ONTOGENY OF THE LUTINIZING HORMONE RELEASING HORMONE SYSTEM

黄化激素释放激素系统的个体发育

• 批准号: 3782410
• 负责人: S 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/3782410
• 关键词: Xenopus; cell cell interaction; cell migration; central neural pathway /tract; developmental neurobiology; embryo /fetus tissue /cell culture; gene expression; genetically modified animals; laboratory mouse; neural cell adhesion molecules; neurofilament proteins; olfactory lobe

LHRH neurons are derived from the olfactory placode and migrate into the brain. The factors dictating cell-specific LHRH gene expression, and the migratory mechanism(s) used by the LHRH neurons during movement into the CNS are currently unknown. We continue to study the prenatal development of the LHRH system both in vivo as well as through the use of in vitro models. We have established that: (1) LHRH neurons are apposed to peripherin positive fibers in nasal and forebrain regions; (2) the olfactory axon/LHRH migratory pathway is N-CAM positive in nasal regions; (3) GABAergic cells are present along this pathway; and (4) olfactory epithelial cells in the olfactory pit express peripherin mRNA. Based on these findings, we hypothesize that peripherin-positive olfactory axons delineate the entire LHRH migratory pathway. We are using embryonic explants, which maintain large numbers of LHRH expressing cells, to test the hypothesis that LHRH neuron migration occurs via interactions with olfactory fibers. Consistent with the in vivo findings, in explants, LHRH neurons are also associated with peripherin-positive fibers, GABAergic cells, and N-CAM-positive pathways. We have shown that LHRH cells in vivo do not posttranslationally modify the cleaved LHRH peptide to the amidated form until reaching the brain. However, in embryonic explants, LHRH cells can produce amidated peptide after 3 days in culture, in the absence of brain tissue. Using transgenic mice containing the LHRH promoter fused to a luciferase reporter, we have targeted luciferase mRNA and product in LHRH neurons. Using a second transgenic line containing the neuron-specific enolase promoter fused to LacZ, neuron-specific enolase positive-nonLHRH cells were detected along the nasal migratory path. In non-mammalian species, two LHRH systems have been described: one located in forebrain (analogous to mammalian LHRH) and the other in midbrain. We cloned a LHRH gene in Xenopus laevis, an organism well-suited for the study of cell-cell interactions. The cDNA showed high homology to mammalian LHRH and encoded a mRNA localized to forebrain cells only. In the frog, LHRH is not expressed until the late larval period, but the location of the LHRH cells indicates that this neuronal population also originates in the olfactory placode, in regions accessible to ablation and transplantation studies. Currently, we are determining: (1) the phenotype(s) of the peripherin-positive cells; (2) the relevance of this peripherin- positive axonal system to the CNS pathway on which LHRH cells migrate; (3) the identity of cells expressing N-CAM and the role of N-CAM in LHRH movement in nasal regions; and (4) whether the GABAergic cells arise from the olfactory placode and share a common lineage wish the LHRH cells during development. Finally, we will use the olfactory placodes of transgenic animals to generate explant cultures and determine if LHRH cells can be identified in situ during migration.

促肾上腺皮质激素释放激素神经元来源于嗅觉平台并迁移 进入大脑。细胞特异性LHRH基因的决定因素 LHRH神经元的表达及迁移机制(S) 在进入中枢神经系统的过程中，目前尚不清楚。我们将继续 LHRH系统在体内的产前发育研究 以及通过使用体外模型。 我们已经证实：(1)LHRH神经元与 鼻区和前脑区的外周蛋白阳性纤维； 鼻内嗅轴突/LHRH迁移通路N-CAM阳性 区域；(3)GABA能细胞沿此途径存在；以及 (4)嗅窝内嗅觉上皮细胞表达 外周蛋白基因。基于这些发现，我们假设 外周蛋白阳性的嗅觉轴突勾画出整个LHRH 迁徙路径。我们使用的是胚胎外植体，它保持了 大量表达LHRH的细胞，以检验这一假设 LHRH神经元通过与嗅觉的相互作用发生迁移 纤维。与体内的发现一致，在外植体中，LHRH 神经元也与外周蛋白阳性纤维有关， GABA能细胞和N-CAM阳性通路。 我们已经证明，体内的LHRH细胞不能翻译后 将切割的LHRH多肽修饰为酰胺化形式，直到 大脑。然而，在胚胎外植体中，LHRH细胞可以产生 培养3天后，在无脑的情况下，胺化多肽 组织。使用融合了LHRH启动子的转基因小鼠 作为一名荧光素酶记者，我们已经锁定了荧光素酶的mRNA和产物 在LHRH神经元中。使用第二个转基因株系，包含 神经元特异性烯醇酶启动子与LacZ融合，神经元特异性 沿鼻腔可检测到烯醇化酶阳性的非LHRH细胞。 迁徙路径。在非哺乳动物物种中，有两个LHRH系统 已被描述：一个位于前脑(类似于哺乳动物) LHRH)，另一个在中脑。我们在非洲爪哇克隆了LHRH基因 Levis，一种非常适合细胞-细胞研究的生物 互动。该基因与哺乳动物LHRH和LHRH有较高同源性 编码一种仅定位于前脑细胞的信使核糖核酸。在青蛙中，LHRH 直到幼虫期晚期才表现出来，而是 LHRH细胞表明，这个神经元群体也 起源于嗅觉定位，在可访问的区域 消融和移植研究。 目前，我们正在确定：(1)表型(S) 外周蛋白阳性细胞；(2)外周蛋白与 LHRH细胞所在的中枢神经系统的阳性轴突系统 迁移；(3)表达N-CAM的细胞的特性及其在其中的作用 N-CAM在鼻区LHRH运动中的作用；以及(4) GABA能细胞起源于嗅觉定位，具有共同的 血统希望LHRH细胞在发育过程中。最后，我们会 利用转基因动物的嗅觉安慰剂产生 组织块培养并确定LHRH细胞是否能在 在迁徙过程中。