Molecular roles in active and passive mechanics in cochlear hair bundles

耳蜗毛束主动和被动力学中的分子作用

• 批准号: 9127233
• 负责人: Anthony Wei Peng
• 金额: $ 24.9万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2018-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9127233
• 关键词: ATP phosphohydrolase; Acoustic Trauma; Auditory; Auditory system; Brain; Calcium Signaling; Calcium ion; Cell physiology; Cells; Cochlea; DNA Sequence Alteration; Data; Devices; Disease; Drug usage; Ear; Exhibits; External auditory canal; Failure; Frequencies; Future; Generations; Genetic; Goals; Hair; Hair Cells; Health; Hearing; Hearing Impaired Persons; Human Genetics; Inorganic Sulfates; Investigation; Kinetics; Labyrinth; Lead; Link; MYO7A gene; Measures; Mechanics; Mechanoreceptors; Modeling; Molecular; Molecular Models; Molecular Motors; Motor; Motor Activity; Mus; Mutation; Myosin ATPase; Noise-Induced Hearing Loss; Organelles; Outer Hair Cells; Pharmaceutical Preparations; Process; Property; Regulation; Research; Role; Sensory Hair; Signal Transduction; Site; Speed; Stereocilium; Stress; Structure; Synaptic Transmission; System; Technology; Travel; United States; Unspecified or Sulfate Ion Sulfates; Vanadates; Vertebrates; base; cell type; deafness; density; hearing impairment; inhibitor/antagonist; insight; middle ear; molecular modeling; mouse model; novel; pressure; research study; response; sound; vibration; voltage clamp

DESCRIPTION (provided by applicant): Sound vibrations enter the outer ear through the ear canal and are converted into pressure waves by the middle ear. Pressure waves in the inner ear are converted to an electrical signal via the mechano-electrical transduction (MET) process in the hair bundle of sensory hair cells; this electrical signal drives synaptic transmission resultin in information traveling to the brain. Failures in this process lead to hearing loss and deafness. Multiple human genetic mutations exhibit deficits in the MET process. Understanding the basic properties of MET will lead to a better understanding of genetic deafness, leading to targeted treatments and therapies. A growing body of data on mammalian cochlear hair cell MET properties is incompatible with existing molecular models of MET. Specifically, adaptation, a key process of MET universally accepted to be signaled by calcium, does not appear to be driven by calcium ion entry, thus challenging current models of adaptation. To better understand the underlying mechanisms responsible for cochlear MET, mechanical changes in the hair bundle need to be measured at rates that match the fast rates of MET processes in cochlear hair cells. In this proposal, to overcome current technological limitations, new micro-electro-mechanical systems (MEMS) devices are developed to specifically measure cochlear hair bundle mechanics. Using whole-cell voltage clamp recordings of mammalian cochlear hair cells along with new MEMS devices, kinetics and mechanics of fast cochlear MET processes will be measured. This data will be used to generate new models of cochlear MET. Myosin motors localized to the upper tip-link region have been proposed to be important to MET. New experiments in the cochlea will be performed using these novel MEMS devices to characterize mechanics of the hair bundle when modifying motor activity. From these experiments, the role of molecular motors as well as the upper tip-link region in cochlear hair cells in MET processes will be determined. During acoustic trauma, hair bundles are stressed from overstimulation resulting in stiffness changes to the hair bundle. To characterize mechanical properties of the mammalian hair bundle, this proposal aims to quantify the contribution of stereocilia links and the stereocila rootlet to passive hair bundle stiffness using drug application and genetic mouse models lacking specific structures. The experiments in this proposal will further our understanding of the molecular mechanisms of mammalian cochlear MET. Understanding the crucial components in passive hair bundle stiffness will lay groundwork for understanding the key regulation points of hair bundle properties and the effects of acoustic trauma on stereocilia. The technology developed will greatly enhance auditory research and likely have broader mechanics applications in the auditory field and beyond.

描述（由申请人提供）：声音振动通过耳道进入外耳，并通过中耳转化为压力波。内耳中的压力波通过感觉毛细胞的发束中的机械电气转导（MET）过程转换为电信号。该电信号驱动突触传播导致信息传播到大脑。此过程中的失败导致听力丧失和耳聋。多个人类遗传突变在MET过程中表现出缺陷。了解MET的基本特性将使人们更好地了解遗传性耳聋，从而导致靶向疗法和疗法。越来越多的关于哺乳动物耳蜗的数据与现有的MET分子模型不相容。具体而言，适应性是普遍接受的MET的关键过程，该过程似乎不是由钙离子进入的驱动，从而挑战了当前的适应模型。为了更好地理解负责人耳蜗的基本机制，需要以与耳蜗毛细胞中MET过程的快速速率相匹配的发束机械变化。在此提案中，为了克服当前的技术局限性，开发了新的微电动机械系统（MEMS）设备，以专门测量耳蜗头发束机械师。将测量使用哺乳动物耳蜗细胞的全细胞电压夹记录以及新的MEMS设备，快速耳蜗MET过程的动力学和力学。这些数据将用于生成新的人工耳蜗模型。已经提议肌球蛋白电动机位于上尖端链路区域很重要。耳蜗中的新实验将使用这些新型MEMS设备进行，以表征在修改运动活动时发束的力学。从这些实验中，将确定分子电动机以及在MET过程中耳蜗细胞中的上尖端连接区域的作用。在声学创伤期间，过度刺激导致头发束压力，从而导致头发束变化。为了表征哺乳动物头发束的机械性能，该提案旨在使用药物应用和缺乏特定结构的遗传小鼠模型来量化立体核心链接的贡献和立体胶根对被动头发束刚度的贡献。该提案中的实验将进一步了解我们对哺乳动物人工耳蜗的分子机制的理解。了解被动头发束刚度的关键成分将为理解头发束特性的关键调节点以及声学创伤对立体尾膜的影响。开发的技术将大大增强听觉研究，并可能在听觉领域及其他地区具有更广泛的力学应用。