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: 9315135
• 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/9315135
• 关键词: ATP phosphohydrolase; Acoustic Trauma; Apical; 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; Hearing; Hearing Impaired Persons; Human Genetics; Investigation; Kinetics; Labyrinth; Lead; Link; MYO7A gene; Measures; Mechanics; Mechanoreceptor Cell; 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; Stress; Structure; Synaptic Transmission; System; Technology; Travel; United States; Unspecified or Sulfate Ion Sulfates; Vanadates; Vertebrates; cell type; deafness; density; experimental study; hearing impairment; inhibitor/antagonist; insight; mechanical properties; mechanotransduction; middle ear; molecular modeling; mouse model; novel; pressure; public health relevance; response; sound; targeted treatment; 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（申请人提供）：声音振动通过耳道进入外耳，并由中耳转换为压力波。内耳中的压力波通过感觉毛细胞毛束中的机电转导 (MET) 过程转换为电信号；这种电信号驱动突触传输，导致信息传输到大脑。这个过程的失败会导致听力损失和耳聋。多种人类基因突变在 MET 过程中表现出缺陷。了解 MET 的基本特性将有助于更好地了解遗传性耳聋，从而制定有针对性的治疗方法。越来越多的关于哺乳动物耳蜗毛细胞 MET 特性的数据与现有的 MET 分子模型不相容。具体来说，适应是普遍认为由钙发出信号的 MET 关键过程，但它似乎不是由钙离子进入驱动的，因此对当前的适应模型提出了挑战。为了更好地了解导致耳蜗 MET 的潜在机制，需要以与耳蜗毛细胞中 MET 过程的快速速率相匹配的速率来测量毛束的机械变化。在该提案中，为了克服当前的技术限制，开发了新的微机电系统（MEMS）设备来专门测量耳蜗毛束力学。使用哺乳动物耳蜗毛细胞的全细胞电压钳记录以及新的 MEMS 设备，将测量快速耳蜗 MET 过程的动力学和力学。该数据将用于生成新的耳蜗 MET 模型。定位于上尖端连接区域的肌球蛋白马达被认为对 MET 很重要。将使用这些新颖的 MEMS 设备在耳蜗中进行新的实验，以表征改变运动活动时发束的力学特征。通过这些实验，将确定分子马达以及耳蜗毛细胞上尖端连接区域在 MET 过程中的作用。在声损伤期间，发束因过度刺激而受到压力，导致发束的硬度变化。为了表征哺乳动物发束的机械特性，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静纤毛链接和静纤毛根对被动发束硬度的贡献。本提案中的实验将进一步加深我们对哺乳动物耳蜗 MET 分子机制的理解。了解被动发束刚度的关键组成部分将为了解发束特性的关键调节点以及声损伤对静纤毛的影响奠定基础。所开发的技术将极大地增强听觉研究，并可能在听觉领域及其他领域有更广泛的力学应用。