Embryonic regulation of GnRH neuron migration and function

GnRH 神经元迁移和功能的胚胎调节

• 批准号: 7571644
• 负责人: DAVID J KOZLOWSKI
• 金额: $ 26.84万
• 依托单位: AUGUSTA UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-03-01 至 2013-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7571644
• 关键词: Action Potentials; Address; Adult; Anosmia; Arts; Behavior; Biological Models; Biological Neural Networks; Birth; Brain; Candidate Disease Gene; Cells; Characteristics; Clinical; Clinical Research; Complement; Congenital Abnormality; Cues; Destinations; Development; Developmental Biology; Disease; Electrophysiology (science); Embryo; Embryonic Development; Etiology; Fertility; Fishes; Genes; Genetic; Goals; Gonadotropin Hormone Releasing Hormone; Gonadotropins; Green Fluorescent Proteins; Human; Hypothalamic structure; Immigration; In Vitro; Kallmann Syndrome; Lesion; Location; Mammals; Mediating; Microscopy; Modeling; Molecular; Molecular Genetics; Monitor; Nerve; Neuraxis; Neurobiology; Neuroendocrine Cell; Neurons; Outcome; Patients; Pattern; Peptides; Population; Potassium Channel; Preoptic Areas; Prosencephalon; Regulation; Reproduction; Route; Signal Transduction; Smell Perception; Specific qualifier value; Stereotyping; System; Telencephalon; Testing; Transgenes; Transgenic Organisms; Zebrafish; cell motility; experimental analysis; extracellular; gene function; genetic manipulation; hypothalamic pituitary axis; in vivo; in vivo Model; innovation; mRNA Expression; migration; mutant; neurophysiology; olfactory bulb; overexpression; public health relevance; relating to nervous system; reproductive; research study; teleost fish

DESCRIPTION (provided by applicant): Central nervous system (CNS) control of reproduction is mediated by a population of neuroendocrine cells that secrete gonadotropin-releasing hormone (GnRH). These GnRH neurons originate outside the CNS and migrate into the ventral telencephalon and hypothalamus during embryogenesis. Incorrect migration of GnRH neurons underlies some forms of reproductive disease, namely Kallmann Syndrome. However, the embryonic mechanisms regulating GnRH neuron migration and function are poorly understood. In part, this is because GnRH neurons are few in number and inaccessible in most vertebrate embryos or the intact adult brain. To overcome these barriers, we exploit several experimental features of zebrafish to identify GnRH neurons during embryonic migration and monitor electrophysiological activity in an intact neural network. The goal of this proposal is to elucidate the in vivo mechanisms of GnRH neuron migration and function. In transgenic zebrafish embryos, GnRH neurons express green fluorescent protein soon after birth and increase the rate of spontaneous action potential firing during embryonic migration. We hypothesize that increased electrical activity in GnRH neurons is an in vivo mechanism to regulate migratory rate, route, or destination. We will: 1) Determine when and where migratory GnRH neurons acquire neurophysiological activity, 2) Determine whether stereotyped migration is required for normal GnRH neurophysiology, and 3) Determine whether neuronal activity regulates embryonic migration of GnRH neurons. Experiments outlined in this proposal combine transgenic zebrafish, state-of-the-art microscopy, and single cell electrophysiology to monitor GnRH neuron migration and function in vivo. To determine the functional relationship between GnRH neuron migration and neuronal activity, we will disrupt GnRH neuron migration by manipulating mRNA expression of specific Kallmann genes. Conversely, we will use a GnRH neuron-specific transgene to overexpress a human inward rectifying potassium channel only in GnRH neurons and silence electrical activity during migration. Together, these analyses test the functional relationship between GnRH neuron migration and developmentally acquired electrical activity. Moreover, this system permits cell autonomous tests of human gene function (wild-type or mutant) using an in vivo model of GnRH neuron migration. We have developed a powerful model system and propose an innovative experimental approach to advance our understanding of GnRH neuron migration in vivo. A further understanding of the mechanisms guiding GnRH neuron migration is essential to determine the etiology of birth defects and predict clinical outcomes regarding reproductive maturation and fertility. These results in zebrafish complement ongoing clinical research efforts aimed toward identifying the function of (candidate) genes that underlie the molecular etiology of abnormal GnRH neuron migration in human reproductive disease. Public Health Relevance Statement: Several forms of human reproductive disease are caused by the inappropriate migration or function of specialized neuroendocrine cells that secrete gonadotropin-releasing hormone (GnRH). The goal of this proposal is to identify the molecular mechanisms and neurophysiology of embryonic GnRH neuron migration by exploiting the experimental features of transgenic zebrafish. A further understanding of the mechanisms guiding GnRH neuron migration is essential to determine the etiology of birth defects and predict clinical outcomes regarding reproductive maturation and fertility in humans.

