Role of miR-145 in Vascular Smooth Muscle Cell BiologyRole of

描述（由申请人提供）：miR-145在血管平滑肌细胞生物学中的作用MicroRNA （miRNA）已经成为一类新型的内源性小非编码rna，通过降解或翻译抑制靶mrna对细胞中超过30%的基因进行负调控。在功能上，单个miRNA作为转录因子是重要的，因为它能够调节其多个靶基因的表达。因此，mirna参与所有主要细胞功能的调控，如细胞分化、增殖和迁移，就不足为奇了。最近，我们发现microRNA-145 （miR-145）是血管平滑肌细胞（VSMCs）中最丰富的miRNA，在体内新生内膜病变形成的血管壁VSMCs和体外培养的去分化VSMCs中，其表达显著下调。然而，miR-145在VSMC生物学中的作用目前尚不清楚。已经证实，VSMCs从分化表型向去分化状态的转变，伴随着迁移和增殖的加速，在动脉粥样硬化、再狭窄等多种增殖性血管疾病的发病机制中起着关键作用。我们的长期目标是确定mirna在VSMC生物学中的作用及其对增殖性血管疾病的贡献。本研究的目的是确定miR-145在VSMC表型调节、增殖、迁移和血管内膜病变形成中的作用，并阐明其分子机制。我们的中心假设是miR-145是VSMC表型、增殖、迁移、血管新生内膜生长和动脉粥样硬化病变形成的关键调节剂，通过其靶基因，kruppel样因子5 （KLF5）和kruppel样因子4 （KLF4）。我们的假设得到了初步研究的支持。我们将通过以下四个具体目的进一步验证我们的假设：目的1是确定miR-145在体外培养VSMC的表型调节、增殖和迁移中的作用。目的2是确定miR-145在损伤大鼠颈动脉内VSMC表型调节、增殖、迁移和血管新生内膜生长中的作用。目的3是在载脂蛋白E敲除小鼠中确定miR-145在动脉粥样硬化病变形成中的作用及其细胞机制。目的4是阐明mir -145介导的对VSMC表型、增殖、迁移以及血管内膜和动脉粥样硬化病变形成的影响的分子机制。这些目标将通过利用最新的细胞、分子和全动物方法来实现，包括转基因和基因敲除小鼠。目前的提案将确定一种全新的VSMC表型、增殖、迁移和血管内膜和动脉粥样硬化病变形成的调节剂。来自这一创新研究领域的这些发现可能对各种增殖性血管疾病的诊断和治疗具有广泛的意义，如动脉粥样硬化、高血压、血管成形术或搭桥后再狭窄、糖尿病血管并发症和移植动脉病变。

DESCRIPTION (provided by applicant): Role of miR-145 in Vascular Smooth Muscle Cell Biology MicroRNA (miRNA) have emerged as a novel class of endogenous, small, noncoding RNAs that negatively regulate over 30% of genes in a cell via degradation or translational inhibition of their target mRNAs. Functionally, an individual miRNA is important as a transcription factor because it is able to regulate the expression of its multiple target genes. It is therefore not surprising that miRNAs are involved in the regulation of all major cellular functions such as cell differentiation, proliferation and migration. Recently, we have found that microRNA-145 (miR-145) is the most abundant miRNA in vascular smooth muscle cells (VSMCs) and its expression is significantly downregulated in VSMCs of vascular walls with neointimal lesion formation in vivo and in cultured dedifferentiated VSMCs in vitro. However, the role of miR-145 in the VSMC biology is currently unclear. It is well established that the transition of VSMCs from a differentiated phenotype to a dedifferentiated state, which is accompanied by accelerated migration and proliferation, plays a critical role in the pathogenesis of a variety of proliferative vascular diseases such as atherosclerosis and restenosis. Our long-term goals are to determine the roles of miRNAs in VSMC biology and their contribution to proliferative vascular diseases. The goal of this proposal is to determine the role of miR-145 in VSMC phenotypic modulation, proliferation, migration and vascular neointimal lesion formation, and to elucidate the molecular mechanisms involved. Our central hypothesis is that miR-145 is a critical modulator for VSMC phenotype, proliferation, migration, vascular neointimal growth and atherosclerotic lesion formation via its target genes, kruppel-like factor 5 (KLF5) and kruppel-like factor 4 (KLF4). Our hypothesis is supported by our preliminary studies. We will further test our hypothesis by the following four specific aims: Aim 1 is to determine the roles of miR-145 in VSMC phenotypic modulation, proliferation, and migration in cultured VSMCs in vitro. Aim 2 is to determine the roles of miR-145 in VSMC phenotypic modulation, proliferation, migration, and vascular neointimal growth in injured rat carotid arteries in vivo. Aim 3 is to determine the role of miR-145 in atherosclerotic lesion formation and its cellular mechanisms in Apo E knockout mice. Aim 4 is to elucidate the molecular mechanisms that are responsible for miR-145-mediated effects on VSMC phenotype, proliferation, migration and vascular neointimal and atherosclerotic lesion formation. These aims will be accomplished by utilizing the latest cellular, molecular, and whole animal approaches including transgenic and gene knockout mice. The current proposal will identify an entirely new regulator for VSMC phenotype, proliferation, migration and vascular neointimal and atherosclerotic lesion formation. These findings from this innovative research area may have extensive implications for the diagnosis and treatment of a variety of proliferative vascular diseases, such as atherosclerosis, hypertension, restenosis after angioplasty or bypass, diabetic vascular complications, and transplantation arteriopathy. PUBLIC HEALTH RELEVANCE: MicroRNA-145 (miR-145) is the most abundant microRNA in vascular smooth muscle cells (VSMCs) and its expression is significantly downregulated in VSMCs of vascular walls with neointimal lesion formation in vivo and in cultured dedifferentiated VSMCs in vitro. However, the role of miR-145 in the VSMC biology and its potential contribution in the development of vascular disease are unclear. The goal of this project is to determine the role of miR-145 in VSMC biology and vascular neointimal lesion formation and to elucidate the molecular mechanisms involved.