The role of endothelial cortactin in vascular permeability and leukocyte extravasation

白细胞外渗是炎症反应的核心组成部分，发生在一系列分子事件中，包括粘附、信号传导和细胞骨架重塑。如果控制不当，过量的外渗可导致慢性炎症性疾病。我们已经证明，内皮层调节血管通透性和中性粒细胞外渗在体内的炎症部位。在功能研究中，我们证明了接触素控制小gtpase的活性：Rap1在接触素缺乏的细胞中活性较低，而RhoG在白细胞与内皮细胞结合时不能被激活。我的初步数据表明，血管活性肽肾上腺髓素（ADM）和Rap1激活剂PDZ-GEF2支持接触素介导的内皮功能调节。此外，我们发现白细胞的主要内皮受体ICAM-1在没有接触的情况下不能聚集在白细胞周围。在这个项目中，我想要揭示接触蛋白调节白细胞外渗和血管通透性的分子机制。我将分析接触是否作为支架来协调控制GTPase激活所需的分子机制。此外，我将研究接触如何调节ICAM-1聚集来控制白细胞外渗。这可以通过将ICAM-1连接到肌动蛋白细胞骨架和/或通过白细胞捕获下游的干扰信号转导发生。我还将在炎症条件下寻找新的接触的结合伙伴，以及在没有接触的情况下差异调节的蛋白质。这些研究结果将阐明免疫应答中接触蛋白介导的信号传导机制，并可能确定接触蛋白作为慢性炎症疾病新治疗策略的靶点。

Leukocyte extravasation is a central component of the inflammatory response and occurs in a series of molecular events including adhesion, signaling and cytoskeletal remodeling. If not controlled properly, excessive extravasation can lead to chronic inflammatory diseases. We have shown that endothelial cortactin regulates vascular permeability and neutrophil extravasation at sites of inflammation in vivo. In functional studies, we demonstrated that cortactin controls the activity of small GTPases: Rap1 is less active in cortactin-deficient cells, whereas RhoG cannot be activated upon leukocyte binding to endothelial cells. My preliminary data suggest that the vasoactive peptide adrenomedullin (ADM) and the Rap1 activator PDZ-GEF2 support cortactin-mediated regulation of endothelial functionality. Moreover, we found that the major endothelial receptor for leukocytes, ICAM-1, cannot cluster around leukocytes without cortactin. In this project, I want to unravel the molecular mechanisms by which cortactin regulates leukocyte extravasation and vascular permeability. I will analyze if cortactin acts as scaffold to coordinate the molecular machinery required for controlled GTPase activation. Additionally, I will examine how cortactin regulates ICAM-1 clustering to control leukocyte extravasation. This can occur through connecting ICAM-1 to the actin cytoskeleton and/or via disturbed signal transduction downstream of leukocyte capture. I will also search for new binding partners of cortactin under inflammatory conditions and for proteins that are differentially regulated in the absence of cortactin. The results of these studies will clarify the mechanisms of cortactin-mediated signaling during the immune response and may identify cortactin as target in novel treatment strategies for chronic inflammatory disorders.