Trophic Interactions in Developing and Adult Inner Ear

发育中和成人内耳的营养相互作用

基本信息

批准号：
7713536
负责人：
Gabriel Corfas
金额：
$ 45.93万
依托单位：
BOSTON CHILDREN'S HOSPITAL
依托单位国家：
美国
项目类别：
财政年份：
2002
资助国家：
美国
起止时间：
2002-02-15 至 2013-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7713536
关键词：
Ablation Adult Afferent Neurons Affinity Aftercare Age Animals Auditory Axon Back Biological Models Birth Brain-Derived Neurotrophic Factor Cells Cochlea Dependence Diet Dominant-Negative Mutation Down-Regulation Ear Embryonic Development Epithelium Equilibrium ErbB4 gene Functional disorder Genes Genetic Models Genetic Recombination Glial Fibrillary Acidic Protein Glutamate Receptor Grant Hair Cells Health Hearing Image In Situ Hybridization Incidence Inner Hair Cells Knock-out Knockout Mice Labyrinth LacZ Genes Maintenance Modeling Molecular Mus Nerve Nerve Degeneration Nerve Growth Factor Receptors Neuregulin 1 Neuroglia Neurons Neuropathy Neurotrophin 3 Noise Organ Organ of Corti Pathogenesis Pattern Peripheral Pharmaceutical Preparations Phenotype Play Predisposition Prevalence Process Receptor Signaling Relative (related person)Reverse Transcriptase Polymerase Chain Reaction Role Sensorineural Hearing Loss Sensory Sensory Ganglia Signal Pathway Signal Transduction Source Structure Supporting Cell Synapses System Technology Testing Thiamine Time Tissues Transgenic Mice Transgenic Organisms Work base deprivation equilibration disorder ganglion cell genetic manipulation hearing impairment insight morphometry mouse model mutant nerve supply neuron loss neuronal survival neurotrophic factor overexpression postnatal promoter receptor recombinase research study response ribbon synapse spiral ganglion

项目摘要

DESCRIPTION (provided by applicant): The cellular and molecular mechanisms underlying long-term neuronal survival in the inner ear remain poorly understood. Histopathological correlations have suggested that hair cells are a critical source of survival signals for the VIIIth nerve. However, our work indicates that supporting cells in both cochlear and vestibular epithelia play key roles in neuronal maintenance via the neuregulin 1-erbB receptor and neurotrophin-Trk signaling pathways. Postnatal loss of erbB signaling in supporting cells leads to neuronal degeneration, preceded by a specific loss of NT3 in the cochlea and BDNF in the vestibular organs, at a time when these neurotrophins (NTs) are expressed primarily by supporting cells. Since erbB receptor signaling induces NT expression in other non-neuronal cells, and since inner ear sensory neurons express NRG1, we hypothesize that: NRG1, produced by cochlear and vestibular sensory neurons, induces supporting cells to express NTs, NT3 in the organ of Corti and BDNF in the vestibular epithelia. These NTs, acting back on the neurons, maintain their synaptic contacts with hair cells, induce their survival and preserve their function. We will test this hypothesis using genetically modified mice. In Aim 1, inducible cell-specific knockouts will test if elimination of either NT3 or BDNF in supporting cells or hair cells causes neuronal degeneration and inner ear dysfunction; and conditional cell-specific overexpression transgenics will test if the neuronal degeneration caused by loss of erbB signaling in supporting cells can be rescued by increasing NT expression. In Aim 2, we evaluate inner hair cell contributions to long-term neuronal maintenance using mice lacking the high-affinity thiamine transporter such that dietary thiamine restriction leads to widespread and selective loss of inner hair cells, without damage to supporting cells. Inner ear tissues will be quantitatively assessed over time by confocal morphometry of hair cell synapses and sensory ganglion cells, functional tests of evoked responses, and assessment of gene levels/patterns of expression of key trophic factors and their receptors using RT-PCR and in situ hybridization. Comparison of phenotypes obtained when controlling the up- or down-regulation of NT3 vs. BDNF in hair cells vs. supporting cells at different post-natal ages will provide insights into the specific roles of each neurotrophin, the cells involved in the signaling pathways, and the age-dependence of neuronal susceptibility to trophic factor deprivation. These experiments will provide important insights into the pathogenesis and potential treatment of sensorineural hearing loss and peripheral balance disorders. Progressive dysfunction of the inner ear is an important health issue. In spite of the high incidence of hearing and balance disorders, the cellular and molecular mechanisms that contribute to the long-term integrity of inner ear structure and function remain poorly understood. This project will investigate the cellular and molecular mechanisms involved in the long-term survival and function of inner ear sensory neurons using transgenic mouse models.

描述（由申请人提供）：内耳长期神经元存活的基础的细胞和分子机制仍然很少了解。组织病理学相关性表明毛细胞是维特神经的生存信号的关键来源。但是，我们的工作表明，通过神经蛋白1-ERBB受体和神经营养蛋白-TRK信号通路，人工耳蜗和前庭上皮中的支撑细胞在神经元维持中起关键作用。支持细胞中ERBB信号的产后丧失导致神经元变性，此前这些神经营养蛋白（NTS）主要通过支持细胞表示，在前庭器官中的耳蜗和BDNF中的特异性损失。由于ERBB受体信号传导在其他非神经元细胞中诱导NT表达，并且由于内耳感官神经元表达NRG1，因此我们假设是：NRG1，由人工耳蜗和前庭感觉神经元产生，诱导支持细胞以表达NT3的NT3，在Corti和Bdnf int the bdibular Epithia中表达NT3。这些NT在神经元上作用，保持与毛细胞的突触接触，诱导其存活并保留其功能。我们将使用转基因小鼠检验这一假设。在AIM 1中，可诱导的细胞特异性敲除将在支撑细胞或毛细胞中消除NT3或BDNF是否会导致神经元变性和内耳功能障碍；有条件的细胞特异性过表达转基因将测试是否可以通过增加NT表达来挽救ERBB信号传导引起的神经元变性。在AIM 2中，我们使用缺乏高亲和力硫胺素转运蛋白的小鼠评估内毛细胞对长期神经元维持的贡献，从而使饮食中的硫胺素限制会导致内部毛细胞的广泛和选择性损失，而不会损害支持细胞。内耳组织将随着时间的流逝进行定量评估，通过使用RT-PCR和原位杂交评估毛细胞突触和感觉神经节细胞的共焦形态学，诱发反应的功能测试，评估诱发反应的功能测试以及评估关键营养因子及其受体表达的基因水平/模式。在控制毛细胞中NT3与BDNF的上调与不同产后年龄的支持细胞的上调时获得的表型的比较将提供有关每个神经营养素的特定作用，与信号通路相关的细胞的特定作用，以及神经元素对剥夺因素的年龄依赖性。这些实验将提供有关感官听力丧失和外周平衡障碍的发病机理和潜在治疗的重要见解。内耳的渐进功能障碍是一个重要的健康问题。尽管听力和平衡疾病的发生率很高，但有助于内耳结构和功能的长期完整性的细胞和分子机制仍然很熟悉。该项目将使用转基因小鼠模型研究内耳感觉神经元长期生存和功能所涉及的细胞和分子机制。