Control Sterol and Lipoprotein Homeostasis by miRNA

 描述(申请人提供)：解除对脂代谢的管制是西方人群中一些最常见的医学疾病的基础，如心血管疾病、脂肪肝疾病、高脂血症和糖尿病。我们实验室的长期目标是获得 更好地了解生理、病理和药物刺激下全身脂肪的动态平衡。在上一个周期中，我们研究了他汀类药物诱导的小鼠miR-33对肝脏脂肪代谢、高密度脂蛋白和胆汁分泌、胆固醇反向运输和动脉粥样硬化形成的作用。目前的建议包括两组大的研究：第一，继续我们对miR-33的研究；第二，引入更多的他汀类诱导的miRNAs，并研究它们在肝脏代谢控制中的作用。在这项提案的前半部分，我们将使用一种新的肝脏人源化小鼠来继续我们目前资助的关于miR-33的研究。这些小鼠克服了传统小鼠模型的关键限制，恢复了肝脏人miR-33a和miR-33b、人miR-33靶标特异性和类人脂蛋白图谱。拟议的研究将提供关于治疗性沉默miR-33在人类功能肝脏中的后果的关键数据。另一方面，我们提供了他汀类药物在体内诱导小鼠肝脏RISCome(RNA诱导沉默复合体相关mRNAs)变化的证据。在这些变化中，我们聚焦于miR-183/96/182簇靶标TCF7L2，并提出了SREBP2-miR-183/96/182-TCF7L2途径在体内介导他汀类药物刺激的肝脏葡萄糖产生的证据。这一新的保守途径的翻译相关性通过最近描述的他汀类药物的糖尿病致病作用而增强。我们将使用生化、细胞生物学和活体技术的组合来测试这些新想法。具体地说，目标1将测试人肝脏miR-33a和miR-33b在肝脏脂代谢、脂蛋白分泌和动脉粥样硬化形成中的功能作用。重要的是，独特的肝脏人源化小鼠还将使我们能够首次测试miR-33b在饮食诱导的脂肪肝和肝脏胰岛素抵抗中的作用。目的2通过确定miR-183/96/182对肝脏和全身葡萄糖生成的贡献，明确miR簇和TCF7L2调节糖异生的机制，以及研究在血糖控制改变的小鼠模型中miR-183/96/182的水平及其功能靶点是否发生改变，从而确定miR-183/96/182在肝脏和全身葡萄糖动态平衡中的作用。这些研究的洞察力将填补目前在病理生理学肝脏代谢控制方面的知识空白，并可能发现管理肝脏疾病、糖尿病和心血管风险的新药理靶点。

 DESCRIPTION (provided by applicant): Deregulation of lipid metabolism is the basis of some of the most common medical disorders in western populations, such as cardiovascular disease, fatty liver diseases, hyperlipidemia, and diabetes. The long-term goal in our laboratory is to gain a better understanding of whole-body lipid homeostasis in response to physiological, pathological, and pharmacological stimuli. In the previous cycle, we studied the role of the statin-induced murine miR-33 on hepatic lipid metabolism, HDL and bile secretion, reverse cholesterol transport, and atherogenesis. The current proposal includes two large sets of studies: first, to continue our studies on miR-33; and second, to introduce additional statin-induced miRNAs and study their role on hepatic metabolic control. In the first half of this proposal, we will use a novel liver-humanized mouse to continue our currently funded studies on miR-33. These mice overcome the critical limitations of traditional murine models, restoring hepatic human miR-33a and miR-33b, human miR-33 target specificity, and human-like lipoprotein profiles. The proposed studies will provide critical data on the consequences of therapeutic silencing of miR-33 in a human, functional liver. On the other hand, we present evidence that statins induce changes in the murine hepatic RISCome (RNA-induced silencing complex-associated mRNAs) in vivo. Among these changes, we focus on the miR-183/96/182 cluster target TCF7L2, and present evidence that the SREBP2-miR-183/96/182-TCF7L2 pathway mediates statin-stimulated hepatic glucose production in vivo. The translational relevance of this new conserved pathway is enhanced by the recently described diabetogenic effect of statins. We will test these new ideas using a combination of biochemical, cell biology, and in vivo techniques. Specifically, Aim 1 will test the functional role of human hepatic miR-33a and miR-33b on hepatic lipid metabolism, lipoprotein secretion, and atherogenesis. Importantly, the unique liver-humanized mice will also allow us to test for the first time the contribution of miR-33b to diet-induced fatty liver and hepatic insulin resistance. Aim 2 will define the functiona role of miR-183/96/182 on hepatic and whole-body glucose homeostasis, by determining the contribution of each miR to hepatic glucose production, defining the mechanism by which the miR cluster and TCF7L2 regulate gluconeogenesis, and studying whether the levels of miR-183/96/182 and their functional targets are altered in murine models of altered glycemic control. The insights from these studies will fill a current gap of knowledge in pathophysiological hepatic metabolic control, and may uncover novel pharmacological targets to manage liver diseases, diabetes, and cardiovascular risk.