描述（由申请人提供）：中枢神经系统（CNS）控制繁殖是由分泌促性腺激素释放激素（GNRH）的神经内分泌细胞种群介导的。这些GNRH神经元起源于中枢神经系统，并在胚胎发生过程中迁移到腹侧脑脑和下丘脑中。 GNRH神经元的不正确迁移是某些形式的生殖疾病，即Kallmann综合征。然而，对调节GNRH神经元迁移和功能的胚胎机制知之甚少。在某种程度上，这是因为GNRH神经元数量很少，并且在大多数脊椎动物胚胎或完整的成年大脑中无法访问。为了克服这些障碍，我们利用斑马鱼的几个实验特征来鉴定胚胎迁移期间的GNRH神经元，并在完整的神经网络中监测电生理活性。该建议的目的是阐明GnRH神经元迁移和功能的体内机制。 在转基因斑马鱼胚胎中，GNRH神经元在出生后不久表达绿色荧光蛋白，并增加了胚胎迁移期间自发作用的电势触发速率。我们假设GNRH神经元中的电活动增加是调节迁移率，路线或目的地的体内机制。我们将：1）确定迁移GNRH神经元何时何地获得神经生理学活性，2）确定正常GNRH神经生理学是否需要定型的迁移以及3）确定神经元活性是否调节GNRH神经元的胚胎迁移。该提案中概述的实验结合了转基因斑马鱼，最先进的显微镜和单细胞电生理学，以监测GNRH神经元迁移和体内功能。为了确定GNRH神经元迁移与神经元活性之间的功能关系，我们将通过操纵特定Kallmann基因的mRNA表达来破坏GNRH神经元迁移。相反，我们将使用GNRH神经元特异性转基因在GNRH神经元中仅在GNRH神经元中过度表达人的向内整流钾通道，并在迁移过程中使用沉默的电活动。这些分析共同测试了GnRH神经元迁移与发育获得的电活动之间的功能关系。此外，该系统允许使用GNRH神经元迁移的体内模型对人类基因功能（野生型或突变体）进行细胞自主测试。我们已经开发了一个强大的模型系统，并提出了一种创新的实验方法，以促进我们对体内GNRH神经元迁移的理解。对指导GNRH神经元迁移的机制的进一步理解对于确定先天缺陷的病因和预测有关生殖成熟和生育能力的临床结果至关重要。这些结果是斑马鱼补充正在进行的临床研究工作，旨在确定（候选）基因的功能，这些基因是人类生殖疾病中异常GnRH神经元迁移的分子病因。 公共卫生相关性陈述：几种形式的人类生殖疾病是由分泌促性腺激素释放激素（GNRH）的专门神经内分泌细胞的不当迁移或功能引起的。该建议的目的是通过利用转基因斑马鱼的实验特征来确定胚胎GNRH神经元迁移的分子机制和神经生理学。对指导GNRH神经元迁移的机制的进一步理解对于确定先天缺陷的病因和预测人类生殖成熟和生育能力的临床结果至关重要。