Membrane properties of the OHC system

耳蜗由多种细胞类型组成，包括感觉、支持和神经元件。 总之，这些细胞组成了一个功能复杂和有凝聚力的电子单位， 分析我们环境中的声音信息。我们利用体外方法， 包括分离的耳蜗外植体、单细胞和最近稳定的细胞系来阐明耳蜗 细胞功能;该策略是在整合到一个有凝聚力的 了解器官。目前，该项目的首要目标是确定 外毛细胞（OHC）的关键膜成分的生物物理特性，是主要的 在听觉功能的球员，使用电生理学，分子生物学，建模和 高分辨率冷冻电镜尽管自上次会议以来，我们在许多方面取得了重大进展， 更新在2010年，我们现在专注于三个具体的研究课题，从我们最重要的发展 成就。特别是，我们调查的主要领域之一一直是并将是 阴离子对OHC分子马达（普雷斯廷，SLC 26 a5）电-机械活性的影响。这 离子是耳蜗放大的根源（Santos-Sacchi等人，2006年）。2012-2016年NIDCD 《战略计划》明确指出，理解听力负离子控制是一个关键目标。三 目的是1）评估OHC非线性电容的氯依赖性动力学行为， 电运动性，2）表征prestin转染的HEK细胞中的细胞内氯离子运动 和OHC与我们创建的新Prestin融合的YFP氯化物传感器，以及3）确定高 普雷斯廷（SLC 26 a5）及其最接近的哺乳动物家族成员SLC 26 a6的解析结构， cryo-EM，目的是识别由于氯化物和电压引起的构象变化。我们 假设理解这些分子活动将有助于理解OHC如何 使我们能够很好地听到微环境的影响如何导致 影响数百万人的OHC。

The cochlea is composed of a variety of cell types including sensory, supporting and neural elements. Taken together, these cells comprise a functionally intricate and cohesive electrical unit that initiates the analysis of acoustic information within our environment. We capitalize on the in vitro approach, including isolated cochlea explants, single cell, and more recently stable cell lines to elucidate cochlear cell function; the strategy is to characterize basic properties prior to integration into a cohesive understanding of the organ. Currently, the overarching aim of this project is focused on determining the biophysical properties of key membrane components of the outer hair cell (OHC), one of the major players in auditory function, using a balance of electrophysiology, molecular biology, modelling and high resolution cryo-EM. Though we have made significant progress on many fronts since our last renewal in 2010, we now focus on three specific research topics that evolve from our most significant accomplishments. In particular, one of the main areas of our investigations has been and will be the influence of anions on the OHC molecular motor’s (prestin, SLC26a5) electro-mechanical activity. This ion is at the root of cochlear amplification (Santos-Sacchi et al., 2006). