Synaptic and Functional Changes in Cochlear and Vestibular Hair Cells of Tmc Mutant Mice

Tmc 突变小鼠耳蜗和前庭毛细胞的突触和功能变化

• 批准号: 10186451
• 负责人: John Lee
• 金额: $ 7.06万
• 依托单位: HARVARD MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-01 至 2021-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10186451
• 关键词: Address; Alleles; Animal Model; Auditory; Automobile Driving; Behavior; Calcium; Cell Survival; Cell physiology; Child; Childhood; Cochlea; Cues; DNA Sequence Alteration; Data; Dependovirus; Development; Discrimination; Epithelial; Epithelium; Equilibrium; Evoked Potentials; Exhibits; Fiber; Functional disorder; Genes; Genetic; Glutamates; Goals; Gold; Hair; Hair Cells; Harvest; Head; Hearing; Human; Impairment; Injections; Inner Hair Cells; Knockout Mice; MYO7A gene; Maintenance; Measurable; Measures; Mediating; Membrane; Morphology; Motor; Mus; Mutant Strains Mice; Mutation; Natural regeneration; Organ; Peripheral; Permeability; Phenotype; Population; Proteins; Pure-Tone Audiometry; Recovery; Recovery of Function; Research Proposals; Saccule and Utricle; Saccule structure; Safety; Sensory; Supine Position; Synapses; Synaptic Transmission; Testing; Time; Tinnitus; Utricle structure; Vesicle; Vestibular Hair Cells; Viral Genes; Viral Vector; Wild Type Mouse; World Health Organization; calbindin; calretinin; deafness; design; experimental study; gene therapy; genetic deafness; hearing impairment; hearing restoration; improved; in vivo; insight; mechanotransduction; nerve supply; neurofilament protein H; novel; partial recovery; restoration; ribbon synapse; round window; speech in noise; transmission process

Project Summary/Abstract Transmembrane channel-like proteins 1 and 2 (TMC1 and TMC2) are required for sensory transduction in auditory and vestibular hair cells. Mice with targeted deletion of Tmc1 (Tmc1Δ/Δ) exhibit deafness and those lacking both (Tmc1Δ/ΔTmc2Δ/Δ) display deafness, vestibular dysfunction, and absent sensory transduction. Hair cells exclusively expressing Tmc1 have smaller single-channel conductance and lower calcium permeability than those expressing only Tmc2. While hair bundle morphology, mechanotransduction, and hair cell survival have been assessed in Tmc mutant mice, consequences of absent or impaired sensory transduction on the maintenance of ribbon synapses have not been examined. Cochlear and vestibular hair cells utilize these synapses to mediate synchronous release of glutamate-filled vesicles for temporally precise transmission of auditory cues. Absent or altered numbers of synaptic ribbons can contribute to abnormal synaptic transmission, impaired speech-in-noise discrimination, and perceptual anomalies like tinnitus. This research proposal seeks to characterize the synaptic and functional consequences of impaired/absent sensory transduction in the cochlea and vestibular organs. The focus of Aim 1 is to characterize inner hair cell synapses at various developmental timepoints in Tmc mutant mice and wildtype mice. Preliminary results demonstrate decreased synapse numbers in Tmc1Δ/Δ and Tmc1Δ/ΔTmc2Δ/Δ mice at later time points but not in Tmc2Δ/Δ mice, suggesting the absence of Tmc1 accounts for the observed changes in inner hair cell ribbon synapses. Tmc1 and Tmc2 are not only required for hearing but also necessary for normal vestibular function. Tmc1Δ/ΔTmc2Δ/Δ mice demonstrate abnormal behaviors including head-bobbing, inability to right from supine positions, and circling. While behavior has been characterized in Tmc mutant mice, the status of the vestibular periphery has not been examined in detail. The focus of Aim 2 is to analyze vestibular hair cell synapses in utricles and saccules of Tmc mutant mice and to directly assess vestibular function using vestibular sensory evoked potentials (VsEPs). Studies in recent years have verified the safety and efficacy of viral vectors for delivery into mouse cochlea and utilized these viral gene therapies to restore auditory function in mice lacking Tmc1. However, recovery of vestibular function and synapses via gene therapy has not yet been examined. The focus of Aim 3 is to assess synaptic and functional recovery in Tmc mutant mice following gene therapy by comparing data acquired after injections to those collected from Aims 1 and 2. Data generated from this proposal will provide novel insight into the mechanisms underlying ribbon synapse maintenance, enhance our understanding of the vestibular periphery, and inform continued development of gene therapies for restoration of hearing and balance.

项目摘要/摘要 跨膜通道样蛋白1和2（TMC1和TMC2）在感觉翻译中需要 听觉和前庭毛细胞。具有TMC1（TMC1Δ/δ）靶向缺失的小鼠暴露死亡度， 缺少（TMC1Δ/ΔTMC2Δ/δ）表现出死亡度，前庭功能障碍和不存在的感觉传递。头发 专门表达TMC1的细胞具有较小的单通道电导和较低的钙渗透性 比仅表达TMC2的人。而头发束形态，机械转导和毛细胞存活 已经在TMC突变小鼠中进行了评估，没有感觉转移的后果 尚未检查色带突触的维护。人工耳蜗和前庭毛细胞利用这些 突触中位数同步释放谷氨酸蔬菜，以临时精确传播 听觉提示。突触丝不存在或改变的突触色带可能会导致异常突触 传播，毫无疑问的语音歧视以及耳鸣等感知异常。这项研究 提案旨在表征受损/缺失的SEDRY的突触和功能后果 耳蜗和前庭器官的转导。目标1的重点是表征内毛细胞 TMC突变小鼠和野生型小鼠的各种发育时点的突触。初步结果 证明在TMC1δ/δ和TMC1Δ/δTMC2δ/δ小鼠中的突触数量减少，但不在 TMC2Δ/δ小鼠，这表明没有TMC1是内部毛细胞色带的观察到的变化 突触。 TMC1和TMC2不仅需要听力，而且对于正常的前庭功能也是必需的。 TMC1Δ/ΔTMC2δ/δ小鼠表现出异常行为，包括头脑bling，无法从补充 位置和盘旋。虽然行为在TMC突变小鼠中的表征，但前庭状态 尚未详细检查外围。 AIM 2的重点是分析前庭毛细胞突触 TMC突变小鼠的Ureticles和Saccles，并使用前庭感觉直接评估前庭功能 诱发电位（VSEP）。近年来的研究验证了病毒向量的安全性和效率 输送到小鼠耳蜗中，并利用这些病毒基因疗法来恢复缺乏的小鼠的听觉功能 TMC1。但是，尚未检查通过基因疗法的前庭功能和突触的恢复。 AIM 3的重点是评估基因治疗TMC突变小鼠的突触和功能恢复 将注射后获得的数据与从目标1和2收集的数据进行比较。从此生成的数据 提案将提供有关丝带突触维持的机制的新见解，增强了我们 了解前庭外围，并为恢复基因疗法的持续发展提供信息 听力和平衡。