RNA-Mediated Inter-Organelle Communication in Atherosclerosis

项目摘要 缺血性心血管疾病是由动脉粥样硬化引起的一种脂质驱动的炎症性疾病 影响动脉，可发展成易损斑块和血栓性闭塞。的精确 将营养过剩和高脂血症与免疫激活联系起来的分子机制仍然难以捉摸， 这些机制的发现可能导致新的CVD治疗。一个重要的入门， 血脂异常中的炎症是慢性代谢超负荷和合成代谢受损， 分解代谢细胞器细胞器应激的减少会导致胰岛素抵抗和动脉粥样硬化。 最近，我们发现肌醇需要酶-1（IRE 1）的小分子抑制剂， 压力传感器，对抗动脉粥样硬化进展。ER膜还充当成核位点 RNA诱导沉默复合物（RISC），我们有了惊人的发现， 磷酸化双链RNA结合蛋白，蛋白激酶R的蛋白激活剂 （PACT），与RISC相关联。我们发现脂质应激诱导IRE 1磷酸化PACT， 抑制线粒体生物发生（mito-biogenesis），部分通过控制miRNA（miR）-181c。 稳态机制，如线粒体自噬（去除）或线粒体生物合成（补充）功能障碍 线粒体可以对抗炎症，也可以在动脉粥样硬化斑块细胞中起作用。异常活化 脂质介导的IRE 1-PACT信号传导阻断线粒体生物合成并传播线粒体氧化（MOX）应激 和炎症，表明抑制这种病理信号可以对抗动脉粥样硬化。公约 与人类2号染色体上与早发冠状动脉疾病有关的基因座相邻， 血浆HDL-C水平。PACT表达在动脉粥样硬化进展过程中被诱导， 小鼠的退化我们假设抑制IRE 1-PACT信号传导将促进有丝分裂生物合成 并对抗炎症和动脉粥样硬化。我们将阐明PACT如何调节有丝分裂生物合成， 发现与有丝分裂生物发生调控相关的PACT的miR靶标及其RNA靶标。我们 发现的miR-181 c是这些PACT靶点之一，可以阻断有丝分裂生物发生。我们将直接调查 PACT和miR-181 c对高脂血症诱导有丝分裂生物发生、炎症和动脉粥样硬化影响 in vivo.基于发现的靶点（针对miR-181 c和其他靶点），我们将开发更具体的 治疗性靶向方法（使用锁核酸靶位点阻断剂）以消融miR和靶向 动脉粥样硬化小鼠的相互作用。这些研究的成功完成将有助于确定 ER和线粒体之间前所未有的免疫代谢串扰机制， 高脂血症可促进MOX应激、炎症和动脉粥样硬化。理解内在的 在动脉粥样硬化形成过程中，这种RNA介导的细胞器间通讯的运作可以为动脉粥样硬化的发生铺平道路。 新的治疗方法，针对这种特定的免疫代谢串扰在CVD的方式。

PROJECT ABSTRACT Ischemic cardiovascular disease (CVD) is caused by atherosclerosis, a lipid-driven inflammatory disease affecting the arteries, which can progress into vulnerable plaques and thrombotic occlusion. The precise molecular mechanisms linking nutrient excess and hyperlipidemia to immune activation remains elusive and the discovery of these mechanisms could lead to novel CVD therapeutics. An important primer for inflammation in dyslipidemia is the chronic metabolic overloading and impairment of anabolic and catabolic organelles. Reduction of organelle stress alleviates insulin resistance and atherosclerosis. Recently, we showed that small molecule inhibitors of Inositol-requiring enzyme -1 (IRE1), a proximal ER stress sensor, counteract atherosclerosis progression. The ER membranes also serve as a nucleation site for RNA-induced silencing complex (RISC), and we made the striking discovery that IRE1 kinase phosphorylates the double stranded RNA-binding protein, the protein activator of the protein kinase R (PACT), that associates with RISC. We found lipid stress induces IRE1 to phosphorylate PACT, which suppresses mitochondrial biogenesis (mito-biogenesis), in part by controlling a miRNA (miR)-181c. Homeostatic mechanisms such as mitophagy (to remove) or mito-biogenesis (to replenish) the malfunctioning mitochondria can counteract inflammation and also operate in atherosclerotic plaque cells. Aberrant activation of IRE1-PACT signaling by lipids block mito-biogenesis and propagate mitochondrial oxidative (MOX) stress and inflammation, indicating inhibition of this pathological signaling could counteract atherosclerosis. PACT is proximal to a locus on human chromosome 2 that is linked to premature coronary artery disease and plasma HDL-C levels. PACT expression is induced during atherosclerosis progression and reduced during regression in mice. We hypothesize that suppressing IRE1-PACT signaling will promote mito-biogenesis and counteract inflammation and atherosclerosis. We will elucidate how PACT regulates mito-biogenesis by discovering PACT’s miR target(s) and their RNA targets that are relevant to mito-biogenesis regulation. We discovered miR-181c is one of these PACT targets that blocks mito-biogenesis. We will directly investigate the impact of PACT and miR-181c on hyperlipidemia-induced mito-biogenesis, inflammation and atherosclerosis in vivo. Based on the discovered targets (for miR-181c and others) we will develop a more specific therapeutic targeting approach (using Locked Nucleic Acid-Target-Site Blockers) to ablate miR and target interaction in atherosclerotic mice. The successful completion of these studies will help define an unprecedented mechanism of immune-metabolic crosstalk between ER and mitochondria by which hyperlipidemia can promote MOX stress, inflammation and atherosclerosis. Understanding the intrinsic operation of this RNA-mediated inter-organelle communication during atherogenesis could pave the way for novel therapeutic approaches targeting this specific immune-metabolic cross talk in CVD.