Regulation of Integrins in Neovasculature Development

描述(申请人提供)：血管生成过程在许多疾病的发病机制中起着关键作用，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。血管生成是由血管内皮生长因子(VEGF)和细胞黏附受体、内皮细胞和血细胞上的整合素驱动的。我们已经证明，血管生成中的关键调控事件之一是血管内皮生长因子受体2和血管内皮生长因子3整合素之间的相互作用。然而，这种串扰的病理后果和结构要求尚未确定。我们已经证明，许多整合素依赖的功能是由Akt途径控制的。然而，由于下游靶点的复杂性，Akt亚型在调节不同的血管生成细胞事件中的确切作用仍然知之甚少。作为我们的具体假设，我们认为VEGFR2/AV？3复合体对整合素依赖的功能和整个血管生成反应的调节至关重要；Akt激酶通路在病理性血管生成过程中对整合素活性和细胞外基质组成的调节起着核心作用。为了检验这些假说，我们提出了以下具体目标。目的1：确定3整合素与血管内皮生长因子2形成的复合体在体内外的结构要求和生物学作用。为了证明该复合体的关键调控作用，我们将使用最近产生的和表征的化合物来破坏它。？3/VEGFR2复合体的作用将在体外血管生成相关检测中进行评估。该复合体在体内移植的肿瘤、伤口和缺血组织中的作用将被阐明。将特别考虑整合素和3/VEGFR2复合体在调节骨髓来源细胞向新生血管募集中的作用。这些研究不仅将确定血管生成的基本机制，还将导致新的抗血管生成策略的产生。目的：进一步阐明Akt通路对整合素和细胞外基质的调控机制。A)利用我们实验室最近鉴定的Akt-1和Akt-2缺失小鼠，我们将进一步阐明Akt信号在整合素活性调节中的作用。Akt1/2信号在调节整合素依赖的细胞外基质表达和组装中的作用将被确定。由于Akt1影响了许多参与血管生成的细胞类型的功能，我们将定义内皮Akt1在血管生成中的作用。对血管生成的发起者血管内皮生长因子、效应系统和整合素之间如何成功合作的详细了解，将为在心脏病学、血管医学和癌症治疗中开发新的治疗策略奠定基础。与公共卫生相关：适应心肌梗死或外周血管疾病引起的区域性缺血的主要机制是发展新的血管，这一过程被称为“血管生成”。在癌症中，血管生成的抑制会抑制肿瘤的生长。血管生成是由血管内皮生长因子启动的，依赖于整合素受体的功能。为了能够“建造”有功能的血管或抑制其形成，需要对血管生成的机制有详细的了解。这项建议的目的是评估血管生成的分子和细胞机制，重点是病理生理学相关的模型。

DESCRIPTION (provided by applicant): The process of angiogenesis plays a crucial role in the pathogenesis of numerous diseases, including but not limited to tumor growth/metastasis, diabetic retinopathy, and in tissue remodeling upon injury. Angiogenesis is driven by Vascular Endothelial Growth Factor (VEGF) and cell adhesion receptors, integrins on endothelial and blood cells. We have shown that one of the crucial regulatory events in angiogenesis is the cross-talk between VEGF receptor 2 and aV¿3 integrin. However, the pathological consequences and structural requirements for this crosstalk have yet to be determined. We have shown that a number of integrin-dependent functions are controlled by Akt pathway. However, due to the complexity of downstream targets, the exact role of Akt isoforms in the regulation of distinct cellular events of angiogenesis remains poorly understood. As our specific hypotheses, we propose that VEGFR2/ aV¿3 complex is crucial for the regulation of integrin-dependent functions and for the overall angiogenic response; and that Akt kinase pathway plays a central role in regulation of integrin activity and extracellular matrix composition during pathological angiogenesis. The following Specific Aims are proposed to test these hypotheses. Aim 1: To determine the structural requirements and the biological role of the complex between ¿3 integrin and VEGFR2 in vitro and in vivo. In order to demonstrate the key regulatory role of the complex, we will disrupt it using recently generated and characterized compounds. The role of the ¿3/VEGFR2 complex will be assessed in angiogenesis-related assays in vitro. The role of the complex will be elucidated in vivo in implanted tumors, wounds and ischemic tissues. Special consideration will be given to the role of ¿3 integrin and ¿3/VEGFR2 complex in the regulation of bone marrow-derived cell recruitment to neovasculature. These studies will not only determine the basic mechanisms of angiogenesis, they will lead to the generation of a new anti-angiogenic strategy. Aim 2: To further elucidate the mechanisms of integrin and extracellular matrix regulation by Akt pathway. A) Using Akt-1 and Akt-2 null mice recently characterized by our lab, we will further elucidate the role of Akt signaling in the regulation of integrin activity. The role of Akt1/2 signaling in the regulation of integrin-dependent extracellular matrix expression and assembly will be determined. Since Akt1 influenced functions of numerous cell types involved in angiogenesis, we will define the role of endothelial Akt1 in angiogenesis. A detailed understanding of how successful collaboration occurs between an initiator of angiogenesis, VEGF, an effector system, the integrins, will create the basis for the development of novel therapeutic strategies in cardiology, vascular medicine and cancer treatment. PUBLIC HEALTH RELEVANCE: The major mechanism to adapt to regional ischemia resulting from myocardial infraction or peripheral vascular diseases is the development of new blood vessels, a process known as "angiogenesis". In cancer, inhibition of angiogenesis suppresses tumor growth. Angiogenesis is triggered by Vascular Endothelial Growth Factor and dependent on the functions of integrins receptors. In order to be able to "build" functional blood vessels or inhibit their formation, a detailed knowledge of the mechanisms of angiogenesis is required. The goal of this proposal is to assess the molecular and cellular mechanisms of angiogenesis with an emphasis on pathophysiologically relevant models.