MicroRNA regulation of RasGAP's during angiogenesis

描述（由申请人提供）：血管生成是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，血管生成是一系列可控的事件，导致血管重塑，以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起作用，允许最初的发芽和入侵，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，通常导致血管组织不良，具有泄漏和弯曲的特性。血管生成最终由促血管生成因子和抗血管生成因子的平衡控制，这些因子调节基质和血管细胞的募集和激活。在这里，我们已经确定了一种新的途径，其中促血管生成的microRNA破坏了抗血管生成信号分子的表达。MicroRNAs是具有阻断靶基因表达能力的短核苷酸序列。我们已经确定miR-132是一种在稳定的静止血管中不表达的microRNA，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的表达足以驱动血管发芽和增殖，而抑制miR-132则会阻断生长因子诱导的血管生成。因此，我们已经证明miR-132作为一种促血管生成因子，可以激活内皮细胞。此外，我们已经确定了RasGAP家族成员p120RasGAP作为miR-132的主要靶基因。在Aim 1中，我们将评估p120RasGAP活性对ras依赖性和ras非依赖性信号传导的贡献，并确定p120RasGAP的表达是否可能在血管生成过程中被额外的miRs调节。在Aim 2中，我们将描述RasGAP同源物在内皮细胞中的表达和作用，并确定它们是否也可能在血管生成过程中受到miR的调控。这项工作的长期目标和临床应用是评估靶向RasGAP家族成员的抗mirs作为抗血管生成治疗因血管增殖而加剧的疾病的应用（目的3）。总之，这些研究将提供RasGAPs在血管生成过程中的作用，并建立分子基础，以支持抗mir治疗作为血管增殖性疾病患者的抗血管生成策略的发展。

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.