Silencing the uroguanylin-GUCY2C gut-brain axis mediates leptin resistance in obesity

沉默尿鸟苷蛋白-GUCY2C肠脑轴介导肥胖中的瘦素抵抗

• 批准号: 10534726
• 负责人: Joshua R Barton
• 金额: $ 4.89万
• 依托单位: THOMAS JEFFERSON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-01-01 至 2024-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10534726
• 关键词: Acceleration; Adipocytes; Adipose tissue; Adult; Agonist; Animals; Appetite Regulation; Attenuated; Binding; Biochemical; Body Weight decreased; Cell Nucleus; Cell Surface Proteins; Cell membrane; Cell surface; Cells; Cessation of life; Chronic; Circulation; Clinical; Constipation; Cyclic GMP; Data; Desire for food; Disease; Down-Regulation; Exhibits; Expenditure; Fatty acid glycerol esters; Genetic; Goals; Hormone Receptor; Hormone secretion; Hormones; Hyperphagia; Hypothalamic structure; In Vitro; Intestines; Laboratories; Leptin; Leptin resistance; Ligands; Link; Measures; Mediating; Medical; Metabolic; Metabolism; Methods; Morbidity - disease rate; Mus; Neurons; Neurosecretory Systems; Obese Mice; Obesity; Outcome; Overweight; Patients; Peripheral; Phenotype; Population; Receptor Signaling; Reporter; Resistance; Safety; Satiation; Signal Transduction; Small Intestines; Supplementation; Surface; Syndrome; Therapeutic; Tissues; Transgenes; Transgenic Organisms; Translating; Weight Gain; appetite loss; desensitization; diet-induced obesity; enterotoxin receptor; feeding; gut-brain axis; ineffective therapies; insight; leptin receptor; mortality; mouse model; novel; novel therapeutics; obesity prevention; obesity treatment; pandemic disease; pharmacologic; receptor; reconstitution; repaired; response; translational potential; trend; uroguanylin

PROJECT SUMMARY/ABSTRACT Obesity is a global pandemic with accelerating trends in morbidity, mortality, and medical expenditures. Treatments have been limited in efficacy or burdened with safety concerns. Leptin is a potent anorexigenic hormone and compelling candidate to treat diet-induced obesity (DIO). However, DIO induces leptin resistance, in part, by downregulating leptin receptors (LepRs) on the surface of hypothalamic neurons, rendering leptin therapy ineffective. Overcoming leptin resistance has emerged as a promising goal for obesity therapy. Recently, we discovered that the guanylyl cyclase C (GUCY2C) receptor is specifically expressed in hypothalamic LepR(+) neurons. Like LepR, hypothalamic GUCY2C induces satiety through binding of its hormone, uroguanylin, produced in intestine. In DIO, uroguanylin expression is lost, silencing hypothalamic GUCY2C. Importantly, reconstitution of GUCY2C signaling restores leptin sensitivity and produces weight loss in DIO mice. These data suggest that loss of intestinal uroguanylin in obesity produces leptin resistance by silencing GUCY2C signaling in hypothalamus, decreasing cell-surface LepR. The ultimate long-term goal of this project is to elucidate mechanisms by which GUCY2C signaling in hypothalamus regulates satiety and resists weight gain, to inform the utility of GUCY2C ligand therapy in the treatment and prevention of obesity. To achieve this goal, three specific aims are proposed. Aim 1, the pathophysiologic aim, will demonstrate that the uroguanylin-GUCY2C axis regulates leptin sensitivity. Leveraging unique tissue-specific conditional mouse models developed by our laboratory, we will measure leptin sensitivity of mice before and after eliminating the uroguanylin-GUCY2C signaling axis. Leptin sensitivity in mice with altered GUCY2C signaling will be assessed through phenotypic analysis of satiety and metabolism, and biochemical analysis of LepR signaling. Aim 2, the mechanistic aim, will establish that GUCY2C signaling controls the availability of neuronal surface LepRs. Preliminary data suggest that LepR signaling is reduced in GUCY2C-/- mice. We will use LepR(+) neurons enriched from LepR reporter mice to quantify the effect of GUCY2C signaling on LepR translocation to the cell surface and signaling. Finally, Aim 3, the therapeutic aim, will define the ability of GUCY2C ligands to overcome leptin resistance in DIO mice. Here, we will use clinically available GUCY2C ligands, and mice with a conditional uroguanylin transgene, to reconstitute hypothalamic GUCY2C signaling in DIO mice. Using methods described in Aim 1, we will explore the effects of exogenous or transgenic GUCY2C ligand supplementation on hypothalamic leptin signaling in DIO animals. These studies will reveal new mechanisms contributing to obesity, and novel solutions to overcome canonical leptin resistance and alleviate dysregulation of appetite and satiety in obesity. The potential to translate these results into patients is underscored by approval of GUCY2C ligands to treat chronic constipation syndromes, offering the exciting opportunity of using these ligands to treat obesity.

