的作用知之甚少。此外，kindlin-3如何与talin-1合作 激活整联蛋白，以及Kindlin-3是否也通过直接结合肌动蛋白而作为接头蛋白发挥作用 是完全未知的。我们的总体假设是，在中性粒细胞扩散过程中， 和talin-1同时被募集到质膜，在那里kindlin-3组织高亲和力的 整合素活化。为了验证这一假设，我们产生了用于同时检测的报告小鼠系 关于.. 2小鼠中性粒细胞中kindlin-3和talin-1的整合素活化和成像。在目标1中，我们将测试 假设Kindlin-3组织成簇的高亲和力的环。中性粒细胞铺展过程中的2种整合素 在目的2中，我们将检验kindlin-3通过以下方式调节整联蛋白活化的假设： 直接与肌动蛋白细胞骨架结合;在目标3中，我们将确定.. 2整合素活化 缺血再灌注损伤（IRI）。该研究具有创新性， 因为它将解决Kindlin-3如何组织高亲和力整合素激活的谜团 并确定它在虹膜炎性反应中的作用。成功完成此提案将 建立整联蛋白激活分子机制，并提供中性粒细胞的机制见解 扩散和血管炎症。

Neutrophils, which are essential for host defense against bacterial and fungal infections, induce inflammation following tissue necrosis or ischemic injury. If not properly resolved, neutrophilic inflammation is the driving force behind a plethora of human inflammatory diseases. Neutrophils arrive at the site of injury from the bloodstream by first rolling and then arresting. Arrest is triggered by chemokines that induce the high-affinity conformation of ..2 integrins. Two FERM domain proteins, kindlin-3 and talin-1, are required for neutrophil arrest. It is well known that talin-1, an adaptor protein that binds the actin cytoskeleton, activates integrins by binding and altering the topology of the .. transmembrane domain. We recently reported that kindlin-3 is recruited to the plasma membrane through its pleckstrin homology domain prior to neutrophil arrest. However, the mechanism underlying neutrophil spreading and the role of kindlin-3 in this process are poorly understood. Moreover, how kindlin-3 cooperates with talin-1 to activate integrins and whether kindlin-3 also functions as an adaptor protein by directly binding to actin are completely unknown. Our overarching hypothesis is that, during neutrophil spreading, both kindlin-3 and talin-1 are simultaneously recruited to the plasma membrane, where kindlin-3 organizes high-affinity integrin activation. To test this hypothesis, we generated reporter mouse lines for simultaneous detection of ..2 integrin activation and imaging of kindlin-3 and talin-1 in mouse neutrophils. In Aim 1, we will test the hypothesis that kindlin-3 organizes a ring of clustered high-affinity ..2 integrins during neutrophil spreading under flow conditions; in Aim 2, we will test the hypothesis that kindlin-3 regulates integrin activation by directly binding to the actin cytoskeleton; and in Aim 3, we will determine the role of ..2 integrin activation in ischemia-reperfusion injury (IRI). The proposed research is conceptually innovative and highly significant because it will resolve the enigma of how kindlin-3 organizes high-affinity integrin activation and define the role it plays in IRI-induced inflammation. Successful completion of this proposal will establish molecular mechanisms of integrin activation and provide mechanistic insight into neutrophil spreading and vascular inflammation.