Transcriptional control of microRNAs in lipid metabolism and atherosclerosis

 描述(由申请人提供)：胆固醇失衡在多种疾病中起着核心作用，特别是心血管疾病，也是美国的主要死亡原因。脂质负载的巨噬细胞泡沫细胞是动脉粥样硬化发病机制中的关键决定因素。MicroRNAs是一种小的非编码RNA分子，调节胆固醇和脂蛋白代谢，可能对疾病的进展起到重要作用。我们发现miR-144是一种新的脂代谢调节剂，也受核受体法尼醇X受体(FXR)的调节。我们确定胆固醇转运体ABCA1是miR-144的靶基因，并表明miR-144在肝脏的表达增加会降低ABCA1蛋白和血浆胆固醇水平。因此，我们假设沉默miR-144可能具有治疗潜力，因为首先，它会增加动脉粥样硬化保护性高密度脂蛋白颗粒的水平；其次，它可能会由于巨噬细胞中ABCA1水平的增加而增强胆固醇的反向转运(RCT)。在目前的提案中，我们现在证明了沉默miR-144具有动脉粥样硬化保护作用。在特定的目标1中，我们通过EN Face分析在回归模型中展示了在LDLR-/-小鼠中沉默miR-144具有动脉粥样硬化保护作用的初步数据。我们现在将详细描述多个血管的动脉粥样硬化病变，并确定延长miR-144的沉默是否进一步促进动脉粥样硬化的消退。在特定的目标2中，我们展示了沉默miR-144延缓LDLR-/-小鼠动脉粥样硬化进展的初步分析。我们现在将对病变进行详细的分析，并确定沉默miR-144是否对另一种动脉粥样硬化疾病模型也具有保护作用。最后，在特定的目标3中，我们将确定沉默miR-144的动脉粥样硬化保护作用的分子机制。我们将确定miR-144沉默是否增强RCT，改变高密度脂蛋白的特性，并影响病变内巨噬细胞和肝脏中的全球基因网络。因此，我们的建议将确定沉默miR-144的动脉粥样硬化保护作用的分子基础，并将这一途径确立为治疗动脉粥样硬化的真正策略。

 DESCRIPTION (provided by applicant): Cholesterol imbalance plays a central role in multiple diseases, particularly cardiovascular disease, and the leading cause of death in the United States. Lipid-loaded macrophage foam cells are a critical determining factor in the pathogenesis of atherosclerosis. MicroRNAs are small non-coding RNA molecules that regulate both cholesterol and lipoprotein metabolism, and may significantly contribute to disease progression. We identified miR-144 as a novel regulator of lipid metabolism that is also regulated by the nuclear receptor farnesoid X receptor (FXR). We identified the cholesterol transporter ABCA1 as a miR-144 target gene, and showed that increased hepatic expression of miR-144 decreased ABCA1 protein and plasma cholesterol levels. Consequently, we hypothesized that silencing miR-144 may have therapeutic potential because, first it would increase the levels of atheroprotective HDL particles; and secondly, it may enhance reverse cholesterol transport (RCT) due to increased ABCA1 levels in macrophages. In the current proposal we now demonstrate that silencing miR-144 is atheroprotective. In Specific Aim 1, we show preliminary data where silencing miR- 144 in Ldlr-/- mice is atheroprotective in a regression model by en face analysis. We will now characterize atherosclerotic lesions in multiple vessels in detail, and determine whether prolonged silencing of miR-144 further enhances regression of atherosclerosis. In Specific Aim 2, we show preliminary analysis where silencing miR-144 attenuates progression of atherosclerosis in Ldlr-/- mice. We will now carry out detailed analysis of the lesions, and determine whether silencing miR-144 is also protective in a different model of atherosclerosis disease. Finally, in Specific Aim 3, we will determine the molecular mechanism that underlies the atheroprotective effects of silencing miR-144. We will determine whether miR-144 silencing enhances RCT, alters HDL properties and affects global gene networks in both macrophages within lesions and liver. Thus, our proposal will determine the molecular basis for the atheroprotective effects of silencing miR-144, and establish this pathway as a bona-fide strategy to treat atherosclerosis.