Cross-regulation of Immunometabolism and Circadian Pathways in Obesity Pathophysiology

项目摘要 肥胖和糖尿病在倒班、睡眠减少和社交时差的个体中增加。 高脂饮食(HFD)使固有的昼夜节律周期与明/暗周期不一致，并改变代谢的振荡 内脏脂肪组织中的基因，它是控制能量平衡、葡萄糖调节和炎症的关键部位 精神错乱。相反，将HFD限制在黑暗时期只会重新调整进食时间与昼夜节律和 增强胰岛素敏感性，促进健康肥胖。内脏脂肪组织的昼夜节律紊乱 导致肥胖的病理生理学机制尚不清楚。在令人兴奋的新数据中，我们展示了强劲的昼夜 脂肪细胞线粒体呼吸的节律，在活动期开始时最大解偶联 取决于正常工作的时钟。此外，13C-葡萄糖进入三羧酸(TCA)循环也是 活动期开始时最高，表明自主昼夜节律控制水分代谢通量 跨越昼夜循环。令人惊讶的是，在BMal1/-脂肪细胞中，我们观察到脂肪细胞的重新编程 代谢伴随琥珀酸中13C标记的增加和其他TCA中间体水平的降低，这是一个特征 压力和ROS的积累。在这里，我们试图测试生物钟控制的假设 燃料通过一个过程进入TCA循环时内脏脂肪组织内的能量通量 被HFD扰乱了。在目标1中，我们将检验摄食时间和脂肪昼夜节律协调的假设 利用遗传谱系示踪动物和新陈代谢的能量利用周期促进健康的脂肪扩张 表型鉴定。我们将评估脂肪组织重塑和进入TCA循环的13C葡萄糖流量 随机或限时喂食常规食物或高脂饲料的小鼠在明暗周期中的脂类和有机酸 在温度中和温度(30oC)时，到光照(错误的喂食时间)或黑暗(最佳喂食时间)。我们还将测试 HFD对Wat时钟的要求及脂肪特异性BMAL1过表达对脂肪的影响 重塑、炎症、纤维化和血糖稳态。目标1的结果将建立相互作用 在能量流动、代谢健康和健康能力方面，Wat时钟和喂养时间之间的关系 脂肪膨胀，特别是新增加的光摄食组与黑暗摄食组相比- 仅限和AL队列。在目标2中，我们将测试HFD废除昼夜节律能量循环的假设 内脏脂肪组织，并诱导表观遗传重塑，走向促炎细胞的命运。我们将表演 在脂肪细胞中串联染色质和表达谱以确定时间特征和分子驱动因素 高脂饲料喂养的即兴及只喂光和暗小鼠的内脏水重构。最后，我们将检查是否 在HFD期间BMal1的过度表达保护了正常喂养的小鼠的健康染色质景观。 目标2的结果将确定染色质活动和转录的时钟控制如何有助于 健康的肥胖症。总而言之，这些研究将确定一天中的时间在脂肪生成和营养流动中的作用， 发现新的靶点以对抗肥胖和昼夜节律紊乱引起的免疫代谢并发症。

Project Summary Obesity and diabetes are increased among individuals subjected to shiftwork, reduced sleep, and social jetlag. High fat diet (HFD) misaligns intrinsic circadian cycles with the light/dark cycle and alters oscillations of metabolic genes in visceral adipose tissue, a key site in the control of energy balance, glucose regulation, and inflammatory disorders. Conversely, restricting HFD to the dark period only realigns meal time with circadian rhythms and enhances insulin sensitivity, promoting healthful obesity. How circadian disruption in visceral adipose tissue contributes to obesity pathophysiology remains unknown. In exciting new data, we show strong day/night rhythms in adipocyte mitochondrial respiration with maximal uncoupling at the onset of the active period that is dependent upon a functional clock. Further, 13C-glucose entry into the tricarboxylic acid (TCA) cycle is also highest at the beginning of the active period, indicating autonomous circadian control of WAT metabolic flux across the day/night cycle. Surprisingly, in Bmal1-/- adipocytes, we observe reprogramming of adipocyte metabolism with increased 13C labeling in succinate and reduced levels of other TCA intermediates, a signature of stress and ROS accumulation. Here we seek to test the hypothesis that the circadian clock controls energy flux within visceral adipose tissue at the level of fuel entry into the TCA cycle through a process disrupted by HFD. In Aim 1, we will test the hypothesis that circadian coordination of feeding time and adipose energy utilization cycles promote healthful adipose expansion using genetic lineage tracer animals and metabolic phenotyping. We will assess adipose tissue remodeling and 13C glucose flux into the TCA cycle in addition to lipid and organic acids across the light-dark cycle in mice fed regular chow or HFD either ad lib or time-restricted to the light (misttimed feeding) or dark (optimal time feeding) period at thermoneutrality (30oC). We will also test the requirement of the WAT clock and the effect of adipose-specific BMAL1 overexpression in HFD on adipose remodeling, inflammation, fibrosis, and glucose homeostasis. Aim 1 results will establish the interplay between the WAT clock and feeding time in energy flux, metabolic health, and capacity for healthful adipose expansion, particularly with the new addition of the light-only feeding group for comparison to the dark- only and AL cohorts. In Aim 2, we will test the hypothesis that HFD abrogates circadian energetic cycles in visceral adipose tissue and induces epigenetic remodeling towards a proinflammatory cell fate. We will perform tandem chromatin and expression profiling in adipocytes to identify the time signature and molecular drivers of visceral WAT remodeling in ad lib and light- and dark-only-fed mice on HFD. Finally, we will examine whether BMAL1 overexpression during HFD preserves the healthful chromatin landscape of regular chow fed mice. Results of Aim 2 will determine how clock control of chromatin activity and transcription contributes to healthful obesity. Collectively, these studies will define the role of time-of-day in adipogenesis and nutrient flux, uncovering novel targets to combat the immunometabolic complications of obesity and circadian disruption.