Investigation of the VEGFR/Integrin cytoplasmic domains interaction.

描述（由申请人提供）：内皮细胞（EC）通常受肽生长因子和细胞粘附受体的信号调节。功能反应包括细胞粘附、迁移和增殖，这反过来又对血管生成过程中内皮管网络的形成等更复杂的过程至关重要。反过来，血管生成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（VEGF），启动一系列复杂的细胞内事件，诱导“内向外”信号，改变整合素的细胞外结构域的配体结合亲和力/亲和力，整合素是研究最多的一组异二聚体跨膜受体，将细胞连接到细胞外基质（ECM）。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。整合素结合触发构象变化和受体聚集，最终导致与细胞骨架相连的大细胞内蛋白复合物的产生。细胞外和细胞内区室之间的这种物理联系允许对许多细胞过程进行动态调节，包括细胞迁移、形状变化、增殖和分化。整合素aV¿3最初被确定为玻璃体连接素受体，在许多类型的血管细胞、血细胞、肿瘤和骨细胞上以可变密度表达。研究表明，VEGF/VEGF受体2 （VEGFR2）是激活内皮细胞的关键生理机制之一。VEGF刺激EC诱导aV¿3形成高亲和力状态，激活的aV¿3与VEGFR2相互作用。VEGFR2和¿3整合素之间的关系似乎是协同的，因为VEGFR2的激活诱导¿3整合素酪氨酸磷酸化，这反过来又对VEGF诱导的VEGFR2酪氨酸磷酸化至关重要。研究还表明，VEGFR2和aV¿3之间的复合物形成是血管生成调控的关键事件，但这种串扰的影响和结构要求尚未确定。在初步研究中，我们获得了一些新颖而令人兴奋的初步数据，这些数据表明VEGFR2/aV¿3细胞质尾（CT）参与了直接相互作用。两种主要EC受体之间的这种复合物的形成可能是整合素依赖功能和整体血管生成反应的主要调节机制的基础。

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.