The role of tanycyte cilia in hypothalamic neurogenesis and glucose sensing

单细胞纤毛在下丘脑神经发生和葡萄糖传感中的作用

• 批准号: 9124686
• 负责人: Zaman Mirzadeh
• 金额: $ 6.64万
• 依托单位: ST. JOSEPH'S HOSPITAL AND MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-05 至 2018-04-04
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9124686
• 关键词: Accounting; Address; Adenoviruses; Affect; American; Apical; Appetite Stimulants; Brain; Calcium Oscillations; Cause of Death; Cell Line; Cells; Cerebral Ventricles; Cerebrospinal Fluid; Characteristics; Cilia; Classification; Diet; Eating; Electron Microscopy; Energy Intake; Energy Metabolism; Environment; Epidemic; Equilibrium; Face; Feedback; Food Energy; Fostering; Future; Glucose; Human; Hypothalamic structure; Imaging Techniques; Injection of therapeutic agent; Intraventricular; Knockout Mice; Label; Lead; Location; LoxP-flanked allele; Maps; Measurement; Metabolic; Mus; Neuroglia; Neurons; Obesity; Output; Pharmaceutical Preparations; Phenotype; Population; Positioning Attribute; Process; Reporter; Research; Rodent; Role; Signal Transduction; Structure of beta Cell of islet; Surface; Testing; Therapeutic; Third ventricle structure; Transgenic Mice; Ventricular; Weight Gain; Work; base; blood glucose regulation; cilium biogenesis; diabetic; disability; energy balance; feeding; improved; insulin sensitivity; mind control; molecular marker; nerve stem cell; neurogenesis; neuronal circuitry; progenitor; public health relevance; research study; targeted treatment; tool

 DESCRIPTION (provided by applicant): Obesity afflicts one in three Americans and is a leading cause of death and disability worldwide. Current therapies do not address obesity as fundamentally deregulated energy balance and have largely failed to curtail the ongoing epidemic. Better understanding of hypothalamic control over energy balance should lead to improved therapy. While extensive work has shown that hypothalamic glucose-responsive neurons can stimulate or suppress feeding, less is known about specialized hypothalamic glial cells called tanycytes that modulate the energy balance circuit. Tanycytes line the ventral third ventricle wall and are uniquely positioned between the hypothalamus and cerebrospinal fluid. They project long processes into the hypothalamus that form extensive contacts with the diet-responsive neurons, modulate the activity of orexigenic neurons, and are neurogenic progenitors for new neurons added to this circuit postnatally. Experimentally enhancing or ablating tanycyte-derived hypothalamic neurogenesis in rodents affects weight gain. However, the precise identity of neurogenic tanycytes is unclear and endogenous signaling mechanisms that regulate tanycyte germinal activity are unknown. Using an imaging technique developed for en-face analysis of cells lining the cerebral ventricles, preliminary studies in mice and humans revealed two segregated subsets of tanycytes-bi-ciliated tanycytes with two long cilia and uni-ciliated tanycytes with a single short primary cilium. Intriguingly, glucose-sensing molecules expressed in pancreatic beta cells were found localized to tanycyte primary cilia, suggesting a possible feedback mechanism used by these cells to detect energy balance. Preliminary experiments showed that ablating tanycyte cilia resulted in a diabetic-like phenotype. Tanycyte subsets also displayed distinct molecular marker expression that permitted construction of two Cre-expressing adenoviruses to specifically target and lineage-trace the two populations. In Aim 1, this study will employ stereotactic 3rd ventricular injections of the Cre adenoviruses into Cre reporter mice to determine the identity of neurogenic tanycytes. In Aim 2, the same injections will be used to ablate cilia in conditional knockout mice with floxed alleles of Kif3a, required fo ciliogenesis. These mice will then be subject to a battery of metabolic tests including measurements of food intake and energy expenditure with or without additional metabolic challenges including diet-induced obesity and glucoprivic states. The proposed work will provide deeper understanding of tanycyte subtypes, tanycyte-derived hypothalamic neurogenesis, and the function of tanycyte cilia in glucose-sensing and energy balance. From a therapeutic perspective, these results may foster future pharmacological experiments targeting tanycyte cilia with intraventricular therapies to modulate states of energy imbalance.

 描述(申请人提供)：肥胖困扰着三分之一的美国人，是世界范围内导致死亡和残疾的主要原因。目前的治疗方法并没有从根本上解决肥胖问题，因为它从根本上解除了能量平衡，而且在很大程度上未能遏制目前的流行病。更好地了解下丘脑对能量平衡的控制应该会导致治疗的改进。虽然广泛的研究表明，下丘脑对葡萄糖反应的神经元可以刺激或抑制进食，但对调节能量平衡回路的特殊下丘脑神经胶质细胞--张力细胞--知之甚少。伸展细胞排列在腹侧第三脑室壁上，位于下丘脑和脑脊液之间。它们将长的突起投射到下丘脑，与饮食反应神经元形成广泛的接触，调节食欲生成神经元的活动，是出生后添加到这个回路中的新神经元的神经源性祖细胞。在实验中增强或消融啮齿动物下丘脑软化细胞来源的神经发生会影响体重增加。然而，神经源性柔韧细胞的确切身份尚不清楚，调节柔韧细胞生发活动的内源性信号机制也尚不清楚。使用一种为脑室衬里细胞进行表面分析而开发的成像技术，在小鼠和人类身上的初步研究揭示了两种分离的柔韧细胞亚群--具有两个长纤毛的双纤毛柔韧细胞和具有单一短初级纤毛的单纤毛柔韧细胞。有趣的是，在胰岛β细胞中表达的葡萄糖感应分子被发现定位于柔韧细胞的初级纤毛，这表明这些细胞可能使用了一种反馈机制来检测能量平衡。初步实验表明，去除柔韧细胞纤毛会导致糖尿病样表型。Tanycell亚群还显示出不同的分子标记表达，这使得构建两个表达Cre的腺病毒能够特异性地针对这两个群体并追踪其谱系。在目标1中，本研究将采用立体定向第三脑室注射Cre腺病毒到Cre报告小鼠体内，以确定神经源性张力细胞的身份。在目标2中，同样的注射将用于消融条件基因敲除小鼠的纤毛，Kif3a是纤毛发生所需的牙线状等位基因。然后，这些小鼠将接受一系列代谢测试，包括测量食物摄入量和能量消耗，以及是否存在额外的代谢挑战，包括饮食诱导的肥胖和葡萄糖代谢状态。这项拟议的工作将提供对柔韧细胞亚型、柔韧细胞衍生的下丘脑神经发生以及柔韧细胞纤毛在葡萄糖感知和能量平衡中的功能的更深入的了解。从治疗的角度来看，这些结果可能会促进未来针对柔韧细胞纤毛的药理学实验，通过脑室内疗法来调节能量失衡的状态。