Extracellular Matrix as a Solid-State Regulator During Angiogenesis

这一更新建议的总体目标是了解通过 细胞外基质(ECM)在肿瘤发展过程中调节血管生成，特别关注如何 毛细血管内皮细胞与其ECM黏附的物理相互作用控制定向细胞 能动性。在上一次授予期间，我们展示了细胞-ECM界面的机械变化 单元移动的方向，因为物理力分布的局部变化决定了单元的位置 在可溶性运动的刺激下，会形成局灶性粘连(FA)并延伸新的运动过程 各种因素。对这种运动性转向机构和FA重新定位机构的分析表明， 跨膜整合素受体传递机械力的中心作用 反应，进而激活额外的p1整合素受体。其他信号分子，包括 小的GTP酶Rho和Rac也参与了ECM影响FA定位的机制，以及 缺乏FA蛋白Paxlin的细胞不能显示FA形成和片状脂体之间的空间耦合 分机。在单独的研究中，我们发现Rho的上游调控因子p190RhoGAP可能与 细胞骨架通过另一种机制向细胞运动和血管生成发出信号：这种Rho抑制剂调节 转录因子TFII-I的活性，从而控制血管内皮细胞的表达 生长因子受体VEGFR2。因此，具体目标包括：1)探索压力如何-- 依赖激活(31整合素和Rho改变焦点粘连位置，2)以确定焦点如何 粘连支配板脂定位和细胞定向迁移，以及3)分析细胞骨架是如何 P190RhoGAP信号转导影响VEGFR2基因表达。这些研究将包括体外试验 在肿瘤血管生成模型中的机制实验和体内研究以确定潜在的 我们发现的临床相关性。 了解控制方向迁移的机械信号反应的分子基础 毛细血管细胞的研究可为治疗干预寻找新的分子靶点 几乎在所有需要持续血管生成才能生长和扩张的实体癌症中。

The general goal of this renewal proposal is to understand the biomechanical mechanism by which extracellular matrix (ECM) regulates angiogenesis during tumor development, with a specific focus on how physical interactions between capillary endothelial (CE) cells and their ECM adhesions control directional cell motility. During the last grant period, we showed that mechanical changes at the cell-ECM interface govern the direction in which cells move because local variations of physical force distributions dictate where cells will form focal adhesions (FAs) and extend new motile processes when stimulated with soluble motility factors. Analysis of this motility steering mechanism and the mechanism of FA repositioning revealed a central role for transfer of mechanical forces across transmembrane integrin receptors which elicit signaling responses that, in turn, activate additional p1 integrin receptors. Other signaling molecules, including the small GTPases, Rho and Rac, also contribute to the mechanism by which ECM influences FA location, and cells that lack the FA protein paxillin fail to exhibit spatial coupling between FA formation and lamellipodia extension. In separate studies, we discovered that an upstream regulator of Rho, p190RhoGAP, may link cytoskeletal signaling to cell motility and angiogenesis by another mechanism: this Rho inhibitor regulates the activity of the transcription factor TFII-I and thereby controls expression of the vascular endothelial growth factor (VEGF) receptor VEGFR2. Thus, the specific aims include: 1) To explore how stress- dependent activation of (31 integrin and Rho alter focal adhesion position, 2) To determine how focal adhesions govern lamellipodia positioning and directional cell migration, and 3) To analyze how cytoskeletal signaling through p190RhoGAP influences VEGFR2 gene expression. These studies will include in vitro mechanistic experiments as well as in vivo studies in a tumor angiogenesis model to determine the potential clinical relevance of our findings. Understanding the molecular basis of this mechanical signaling response that controls direction migration of capillary blood vessel cells could lead to identification of new molecular targets for therapeutic intervention in virtually all solid cancers that require continuous angiogenesis for their own growth and expansion.