Investigation of the VEGFR/Integrin cytoplasmic domains interaction.

描述（由申请人提供）：内皮细胞（EC）通常由肽生长因子和细胞粘附受体的信号传导调节。功能性反应包括细胞粘附、迁移和增殖，而这又是更复杂的过程所必需的，例如血管生成期间内皮管网络的形成。血管生成过程反过来在许多疾病的发病机制中起关键作用，包括但不限于肿瘤生长/转移、糖尿病视网膜病变和损伤后的组织重塑。在血管生成过程中，新产生的生长因子，包括血管内皮生长因子（VEGF），引发一系列复杂的细胞内事件，其诱导改变整联蛋白胞外结构域的配体结合亲和力/亲合力的“由内而外”信号，整联蛋白是将细胞连接至胞外基质（ECM）的异二聚体跨膜受体的研究最多的组。这种生长因子介导的整联蛋白配体结合功能的调节，通常称为激活，在整联蛋白家族对血液和血管细胞反应的调节中最为明显。整合素结合触发受体的构象变化和聚集，最终导致与细胞骨架连接的大的细胞内蛋白质复合物的产生。细胞外和细胞内区室之间的这种物理连接允许动态调节许多细胞过程，包括细胞迁移、形状改变、增殖和分化。整合素α V 3，最初被鉴定为玻连蛋白受体，在许多类型的血管细胞、血细胞、肿瘤和骨细胞上以可变密度表达。已经证明，内皮上aV 3活化的关键生理机制之一是通过VEGF/VEGF受体2（VEGFR 2）。VEGF刺激EC诱导形成高亲和力状态的aV 3，此外，活化的aV 3与VEGFR 2相互作用。VEGFR 2和<$3整联蛋白之间的关系似乎是协同的，因为VEGFR 2活化诱导<$3整联蛋白酪氨酸磷酸化，这反过来对VEGF诱导的VEGFR 2酪氨酸磷酸化至关重要。还已经表明，VEGFR 2和aV 3之间的复合物形成是调节血管生成的关键事件，但是这种串扰的影响和结构要求尚未确定。在初步研究中，我们获得了一些新的和令人兴奋的初步数据，这表明VEGFR 2/aV 3胞质尾（CT）参与直接相互作用。两个主要EC受体之间的这种复合物形成可能是调节整合素依赖性功能和整体血管生成反应的主要调节机制的基础。 公共卫生相关性：该提案提供了证据，证明VEGFR 2和整合素胞质尾之间存在复合物。我们将研究这种相互作用的确切机制和作用：VEGF整合素的伙伴关系可能作为一个重要的模型，为基础研究的生长因子和细胞粘附系统之间的通信。我们的数据可能最终导致一个新的范式，了解如何VEGF和整合素的串扰和调节复杂的细胞粘附事件和血管生成反应。此外，我们的结构方法应有助于开发新的治疗药物，旨在抑制整合素（和其他受体）胞质结构域蛋白质-蛋白质相互作用。

DESCRIPTION (provided by applicant): The endothelial cells (EC) are often regulated by the signaling from the peptide growth factors and the cellular adhesion receptors. The functional responses include cell adhesion, migration and proliferation, which, in turn, are essential for more complex processes such as formation of the endothelial tube network during angiogenesis. The process of angiogenesis, in turn, plays a crucial role in the pathogenesis of numerous diseases, including but not limited to tumor growth/metastasis, diabetic retinopathy, and tissue remodeling upon injury. During angiogenesis newly produced growth factors, including Vascular Endothelial Growth Factor (VEGF), initiate a series of intricate intracellular events which induce an "inside-out" signal that alters the ligand binding affinity/avidity of the extracellular domains of integrins, the most studied group of heterodimeric transmembrane receptors that connect cells to the extracellular matrix (ECM). Such growth-factor-mediated modulation of integrin ligand binding function, commonly referred to as activation, is most clearly evident in the regulation of blood and vascular cell responses by the ¿ integrin family. Integrin binding triggers conformational changes and clustering of receptors, ultimately leading to the generation of large intracellular protein complexes linked to the cytoskeleton. This physical linkage between extracellular and intracellular compartments allows dynamic regulation of many cellular processes including cell migration, shape change, proliferation and differentiation. Integrin aV¿3, originally identified as the vitronectin receptor, is expressed at variable density on many types of vascular cells, blood cell, tumors and osteocells. It has been demonstrated that one of the key physiological mechanisms of aV¿3 activation on endothelium is via VEGF/VEGF receptor 2 (VEGFR2). EC stimulation by VEGF induces formation of the high affinity state of aV¿3 and, moreover, activated aV¿3 interacts with VEGFR2. A relationship between VEGFR2 and ¿3 integrin appears to be synergistic, since VEGFR2 activation induces ¿3 integrin tyrosine phosphorylation, which, in turn, is crucial for VEGF induced tyrosine phosphorylation of VEGFR2. It has been also shown that the complex formation between VEGFR2 and aV¿3 is crucial event in regulation of angiogenesis, but the impact and structural requirements for this crosstalk have yet to be determined. In preliminary studies, we have obtained some novel and exciting preliminary data, which suggest that VEGFR2/aV¿3 cytoplasmic tails (CT) are involved in direct interaction. This complex formation between two major EC receptors may underlie a major regulatory mechanism for the regulation of the integrin-dependent functions and for the overall angiogenic response. PUBLIC HEALTH RELEVANCE: This proposal presents the evidence that there is a complex between VEGFR2 and integrin ¿ cytoplasmic tails. We will investigate the exact mechanisms and the role of this interaction: the VEGF-integrin partnership may serve as an important model for fundamental studies of the communication between growth factors and cell adhesion systems. Our data may ultimately lead to a new paradigm for understanding how VEGF and integrin cross talk and regulate the complex cell adhesion events and angiogenic response. Moreover, our structural approach should contribute to the development of new therapeutic agents designed to inhibit integrin (and other receptors) cytoplasmic domain protein-protein interactions.