MicroRNAs as Determinants of Endothelial Progenitor Cell Senescence

描述（由申请人提供）：微小RNA（miRNA）在调节干细胞和祖细胞的可塑性和功能方面发挥重要作用。衰老过程中miRNA表达模式以组织和基因特异性方式发生动态变化，提示特异性miRNA及其靶基因在介导内皮祖细胞（EPC）/谱系阴性骨髓细胞（linBMC）衰老变化和功能损伤中可能发挥作用。我们和其他人已经表明，EPC积极参与血管修复。衰老的EPC，如来自老年动物的EPC，具有受损的修复能力，这与动脉粥样硬化的发展相关联。因此，EPC衰老可能部分介导了衰老和其他心血管危险因素对动脉粥样硬化的强烈易感作用。为了确定在存在和不存在高胆固醇血症的情况下与年龄相关的EPC衰老的分子基础，我们对来自年轻和老年apoE/和野生型小鼠的EPC/linBMC进行了miRNA和mRNA分析。我们已经鉴定了miR10A */miR21、miR29c和miR126以及它们的靶基因在年轻和老年linBMC中差异表达。这些miRNA控制linBMC能力的不同方面。具体而言，miR10a */miR21hmga2p16Ink4a/p19Arf轴主要调节linBMC自我更新潜能，而miR29cklf2a轴主要调节linBMC自我更新潜能，miR126 spred1 VEGF信号传导主要控制linBMC分化能力。我们已经产生了支持miRNA在体内调节linBMC活性中的作用的证据。有了这个提议，我们已经开发了一套全面的实验来表征这两个候选途径在体外调节linBMC衰老中的联合作用。我们还将研究从我们的全基因组分析数据和已发表的报告中获得的其他miRNA/mRNA候选物。然后，我们将确定miR10a */miR21hmga2的功能意义。p16Ink4a/p19Arf轴和miR29c-klf2a-miR126spred1 VEGF信号传导以及其他候选miRNA及其靶基因（体外验证）在体内影响linBMC在apoE/小鼠血管修复和动脉粥样硬化发展中的有效性。这种综合和创新的方法将使我们能够彻底表征linBMC衰老和功能障碍的分子机制，这将有助于设计新的策略来减缓/逆转EPC/linBMC的衰老过程（从而降低动脉粥样硬化风险），并提高基于骨髓的细胞治疗动脉粥样硬化的疗效。

DESCRIPTION (provided by applicant): MicroRNAs (miRNA) play important roles in regulating the plasticity and functions of stem and progenitor cells. MiRNA expression pattern undergoes dynamic changes during aging in a tissue and gene specific manner, implicating a putative role of specific miRNA and their target genes in mediating senescent changes and functional impairment of endothelial progenitor cells (EPC)/lineage negative bone marrow cells (linBMC). We and others have shown that EPC are actively involved in vascular repair. Senescent EPC, such as those from aged animals, have impaired repair capacity, which is coupled with atherosclerosis development. Therefore, EPC senescence may partially mediate the strong predisposing effects of aging and other cardiovascular risk factors on atherosclerosis. To determine the molecular underpinnings for age associated EPC senescence in the presence and absence of percholesterolemia, we have performed miRNA and mRNA profiling in EPC/linBMC from young and aged apoE/ and wild type mice. We have identified miR10A*/ miR21, miR29c and miR126, as well as their target genes, to be differentially expressed in young and aged linBMC. These miRNA control distinct aspects of linBMC competency. Specifically, the miR10a*/ miR21hmga2p16Ink4a/p19Arf axis mainly regulates linBMC self renewal potential, whereas miR29cklf2amiR126 spred1 VEGF signaling predominantly governs linBMC differentiation capacity. We have generated evidence supporting the role of miRNA in regulating linBMC activities in vivo. With this proposal, we have developed a comprehensive set of experiments to characterize the combined effects of these two candidate pathways in regulating linBMC senescence in vitro. We will also study additional miRNA/mRNA candidates derived from analysis of our genome wide profiling data and published reports. Then, we will determine the functional significance of miR10a*/miR21hmga2-p16Ink4a/p19Arf axis and miR29c-klf2a-miR126spred1 VEGF signaling as well as additional candidate miRNA and their target genes (validated in vitro) in affecting the effectiveness of linBMC in vascular repair and atherosclerosis development in apoE/mice in vivo. This integrated and innovative approach will allow us to thoroughly characterize the molecular mechanisms underlying linBMC senescence and functional impairment, which will facilitate the design of novel strategies to slow down/reverse the senescent process of EPC/linBMC (therefore to reduce atherosclerosis risk) and to enhance the therapeutic efficacy of bone marrow based cellular treatments for atherosclerosis using genetic modifications.