Investigation of the VEGFR/Integrin cytoplasmic domains interaction.

说明书(申请人提供)：血管内皮细胞(EC)通常受多肽生长因子和细胞黏附受体信号的调节。功能反应包括细胞黏附、迁移和增殖，而这些反过来又是更复杂的过程所必需的，例如在血管生成过程中内皮管网络的形成。血管生成的过程在许多疾病的发病机制中起着至关重要的作用，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，启动一系列错综复杂的细胞内事件，诱导一个由内而外的信号，改变整合素胞外结构域的配体结合亲和力/亲和力，整合素是一组连接细胞和细胞外基质(ECM)的异二聚体跨膜受体。这种生长因子介导的整合素配体结合功能的调节，通常被称为激活，在整合素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相连的大的细胞内蛋白质复合体的产生。细胞外和细胞内之间的这种物理联系允许动态调节许多细胞过程，包括细胞迁移、形状变化、增殖和分化。整合素AV？3最初被认为是玻璃体连接素受体，在许多类型的血管细胞、血细胞、肿瘤和骨细胞上以不同的密度表达。已有研究表明，血管内皮细胞激活血管内皮细胞的重要生理机制之一是通过血管内皮生长因子/血管内皮生长因子受体2(VEGFR2)。血管内皮生长因子刺激内皮细胞形成高亲和力的血管内皮生长因子3，并且激活的血管内皮生长因子3与血管内皮生长因子2相互作用。VEGFR2和3整合素之间的关系似乎是协同的，因为VEGFR2激活诱导3整合素酪氨酸磷酸化，而3整合素酪氨酸磷酸化是血管内皮生长因子诱导的VEGFR2酪氨酸磷酸化的关键。研究还表明，VEGFR2和AV3之间的复合体的形成是调节血管生成的关键事件，但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，这些数据表明VEGFR2/AV？3细胞质尾巴(CT)参与了直接相互作用。两个主要的EC受体之间的这种复杂的形成可能是调节整合素依赖的功能和整个血管生成反应的主要调控机制。 公共卫生相关性：这项提案提出了在VEGFR2和整合素胞浆尾巴之间存在复合体的证据。我们将研究这种相互作用的确切机制和作用：血管内皮生长因子-整合素伙伴关系可能成为生长因子和细胞黏附系统之间信息交流的重要基础研究模型。我们的数据可能最终导致一个新的范式来理解血管内皮生长因子和整合素是如何相互作用并调节复杂的细胞黏附事件和血管生成反应的。此外，我们的结构方法应该有助于开发新的治疗药物，旨在抑制整合素(和其他受体)胞浆区域蛋白质与蛋白质的相互作用。

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.