Notch1/miR-322 Axis in Stem Cell Mediated Vascular Repair

项目总结 心脏间充质干细胞(C-MSC)是存在于心脏中的一种独特的干细胞库 在血管内稳态和生理血管细胞周转中起重要作用。 将C-MSC移植到心脏显示出在血管修复和血管生成方面的前景， 但移植细胞存活率低是一个重大的技术挑战。我们报道了 低氧预适应(HP)改善HIF-1α中供体干细胞存活和血管生成 依赖的态度。从机制上讲，C-MSC对幽门螺杆菌的反应与 Notch信号的激活，这是干细胞中的一种细胞-细胞接触和途径，也是介导 C-MSC的血管平滑肌细胞(VSMC)分化。此外，我们还确定了一种 缺口调节的microRNA，miR-322，人类miR-424的啮齿动物同源物，它是 据报道通过阻断人缺氧诱导因子-1α亚型的降解来促进血管生成 提示了一种新的Notch-Notch之间串扰机制。 调节miR-322和HIF-1α。我们建议调查Notch-1和新的 确定的Notch-1靶点miR-322维持和增强HP对 干细胞的血管细胞存活和血管生成活性。我们还将确定是否 利用干细胞中的这些调节机制可以增强血管保护和 心肌梗死(MI)小鼠模型的修复。有三个目标：目标1：测试 Notch信号调节幽门螺杆菌在干细胞介导的有益作用的假说 血管修复。目的2：验证miR-322介导Notch1之间串扰的假设 以及HIF-1α信号在干细胞中的作用，以增强其活性。目标3：测试治疗方法 靶向Notch1/miR-322轴促进干细胞介导的血管修复的可能性 以及心肌梗死小鼠模型中的血管生成。成功完成拟议的研究将 阐明与C-MSC介导的血管修复相关的新机制 促进血管生成，提高C-MSC治疗效果。

PROJECT SUMMARY Cardiac mesenchymal stem cells (C-MSC) are a unique pool of stem cells residing in the heart that play an important role in vascular homeostasis and physiological vascular cell turnover. Transplanting C-MSC into the heart has shown promise for vessel repair and angiogenesis, but poor survival of transplanted cells poses a major technical challenge. We reported that hypoxic preconditioning (HP) improves donor stem cell survival and angiogenesis in a HIF-1α- dependent manner. Mechanistically, C-MSC responses to HP correlate with the level of activation of Notch signaling, a cell-cell contact and pathway in stem cells that also mediates vascular smooth muscle cell (VSMC) differentiation of C-MSC. Moreover, we have identified a Notch-regulated microRNA, miR-322, the rodent homolog of human miR-424, which was reported to promote angiogenesis by blocking degradation of HIF-1α isoforms in human endothelial cells during hypoxia, suggesting a novel mechanism of crosstalk between Notch- regulated miR-322 and HIF-1α. We propose to investigate how Notch-1 and the newly identified Notch-1 target miR-322 sustain and potentiate the beneficial effects of HP on the vascular cell survival and angiogenic activity of stem cells. We will also determine whether harnessing these regulatory mechanisms in stem cells can enhance vessel protection and repair in a mouse model of myocardial infarction (MI). There are three aims: Aim 1: Test the hypothesis that Notch signaling regulates the beneficial effects of HP in stem cell-mediated vascular repair. Aim 2: Test the hypothesis that miR-322 mediates crosstalk between Notch1 and HIF-1α signaling in stem cells to enhance their activity. Aim 3: Test the therapeutic potential of targeting the Notch1/miR-322 axis to enhance stem cell-mediated vascular repair and angiogenesis in a mouse model of MI. Successful completion of the proposed studies will elucidate novel mechanisms associated with C-MSC mediated vascular repair and angiogenesis and enhance the efficacy of C-MSC therapy.