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（由适用提供）：肥胖症折磨了三分之一的美国人，是全球死亡和残疾的主要原因。目前的疗法并不能解决肥胖，因为从根本上放松了能量平衡，并且在很大程度上未能削弱持续的流行病。更好地了解下丘脑对能量平衡的控制应改善治疗。尽管大量工作表明，下丘脑葡萄糖反应性神经元可以刺激或抑制喂养，但对调节能量平衡电路的专用下丘脑神经胶质细胞（称为tanycytes）的了解较少。 tanycytes在腹侧第三脑室壁中排成一壁，并在下丘脑和脑脊液中唯一位置。他们将长时间的过程投射到下丘脑中，与饮食响应性神经元形成广泛的接触，调节甲状腺素神经元的活性，并且是在本应出现后添加到该电路中的新神经元的神经源祖细胞。啮齿动物中的实验增强或减轻丹尼氏症衍生的下丘脑神经发生会影响体重增加。然而，神经源性tanycytes的精确身份尚不清楚，调节tanycyte生发活性的内源性信号传导机制尚不清楚。使用开发的成像技术用于对脑室内侧的细胞进行分析，对小鼠和人类进行了初步研究，揭示了两种偏离的tanycytes-bi-纤维膜的分离亚群，其中有两个长纤毛和一个单一的tanycytes，具有一个短的初级纤毛。有趣的是，发现在胰腺β细胞中表达的葡萄糖传感分子定位于tanycyte oirpar纤毛，这表明这些细胞使用的可能反馈机制可检测能量平衡。初步实验表明，消融tanycyte cilia导致类似糖尿病的表型。 tanycyte子集还显示出不同的分子标记表达，允许构建两个表达CRE的腺病毒，以专门靶向和谱系 - 这两个种群。在AIM 1中，这项研究将采用CRE腺病毒的立体定向3室注射到CRE报告中，以确定神经源性tanycytes的身份。在AIM 2中，同样的注射将用于在有条件的基因敲除小鼠中用floxed kif3a的等位基因烧蚀纤毛，这需要纤毛生成。然后，这些小鼠将接受一系列代谢测试，包括对食物摄入和能量消耗的测量，无论是否有其他代谢挑战，包括饮食诱导的肥胖和糖糖态。拟议的工作将更深入地了解tanycyte子类型，tanycyte衍生的下丘脑神经发生以及tanycyte cilia在葡萄糖感应和能量平衡中的功能。从治疗的角度来看，这些结果可能会促进针对脑室室内疗法的tanycyte cilia的未来药理实验，以调节能量不平衡状态。