Exploration of the role of CART/GPR160 in metabolism in the setting of Magel2 deficiency: Implications for Prader Willi Syndrome

探索 Magel2 缺陷情况下 CART/GPR160 在代谢中的作用：对普瑞德威利综合征的影响

• 批准号: 10353236
• 负责人: Gina L.C. Yosten
• 金额: $ 22.73万
• 依托单位: SAINT LOUIS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-06-10 至 2024-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10353236
• 关键词: Ablation; Address; Affect; Agonist; Amphetamines; Animal Model; Appetite Regulation; Behavior; Biology; Body Weight; Brain; CARTPT gene; Chemicals; Chromosome 15; Chromosome Arm; Clinical; Cocaine; Data; Desire for food; Disease; Eating; Ensure; Enzymes; Exhibits; Fasting; Foundations; G-Protein-Coupled Receptors; Genes; Goals; High Fat Diet; Human; Hunger; Hyperphagia; Hypothalamic structure; Immunohistochemistry; Individual; Infusion procedures; Inherited; Injections; Knowledge; Lead; Life; Link; Locomotion; Lysosomes; Maternal uniparental disomy; Measures; Messenger RNA; Metabolic; Metabolic dysfunction; Metabolism; Methods; Modeling; Monitor; Morbid Obesity; Motor Activity; Mus; Mutation; Neuropeptides; Obesity; Orphan; Pathologic; Patients; Pattern; Peptides; Physiological; Plasma; Prader-Willi Syndrome; Predisposition; Process; Production; Prohormone Convertase; Proprotein Convertase 1; Proteomics; Rattus; Reporting; Research; Rodent; Rodent Model; Role; Satiation; Secretory Vesicles; Signal Transduction; Single Nucleotide Polymorphism; System; Technology; Therapeutic; Thinness; Tissues; Water consumption; Weight; Weight Gain; base; behavior test; design; early-onset obesity; experience; feeding; imprint; innovation; knock-down; male; neuronal circuitry; neuroregulation; new therapeutic target; prohormone; protein degradation; protein expression; protein transport; rare genetic disorder; receptor; reduced food intake; response; small hairpin RNA; therapeutic target; treatment strategy; ubiquitin-protein ligase

PROJECT SUMMARY Severe hyperphagia is a hallmark of Prader Willi Syndrome (PWS). Multiple neuronal circuits have been implicated in PWS-associated hyperphagia; however the complexity of the neural regulation of appetite has obfuscated the precise mechanisms underlying the dysregulation of feeding circuits in the setting of PWS. The neuropeptide cocaine and amphetamine regulated transcript (CART) is a key regulator of appetite and weight. Central infusion of CART decreased food intake and weight gain in obese rats, and global deletion of CART in mice led to predisposition to obesity and enhanced susceptibility to high fat diet-induced metabolic dysfunction. Likewise, mutations in the CART gene have been linked to obesity in humans. Interestingly, hypothalamic levels of CART peptide were reduced in an animal model of PWS. In spite of a wealth of evidence indicating an important role of CART in metabolism, the ability of CART to reduce food intake in models of PWS has not been reported. This lack of knowledge represents a major gap in the PWS field. Importantly, we recently identified the cognate receptor of CART as the G protein coupled receptor, GPR160, thus enabling chemical biology methods to design CART agonists for the treatment of PWS-associated hyperphagia. We hypothesize that central injection of CART will reduce food intake in the setting of paternally-inherited Magel2 deficiency, and that Magel2 deficiency will lead to reduced expression of CART in central feeding centers, particularly the hypothalamus. We will address our hypothesis in two Specific Aims. In Aim 1, we will inject CART icv into Magel2-deficient rats, and food and water intakes and meal patterning will be measured using our BioDAQ system. Rats will then be placed in an open field behavioral test to ensure that any observed effect of CART on food intake is due to a primary effect of CART on appetite, rather than a secondary effect on locomotor behavior. Although proCART mRNA levels likely are not modulated in PWS, the prohormone convertase responsible for the production of mature CART, PSCK1, has been shown to be reduced in individuals with PWS, which leads to reductions in the production of mature CART peptide. In Aim 2, we therefore will measure CART, GPR160, and PSCK1 levels in brains, CSF, and plasma of Magel2-deficient rats compared to WT rats. Because CART peptide levels fluctuate with metabolic state (i.e. reduced during fasting, normalized after re-feeding), we will determine if functional changes in CART peptide levels occur in the setting of Magel2 deficiency using global proteomic analyses. Lastly, we will determine if there are changes in the expression patterns of CART and GPR160 in the brains of Magel2-deficient rats compared to WT rats. If our hypotheses are correct, then replacement with CART agonists should at least partially control appetite in individuals with PWS. This strategy of targeting a system that is parallel to, and not dependent upon, other feeding circuits could revolutionize treatment of PWS-associated hyperphagia and offer an innovative solution to the severe obesity experienced by patients with PWS.

