The AMP-activated protein kinase (AMPK) antagonizes inflammation through SIRT1

描述（由申请人提供）：炎症通路的激活将肥胖与胰岛素抵抗联系起来。肥胖症中的炎症信号传导途径可以被过量的营养素（例如脂质）激活。然而，过量的营养物质如何在细胞内被感知并改变炎症程序是完全理解的。可能介导这一过程的两种信号蛋白是两种营养传感器：AMPK活化蛋白激酶（AMPK）和SIRT。AMPK作为细胞能量计发挥作用，调节脂质和葡萄糖代谢中的代谢途径。SIRT 1也是一种能量传感器，是一种NAD+依赖性脱乙酰酶，介导热量限制延长寿命的作用。AMPK和SIRT 1在感知营养供应和调节代谢途径方面表现出惊人的相似性，并且可能相互作用以执行这些功能。新的证据表明AMPK和SIRT 1也调节炎症信号。我们的初步数据表明：（1）AMPK和SIRT 1信号转导和表达在巨噬细胞和脂肪组织中在诱发炎症的条件下下调，如暴露于脂多糖（LPS）、游离脂肪酸（FFA）和饮食诱导的肥胖;（2）AMPK和SIRT 1的激活防止了巨噬细胞中LPS和FFA诱导的炎症;（3）AMPK的激活刺激SIRT 1活性并诱导SIRT 1表达。我们的总体假设是AMPK和SIRT 1作为炎症信号事件的关键决定因素，AMPK和SIRT 1合作调节肥胖症的炎症和胰岛素抵抗。具体目标1将确定AMPK对FFA诱导的巨噬细胞炎症的保护作用。我们将研究LPS和FFA攻击的巨噬细胞中AMPK信号功能丧失或获得的炎症信号。具体目标2将确定巨噬细胞中AMPK的失活是否促进饮食诱导的肥胖小鼠的炎症和胰岛素抵抗。我们将进行骨髓移植以产生具有α 1AMPK缺陷的巨噬细胞的小鼠，并将表征这些小鼠的炎症状态和胰岛素敏感性，这些小鼠喂食高脂饮食或输注脂质。具体目标3将确定SIRT 1是否介导AMPK对FFA诱导的巨噬细胞炎症的保护作用。我们将研究SIRT 1功能丧失或获得与AMPK功能获得或丧失配对的巨噬细胞中的炎症信号通路。我们还将在巨噬细胞中产生SIRT 1缺陷的小鼠模型，并评估用HF饮食治疗的这些小鼠的炎症和胰岛素敏感性。该项目将AMPK和SIRT 1定义为脂质诱导的炎症的负调节因子，以及这些蛋白质在弥合营养代谢和炎症之间的信号传导间隙中的新作用。该项目的发现将导致AMPK和SIRT 1作为治疗肥胖诱导的炎症和胰岛素抵抗的新治疗靶点的发展。公共卫生相关性：本课题的目的是研究AMPK和SIRT在肥胖症炎症和胰岛素抵抗中的作用及其相互作用。该项目的发现将导致AMPK和SIRT 1作为治疗肥胖诱导的炎症和胰岛素抵抗的新治疗靶点的发展。

DESCRIPTION (provided by applicant): Activation of inflammatory pathways links obesity to insulin resistance. Inflammatory signaling pathways in obesity can be activated by excess nutrients (e.g. lipids). However, how excess nutrients are sensed within the cells and alter inflammatory program is fully understood. Two signaling proteins that may mediate this process are the two nutrient sensors: AMPK-activated protein kinase (AMPK) and SIRT. AMPK functions as a cellular energy gauge that regulates metabolic pathways in lipid and glucose metabolism. SIRT1, which also functions as an energy sensor, is an NAD+dependent deacetylase that mediates the effects of caloric restriction to extend longevity. AMPK and SIRT1 show striking similarities in sensing nutrient supply and regulating metabolic pathways and are likely to interact to perform these functions. Emerging evidence suggests that both AMPK and SIRT1 also regulate inflammatory signaling. Our preliminary data suggested that (1) AMPK and SIRT1 signaling and expression in macrophages and adipose tissue are down-regulated in conditions that evoke inflammation, such as exposure to lipopolysaccharide (LPS), free fatty acids (FFA), and diet-induced obesity; (2) activation of AMPK and SIRT1 prevents LPS- and FFA-induced inflammation in macrophages; (3) activation of AMPK stimulates SIRT1 activity and induces SIRT1 expression. Our overall hypothesis is that AMPK and SIRT1 serve as key determinants of inflammatory signaling events and AMPK and SIRT1 cooperate to regulate inflammation and insulin resistance in obesity. Specific Aim 1 will determine the protective effects of AMPK against FFA-induced inflammation in macrophages. We will examine the inflammatory signaling in LPS- and FFA-challenged macrophage with loss or gain of function of AMPK signaling. Specific Aim 2 will determine whether inactivation of AMPK in macrophages promotes inflammation and insulin resistance in diet-induced obese mice. We will perform bone marrow transplantation to generate mice with alpha1AMPK-deficient macrophages, and will characterize the inflammatory status and insulin sensitivity in these mice fed a high-fat diet or infused with lipids. Specific Aim 3 will determine whether SIRT1 mediates the protective effects of AMPK against FFA-induced inflammation in macrophages. We will examine the inflammatory signaling pathways in macrophages with loss or gain of function of SIRT1 paired with gain or loss of function of AMPK. We will also generate a mouse model deficient in SIRT1 in macrophages and assess inflammation and insulin sensitivity in these mice treated with a HF diet. This project will define AMPK and SIRT1 as negative regulators of lipid-induced inflammation and the novel roles of these proteins in bridging the signaling gap between nutrient metabolism and inflammation. The findings from this project will lead to the development of AMPK and SIRT1 as new therapeutic targets in treatment of obesity-induced inflammation and insulin resistance. PUBLIC HEALTH RELEVANCE: This goal of this project is to study the roles of AMPK and SIRT and their interaction in regulating inflammation and insulin resistance in obesity. The findings from this project will lead to the development of AMPK and SIRT1 as new therapeutic targets in treatment of obesity-induced inflammation and insulin resistance.