AlphaVbetaIII Activation in Blood and Endothelial Cells in Angiogenesis

整合素B3亚家族是在细胞生物学中发挥重要作用的双向信号传导受体。它们对血小板功能和血管生物学的影响尤为突出。aVB 3受体作为血管生成的重要调节剂，血管生成是成年生物体中血管生长的过程，其是许多病理学的基础，包括缺血性损伤、癌症和组织修复。最近的研究表明，血管生成是一个系统性过程，其中血管细胞与血液和组织来源的免疫细胞以及循环血液成分协调作用。使用多种体内模型，我们已经表明aVB 3的激活发生在活跃血管生成位点的内皮上，并且似乎控制几种血管生成依赖性反应，包括缺血后的恢复、肿瘤生长和伤口愈合。使用敲入小鼠模型 表达不能进行磷酸化的B3的突变形式，我们证明B3磷酸化是体内新血管形成所必需的。然而，B3基因敲入小鼠中的异常血管生成被骨髓移植完全逆转，并且似乎主要由骨髓衍生（BMDC）细胞上的B3整合素决定。许多这些募集的细胞表达CXCR 4，一种SDF-1的受体。此外，SDF-1处理BMDC似乎通过β 3整合素调节细胞粘附。这些研究确定了B3整合素在血管生成中的一种新的和非常规的功能，并强调血管生成的过程涉及许多细胞类型和组织的合作。待检验的总体假设是aVB 3激活和 磷酸化对于血液、骨髓来源的细胞和内皮细胞之间的体内协作是必需的。 提出以下具体目标来检验我们的假设：目标I。目的探讨整合素β 3的活化和磷酸化在血管生成过程中对内皮细胞、骨髓源性细胞和血小板相互作用的影响。双转基因系DiYF-GFP和p3-/- GFP小鼠将用于骨髓嵌合体中BMDC的可视化。我们还将确定血小板B3对血管生成和BMDC募集的作用。Aim II.评估控制循环血细胞和内皮细胞之间相互作用的分子和细胞机制，并确定p3整合素在此过程中的作用。将使用来自WT、B3-/-和B3敲入小鼠的内皮细胞和BMDC细胞以及以整合素活化受损为特征的细胞（来自项目1和2）。Aim III.评估整合素活化在p3整合非依赖性细胞凋亡过程中的作用。 BMDC与内皮细胞的粘附。我们将确定SDF-1/CXCR 4轴在整合素介导的反应中的作用。这些研究将描绘血管生成的细胞和分子机制，并导致识别新的治疗策略，以治疗缺血，创伤和其他病理。

The B3 subfamily of integrins are two-way signaling receptors that play essential roles in cell biology. Their influences on platelet function and vascular biology are particularly prominent. aVB3 receptor serves as a crucial regulation of angiogenesis, the process of blood vessel growth in adult organism which underlies a number of pathologies, including ischemic injury, cancer and tissue repair. Recent studies demonstrated that angiogenesis is a systemic process where vascular cells coordinate actions with immune cells of blood and tissue origin, and circulating blood components. Using a variety of in vivo models we have shown that activation of aVB3 occurs on endothelium at the sites of active angiogenesis and appears to control several angiogenesis-dependent responses including recovery after ischemia, tumor growth and wound healing. Using a knockin mouse model expressing mutant form of B3 unable to undergo phosphorylation, we demonstrated that B3 phosphorylation is essential for neovascularization in vivo. However, abnormal angiogenesis in B3 knockin mice was completely reversed by bone marrow transplantation was and appear to be dictated primarily by B3 integrin on bone marrow derived (BMDC) cells. Many of these recruited cells express CXCR4, a receptor for SDF-1. Moreover, SDF-1 treatment of BMDC seems to modulate cell adhesion via (33 integrin. These studies identified a novel and unconventional function of B3 integrin in angiogenesis and emphasizes that the process of angiogenesis involve co-operation of numerous cell types and tissues. The overall hypothesis to be tested is that aVB3 activation and phosphorylation are essential for in vivo cooperation between blood, bone marrow-derived and endothelial cells. The following Specific Aims are proposed to test our hypothesis: Aim I. To assess the role of p3 integrin activation and phosphorylation on the interactions between endothelial, bone marrow derived cells and platelets during angiogenesis in vivo. Double transgenic lines, DiYF-GFP and p3-/- GFP mice will be utilized for visualization of BMDC in bone marrow chimeras. We will also determine the role of platelet B3 on angiogenesis and recruitment of BMDC. Aim II. To assess the molecular and cellular mechanisms controlling interaction between circulating blood cells and endothelium and determine the role of p3 integrin in this process. Endothelial and BMDC cells from WT, B3-/- and B3 knockin mice as well as cells characterized by impaired integrin activation (from Project 1 and 2) will be used. Aim III. To assess the role of integrin activation in the process of p3 integrindependent adhesion of BMDC to endothelium. We will determine the role of SDF-1/CXCR4 axis in integrinmediated responses. These studies will delineate the cellular and molecular mechanisms of angiogenesis and result in identification of novel therapeutic strategies to treat ischemia, wound and other pathologies.