Mechanotransduction and calcium regulation in cochlear hair cells

耳蜗毛细胞的力传导和钙调节

• 批准号: 9294999
• 负责人: Ruben Stepanyan
• 金额: $ 33.68万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-15 至 2021-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9294999
• 关键词: Acoustics; Affect; Age; American; Apical; Auditory; Auditory Brainstem Responses; Binding; Bioenergetics; Biological Assay; Buffers; Ca(2+)-Transporting ATPase; Calcium; Calcium ion; Cell Death; Cell Survival; Cell membrane; Cell physiology; Cells; Cessation of life; Clinical; Complement; Cytosol; Data; Electron Microscopy; Equilibrium; Event; Excision; Exposure to; Frequencies; Functional disorder; Genetic study; Goals; Hair; Hair Cells; Homeostasis; Image; Impairment; In Vitro; Inner mitochondrial membrane; Investigation; Knockout Mice; Labyrinth; Lead; Leisure Activities; Link; Mechanical Stimulation; Mechanics; Mitochondria; Monitor; Morphology; Mus; Noise; Noise-Induced Hearing Loss; Outer Hair Cells; Oxidation-Reduction; Oxidative Stress; Pathologic; Pathway interactions; Peptides; Pharmacology; Physical shape; Play; Process; Public Health; Receptor Cell; Recovery of Function; Regulation; Reporting; Research; Resolution; Role; Sensory; Sensory Receptors; Structure; Testing; Wild Type Mouse; Work; base; cell injury; experimental study; feeding; hearing impairment; improved; in vivo; mechanotransduction; mitochondrial metabolism; mouse model; novel; novel strategies; otoacoustic emission; oxidative damage; patch clamp; response; sound; uptake; vibration

ABSTRACT Noise can irreversibly damage the sensory receptors of the inner ear, the hair cells, and lead to permanent hearing loss. Hair cells respond to sound-induced mechanical vibrations with inward current, passing through mechanotransduction channels at the tips of stereocilia. In response to stereocilia deflections, calcium ions enter the cell, bind to fixed and mobile buffers and are extruded by cell membrane calcium pumps. The basal, high frequency outer hair cells have relatively few calcium pumps. Thus, mitochondria, which are concentrated in a belt beneath the cuticular plate, a support structure for stereocilia, may play a major role in calcium removal during mechanical stimulation in these cells. The goal of this study is to understand how mechanical overstimulation impairs mechanotransduction, perturbs calcium balance, and disrupts redox homeostasis in cochlear hair cells. This will aid in understanding why basal, high frequency outer hair cells are more susceptible to noise exposure than apical, low frequency ones. In addition we will test a novel strategy to increase hair cell viability by protecting their mitochondria from calcium overload and oxidative damage. The first aim of our proposal is to determine changes in hair cell mechanotransduction function following mechanical overstimulation. Our preliminary data show significant calcium increases in the basal, high frequency outer hair cells during mechanical stimulation. Calcium was promptly removed from the cytosol following stimulation, while mitochondrial calcium overload was sustained. Because an increase in mitochondrial calcium is commonly reported in cell death pathways, a study of hair cells' mitochondrial calcium balance following overstimulation is necessary. Within the second aim, we will use a knockout mouse model with impaired mitochondrial calcium uptake to determine whether mitochondrial calcium overload is required for oxidative stress in hair cells following overstimulation. When overloaded with Ca, mitochondria undergo oxidative damage; this will further increase oxidative stress, initiating a feed-forward cycle to further damage mitochondria. We will test the hypothesis that mitochondrial calcium overload and dysfunction in outer hair cells contribute to the vulnerability of these sensory cells to overstimulation. To complement our genetic studies, we will also examine whether protecting mitochondria against calcium overload and oxidative stress will increase hair cell viability by using a pharmacological approach: we will use novel Szeto-Schiller peptides that concentrate to the inner mitochondrial membrane to protect mitochondria from oxidative damage and improve mitochondrial bioenergetics. In summary, our study will reveal how mechanical overstimulation can damage the stereociliary bundle and impair its function. In addition, this study will establish the role of mitochondrial Ca2+ overload in hair cell dysfunction and death, providing not only a mechanistic understanding of the process, but possibly paving the way for a novel clinical strategy to protect cochlear hair cells.

抽象的 噪声会不可逆地损害内耳，毛细胞的感觉受体，并导致 永久听力损失。毛细胞以内向电流对声音诱导的机械振动做出反应， 通过立体尾尖的机械转导通道。响应立体胶质 偏转，钙离子进入细胞，与固定和移动缓冲液结合，并被细胞膜挤出 钙泵。基础高频外毛细胞的钙泵相对较少。那， 线粒体集中在可爱板下方的皮带上，是一个支撑结构 在这些细胞中的机械刺激过程中，立体胶质可能在去除钙的去除中起主要作用。目标 这项研究的是了解机械过度刺激如何损害机械转移，Perturbs 钙平衡，并破坏耳蜗细胞中的氧化还原稳态。这将有助于理解为什么 基础，高频外毛细胞比顶部低频更容易受到噪声的影响 一个。此外，我们将通过保护线粒体来测试一种新的策略，以提高毛细胞活力 来自钙超负荷和氧化损伤。我们建议的第一个目的是确定头发的变化 机械过度刺激后的细胞机械传导功能。我们的初步数据显示 机械刺激期间，基本高频外毛细胞的钙显着增加。 刺激后迅速从细胞质中取出钙，而线粒体钙超负荷 因为在细胞死亡途径中通常报告了线粒体钙的增加，所以 过度刺激后，对毛细胞的线粒体钙平衡的研究是必要的。在 第二个目的，我们将使用带有线粒体钙摄取受损的敲除鼠标模型来确定 是否需要线粒体钙过载，以使毛细胞中氧化应激需要 过度刺激。当与CA重载时，线粒体会受到氧化物的损害；这将进一步 增加氧化应激，启动前馈周期以进一步损害线粒体。我们将测试 假设线粒体钙过载和外毛细胞功能障碍有助于 这些感觉细胞过度刺激的脆弱性。为了补充我们的遗传研究，我们也将 检查是否保护线粒体免受钙超负荷和氧化应激会增加头发 通过使用药物方法的细胞活力：我们将使用新型的szeto-shiller肽 浓缩到内部线粒体膜，以保护线粒体免受氧化损伤和 改善线粒体生物能学。总而言之，我们的研究将揭示机械过度刺激如何 损坏立体束并损害其功能。此外，这项研究将确定 线粒体Ca2+毛细胞功能障碍和死亡中的过载，不仅提供机械 了解该过程，但可能为保护人耳蜗的新型临床策略铺平了道路 毛细胞。