MicroRNA regulation of RasGAP's during angiogenesis

描述(申请人提供)：血管生成是指现有血管发芽形成新血管的过程。在成人的发育和一些生理事件中，血管生成是一系列受控的事件，导致血管重塑，支持不断变化的组织需求。许多促血管生成因子和抗血管生成因子在平衡中发挥作用，允许最初的萌发和侵袭，随后的修剪和重塑，最后成熟和存活。然而，在病理情况下，如癌症，相同的血管生成信号通路被诱导和利用，典型地导致组织不良的血管具有泄漏和曲折的性质。血管生成最终由调节基质细胞和血管细胞的招募和激活的促血管生成因子和抗血管生成因子的平衡控制。在这里，我们已经确定了一条新的途径，在该途径中，促进血管生成的microRNA干扰了反血管生成信号分子的表达。MicroRNAs是一种短核苷酸序列，具有阻断靶基因表达的能力。我们发现miR-132是一种微RNA，在稳定的静止血管中不表达，但在血管生成组织和受生长因子刺激的内皮细胞中表达上调。在缺乏生长因子的情况下，miR-132的表达足以促进血管的萌发和增殖，而抑制miR-132则阻断生长因子诱导的血管生成。因此，我们已经证明miR-132是一种促血管生成因子，可以激活内皮细胞。此外，我们还确定了RasGAP家族成员p120RasGAP是miR-132的主要靶基因。在目标1中，我们将评估p120RasGAP活性在RAS依赖和RAS非依赖性信号转导中的作用，并确定在血管生成过程中p120RasGAP的表达是否可能受到额外的miRs的调节。在目标2中，我们将表征RasGAP同源物在血管内皮细胞中的表达和作用，并确定这些同源物在血管生成过程中是否也受到miR的调控。这项工作的长期目标和临床应用是评估针对RasGAP家族成员的抗miRs作为抗血管生成疗法在因血管增殖而加剧的疾病中的使用(目标3)。总之，这些研究将深入了解RasGAP在血管生成中的作用，并建立分子基础，支持将抗miR治疗作为血管增生性疾病患者的抗血管生成策略。

DESCRIPTION (provided by applicant): Angiogenesis is the process by which existing blood vessels sprout to form new vessels. During development and some physiological events in the adult, angiogenesis occurs as a controlled series of events leading to vascular remodeling that supports changing tissue requirements. A host of pro- and anti-angiogenic factors work in a balance to allow initial sprouting and invasion, subsequent pruning and remodeling, and finally maturation and survival. However, in pathological situations such as cancer, the same angiogenic signaling pathways are induced and exploited, typically resulting in poorly organized vessels with leaky and tortuous properties. Angiogenesis is ultimately controlled by a balance of pro- and anti-angiogenic factors that regulate the recruitment and activation of stromal and vascular cells. Here, we have identified a novel pathway in which a pro-angiogenic microRNA disrupts the expression of an anti-angiogenic signaling molecule. MicroRNAs are short nucleotide sequences that have the ability to block expression of target genes. We have identified miR-132 as a microRNA which is not expressed in stable quiescent vessels, but which is upregulated in angiogenic tissues and in endothelial cells stimulated with growth factors. Expression of miR-132 is sufficient to drive vascular sprouting and proliferation in the absence of growth factors, whereas inhibition of miR-132 blocks growth factor-induced angiogenesis. Thus, we have shown that miR-132 functions as a pro-angiogenic factor which can activate endothelial cells. Furthermore, we have identified a RasGAP family member, p120RasGAP, as a primary target gene of miR-132. In Aim 1, we will evaluate the contribution of p120RasGAP activity to Ras-dependent and Ras-independent signaling, and determine whether the expression of p120RasGAP may be modulated by additional miRs during angiogenesis. In Aim 2, we will characterize the expression and role of RasGAP homologs in endothelial cells, and identify whether these may also be subject to miR regulation during angiogenesis. The long-term objective and clinical application of this work is to evaluate the use of anti-miRs targeting RasGAP family members as anti-angiogenic therapies for diseases that are exacerbated by vascular proliferation (Aim 3). Together, these studies will provide insight into the role of RasGAPs during angiogenesis and establish a molecular basis to support the development of anti-miR therapy as an anti-angiogenic strategy for patients with vascular proliferative disease.