项目概要/摘要 肥胖是一种全球性流行病，发病率、死亡率和医疗支出呈加速趋势。 治疗效果有限或存在安全问题。瘦素是一种有效的厌食剂 激素是治疗饮食引起的肥胖症（DIO）的有力候选者。然而，DIO 会诱导瘦素抵抗， 部分是通过下调下丘脑神经元表面的瘦素受体（LepR），使瘦素 治疗无效。克服瘦素抵抗已成为肥胖治疗的一个有希望的目标。最近， 我们发现鸟苷酸环化酶 C (GUCY2C) 受体在下丘脑 LepR(+) 中特异性表达 神经元。与 LepR 一样，下丘脑 GUCY2C 通过与其激素尿鸟苷素结合来诱导饱腹感， 肠道内产生。在 DIO 中，尿鸟苷蛋白表达缺失，下丘脑 GUCY2C 沉默。重要的是， GUCY2C 信号的重建可恢复 DIO 小鼠瘦素敏感性并导致体重减轻。这些数据 表明肥胖中肠道尿鸟苷蛋白的缺失会通过沉默 GUCY2C 信号产生瘦素抵抗 在下丘脑中，减少细胞表面 LepR。该项目的最终长期目标是阐明 下丘脑中的 GUCY2C 信号传导调节饱腹感和抵抗体重增加的机制，以告知 GUCY2C配体疗法在治疗和预防肥胖中的效用。为了实现这一目标，三 提出了具体目标。目标 1，即病理生理学目标，将证明尿鸟苷蛋白-GUCY2C 轴调节瘦素敏感性。利用独特的组织特异性条件小鼠模型开发 我们的实验室，我们将测量消除尿鸟苷蛋白-GUCY2C前后小鼠的瘦素敏感性 信号轴。 GUCY2C 信号改变的小鼠的瘦素敏感性将通过表型进行评估 饱腹感和代谢分析，以及 LepR 信号传导的生化分析。目标 2，机械目标，将 确定 GUCY2C 信号传导控制神经元表面 LepR 的可用性。初步数据 表明 GUCY2C-/- 小鼠中 LepR 信号传导减弱。我们将使用从 LepR 中丰富的 LepR(+) 神经元 报告小鼠来量化 GUCY2C 信号传导对 LepR 易位到细胞表面和信号传导的影响。 最后，目标 3（治疗目标）将定义 GUCY2C 配体克服瘦素抵抗的能力 在 DIO 小鼠中。在这里，我们将使用临床上可用的 GUCY2C 配体，以及具有条件性尿鸟苷蛋白的小鼠 转基因，在 DIO 小鼠中重建下丘脑 GUCY2C 信号传导。使用目标 1 中描述的方法，我们 将探讨外源或转基因 GUCY2C 配体补充对下丘脑瘦素的影响 DIO 动物中的信号传导。这些研究将揭示导致肥胖的新机制和新的解决方案 克服典型的瘦素抵抗并减轻肥胖引起的食欲和饱腹感失调。这 GUCY2C 配体获批用于治疗慢性病，强调了将这些结果转化为患者的潜力 便秘综合征，为使用这些配体治疗肥胖提供了令人兴奋的机会。