项目摘要 严重的女性晶状体是Prader Willi综合征（PWS）的标志。多个神经元电路已经 与PWS相关的脾气暴躁；但是，食欲神经调节的复杂性具有 混淆了PWS环境中进食电路失调的基础机制。这 神经肽可卡因和苯丙胺调节的转录本（CART）是食欲和体重的关键调节剂。 肥胖大鼠的食物摄入量减少和体重增加，全球删除购物车的中心输注，在 小鼠导致肥胖症的易感性，并增强了对高脂肪饮食诱导的代谢功能障碍的敏感性。 同样，手推车基因中的突变也与人类的肥胖有关。有趣的是，下丘脑水平 在PWS的动物模型中减少了CART肽的肽。尽管有大量证据表明 购物车在新陈代谢中的重要作用，马车在PWS模型中减少食物摄入的能力尚未 报告。缺乏知识代表了PWS领域的主要差距。重要的是，我们最近确定了 CART的同源受体作为G蛋白耦合受体GPR160，从而实现化学生物学方法 设计CART激动剂，以治疗与PWS相关的脾气。我们假设这个中心 注射购物车将减少食物的摄入量，在亲属关系的Magel2缺乏症和Magel2的情况下 缺乏将导致中央进食中心，特别是下丘脑的CART表达降低。我们 将以两个具体目标解决我们的假设。在AIM 1中，我们将把Cart ICV注入MAGEL2缺陷大鼠，然后将其注入 食物和水的摄入量和进餐模式将使用我们的Biodaq系统测量。然后将老鼠放置 在开放野外行为测试中，以确保卡车对食物摄入的任何影响都是由于主要的 购物车对食欲的影响，而不是对运动行为的次要影响。虽然procart mRNA 在PWS中可能不调制水平，而荷尔酮转化酶负责成熟的生产 CART，PSCK1已被证明在PWS的个体中减少了，这导致降低 成熟的购物车肽的产生。因此，在AIM 2中，我们将在AIM 2中测量购物车，GPR160和PSCK1水平 与WT大鼠相比，MAGEL2缺陷大鼠的大脑，CSF和血浆。因为购物车肽水平波动 具有代谢状态（即在禁食期间减少，重新喂养后标准化），我们将确定功能是否功能 使用全局蛋白质组学分析，在Magel2缺乏症的情况下发生CART肽水平的变化。 最后，我们将确定CART和GPR160的表达模式是否有变化 与WT大鼠相比，MAGEL2缺乏大鼠。如果我们的假设是正确的，则用卡车激动剂替换 PWS的个体至少应部分控制食欲。针对系统的这种策略是 与其他喂养电路平行，并且不依赖其他喂养电路可能会彻底改变与PWS相关的处理 脾气暴躁，为PWS患者经历的严重肥胖提供了创新的解决方案。