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）对生殖的控制是由一群分泌促性腺激素释放激素（GnRH）的神经内分泌细胞介导的。这些 GnRH 神经元起源于 CNS 外部，并在胚胎发生过程中迁移到腹侧端脑和下丘脑。 GnRH 神经元的错误迁移是某些形式的生殖疾病（即卡尔曼综合症）的基础。然而，人们对调节 GnRH 神经元迁移和功能的胚胎机制知之甚少。部分原因是 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难以接近。为了克服这些障碍，我们利用斑马鱼的几个实验特征来识别胚胎迁移过程中的 GnRH 神经元，并监测完整神经网络中的电生理活动。该提案的目标是阐明 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就表达绿色荧光蛋白，并增加胚胎迁移过程中自发动作电位放电的速率。我们假设 GnRH 神经元电活动增加是调节迁移速率、路线或目的地的体内机制。我们将：1）确定迁移的 GnRH 神经元何时何地获得神经生理学活动，2）确定正常 GnRH 神经生理学是否需要定型迁移，以及 3）确定神经元活动是否调节 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来监测体内 GnRH 神经元的迁移和功能。为了确定 GnRH 神经元迁移和神经元活动之间的功能关系，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仅在 GnRH 神经元中过度表达人类内向整流钾通道，并在迁移过程中抑制电活动。这些分析共同测试了 GnRH 神经元迁移和发育获得性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（野生型或突变型）进行细胞自主测试。我们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，以增进我们对 GnRH 神经元体内迁移的理解。进一步了解引导 GnRH 神经元迁移的机制对于确定出生缺陷的病因和预测生殖成熟和生育力的临床结果至关重要。斑马鱼的这些结果补充了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学基础。 公共卫生相关性声明：多种形式的人类生殖疾病是由分泌促性腺激素释放激素 (GnRH) 的特殊神经内分泌细胞的不当迁移或功能引起的。该提案的目标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。进一步了解引导 GnRH 神经元迁移的机制对于确定出生缺陷的病因和预测人类生殖成熟和生育力的临床结果至关重要。