The Intracellular Dynamics of AGRP Neurons under Different Metabolic Conditions

不同代谢条件下 AGRP 神经元的细胞内动力学

基本信息

批准号：
9769009
负责人：
Marcelo Dietrich
金额：
$ 37.46万
依托单位：
YALE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-09-01 至 2020-08-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): The maintenance of energy metabolism is a fundamental homeostatic function found in all organisms from humans to simple cells. Disruption of energy metabolism can lead to life-threatening conditions, including chronic metabolic disorders such as obesity and diabetes. Understanding the regulatory principles that control energy metabolism is of the utmost importance in helping to design better treatments for metabolic disorders. AGRP neurons in the hypothalamus participate in the regulation of energy metabolism and are activated during times of food deprivation. Paradoxically, we showed that AGRP neuronal activity is also elevated in diet- induced obese mice. We have recently found that mitochondria in AGRP neurons undergo fusion when mice switch from negative to positive energy balance (i.e., from food deprived to high-fat fed). When we blocked mitochondria fusion in AGRP neurons (by knocking down Mfn2) in mice fed a high-fat diet, AGRP neuron activity decreased due to reduced intracellular levels of ATP, and the mice became resistant to diet-induced obesity. Because in both food deprived and high-fat diet fed mice the activity of AGRP neurons is high, we hypothesize that AGRP neuron activity is supported by different mechanisms in these two conditions. This is illustrated by the fission state of mitochondria in AGRP neurons during food deprivation, and the fused state in high-fat fed mice. The goal of this application is to provide mechanistic insight into the complexity of the biology involved in the adaptations of AGRP neurons to different metabolic conditions. In Aim 1, we will use cell-specific ribosome profiling of AGRP neurons combined with RNA-sequencing to identify changes in the translational landscape of AGRP neurons. In Sub-Aim 1.1 we will characterize the ribosome-associated transcriptome (translatome) involved in AGRP neuron function in food deprived, fed and high-fat diet fed mice. In Sub-Aim 1.2 we will characterize how the translatome of AGRP neurons is modified in the absence of mitochondria fusion during diet-induced obesity in AGRP-Mfn2KO mice. These experiments will identify the putative intracellular mechanisms that allow AGRP neurons to adapt to the changing metabolic milieu. In Aim 2, we will tackle a very important mechanistic question that is whether mitochondrial dynamics in AGRP neurons is controlled by the electrical activity of the cells. We will use a multi-faceted approach to selectively and acutely activate/inhibit Agrp neurons utilizing transgenic and AAV-mediated mouse models with the goal of identifying dynamic morphological changes in mitochondria through electron microscopic analyses. This proposal will deliver novel insights into the central regulation of metabolism and offer new candidates to pursue as drug targets for obesity and related metabolic disorders.

描述（由适用提供）：能量代谢的维持是从人类到简单细胞的所有生物中发现的基本稳态功能。能量代谢的破坏会导致威胁生命的疾病，包括肥胖和糖尿病等慢性代谢疾病。了解控制能量代谢的监管原理在帮助设计更好的代谢疾病治疗方面至关重要。下丘脑参与能量代谢的调节中的AGRP神经元，并在食物剥夺时期被激活。矛盾的是，我们表明饮食诱导的肥胖小鼠中AGRP神经元活性也升高。我们最近发现，当小鼠从阴性到正能量平衡（即，从被剥夺的食物转换为高脂饲料）时，AGRP神经元中的线粒体会融合。当我们阻断AGRP神经元中的线粒体融合（通过击倒MFN2）在喂养高脂饮食的小鼠中，由于细胞内ATP的降低，AGRP神经元活性降低，并且小鼠对饮食诱导的肥胖症具有抗性。因为在喂养小鼠的食物和高脂饮食中，AGRP神经元的活性都很高，所以我们假设在这两种情况下，AGRP神经元的活性受到不同机制的支持。食物剥夺期间AGRP神经元中线粒体的裂变状态以及高脂喂养小鼠的融合状态来说明这一点。该应用的目的是提供机械洞察力，了解与AGRP神经元适应不同代谢条件的生物学的复杂性。在AIM 1中，我们将使用AGRP神经元的细胞特异性核糖体分析与RNA测序结合，以识别AGRP神经元转化景观的变化。在Sub-Aim 1.1中，我们将表征与核糖体相关的转录组（Translateme（Translateme），参与AGRP神经元中的饮食，喂养和高脂饮食中喂养小鼠的小鼠。在Sub-Aim 1.2中，我们将表征AGRP-MFN2KO小鼠饮食诱导的肥胖症期间没有线粒体融合的情况，在没有线粒体融合的情况下，如何修饰AGRP神经元的翻译组。这些实验将确定允许AGRP神经元适应不断变化的代谢环境的假定细胞内机制。在AIM 2中，我们将解决一个非常重要的机械问题，即AGRP神经元中的线粒体动力学是否受细胞的电活动控制。我们将使用多方面的方法使用转基因和AAV介导的小鼠模型有选择地，急性激活/抑制AGRP神经元，目的是通过电子显微镜分析鉴定线粒体的动态形态变化。该建议将对代谢中心法规的新颖见解，并为新候选人提供作为肥胖症和相关代谢疾病的药物靶标。