DEVELOPMENT AND REGULATION OF THE LUTEINIZING HORMONE RELEASING HORMONE SYSTEM

黄体生成素释放激素系统的发育和调控

• 批准号: 6432909
• 负责人: SUSAN WRAY
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF NEUROLOGICAL DISORDERS AND STROKE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6432909
• 关键词: N acetylglucosamine; carbohydrate transport; cell migration; developmental neurobiology; embryo /fetus tissue /cell culture; gamma aminobutyrate; gene expression; genetic promoter element; genetic regulation; genetic transcription; genetically modified animals; glycosylation; gonadotropin releasing factor; histochemistry /cytochemistry; laboratory mouse; messenger RNA; neural cell adhesion molecules; neuronal transport; neurons; neurotransmitters; olfactory lobe; peptide hormone biosynthesis; second messengers; secretion; tunicamycin

LHRH neurons, critical for reproduction, are derived from the nasal placode and migrate into the brain where they become integral members of the hypothalamic-pituitary-gonadal axis. We study mechanism(s) underlying LHRH neuronal differentiation,migration and axonal targeting in normal/transgenic animals, and nasal explants. Intrinsic and trans-synaptic regulation of LHRH gene expression, peptide synthesis and secretion in embryonic LHRH neurons (outside the CNS) versus postnatal LHRH neurons (in the CNS) is studied using nasal explants and organotypic cultures, respectively. Previous work in our lab using nasal explants 1) showed that outgrowth of olfactory axons and migration of LHRH neurons occur in isolated olfactory pit tissue, 2) revealed olfactory axon 'guidance cues' localized to midline nasal cartilagenous tissue and 3) identified two 'developmental genes' in LHRH neurons; AP-2 (a developmental transcription factor) and a novel gene termed NELF. Over the past year, we have addressed the role of AP-2 in LHRH development using normal and AP-2 mutant mice. These studies demonstrate that AP-2 restricts LHRH expression from cells in the respiratory epithelium and is important for maintenance of LHRH gene expression as LHRH cells enter the CNS. Over the past year, we also characterized the expression pattern of NELF during development NELF is primarily limited to PNS and CNS tissues. Pertinent to our work, the encoded protein is expressed in the olfactory system and migrating LHRH neurons. Antisense experiments demonstrated that knock-down of NELF decreased olfactory axon outgrowth and subsequent LHRH neuronal migration. We hypothesize NELF acts via a homophilic interaction. Future studies are directed at understanding the role of NELF during development and the downstream signals activated by this molecule that result in axon outgrowth and cell movement. To understand the regulation of LHRH neurons and their cellular responses, we are examining the activity of LHRH neurons in nasal explants. We have found that there are important maturational events that are intrinsic properties of these cells. We have also demonstrated that LHRH neurons maintained in vitro can release LHRH peptide and rapidly synthesize new peptide in response to a secretory event. Work in progress is focused on: 1) isolation of the midline cues which influence olfactory axon outgrowth; 2) the role of NELF and other molecules in LHRH migration, 3) whether LHRH neurons maintained in nasal explants (devoid of brain influences) show rhythmic activity patterns and if so the mechanisms underlying this rhythm, and 4) genes differentially expressed in LHRH neurons as a function of developmental and reproductive state.

LHRH神经元，生殖的关键，是从鼻基板和迁移到大脑，在那里他们成为下丘脑-垂体-性腺轴的组成部分。我们在正常/转基因动物和鼻外植体中研究LHRH神经元分化、迁移和轴突靶向的潜在机制。利用鼻外植体和器官型培养物分别研究了胚胎LHRH神经元（CNS外）与出生后LHRH神经元（CNS内）LHRH基因表达、肽合成和分泌的内在和跨突触调节。我们实验室先前使用鼻外植体的工作1）表明，嗅觉轴突的生长和LHRH神经元的迁移发生在孤立的嗅窝组织中，2）揭示了定位于中线鼻软骨组织的嗅觉轴突“引导线索”，3）确定了LHRH神经元中的两个“发育基因”; AP-2（一种发育转录因子）和一种称为NELF的新基因。 在过去的一年中，我们已经解决了AP-2在LHRH发展中的作用，使用正常和AP-2突变小鼠。 这些研究表明，AP-2限制呼吸道上皮细胞中LHRH的表达，并在LHRH细胞进入CNS时对维持LHRH基因表达很重要。 在过去的一年中，我们还表征了NELF在发育过程中的表达模式，NELF主要限于PNS和CNS组织。与我们的工作相关，编码的蛋白质在嗅觉系统和迁移的LHRH神经元中表达。 反义实验表明，敲低NELF减少嗅觉轴突生长和随后的LHRH神经元迁移。我们假设NELF的行为通过一个同性恋的相互作用。 未来的研究旨在了解NELF在发育过程中的作用以及由该分子激活的导致轴突生长和细胞运动的下游信号。为了了解LHRH神经元及其细胞反应的调节，我们正在检查鼻外植体中LHRH神经元的活性。 我们已经发现，这些细胞的内在属性是重要的成熟事件。 我们还证明了体外培养的LHRH神经元可以释放LHRH肽并快速合成新的肽以响应分泌事件。目前的工作主要集中在：1）分离影响嗅轴突生长的中线线索; 2）NELF和其他分子在LHRH迁移中的作用; 3）LHRH神经元在鼻组织块中是否维持（没有大脑的影响）显示出有节奏的活动模式，如果是这样，这种节奏的机制，和4）在LHRH神经元中差异表达的基因作为发育和生殖状态的函数。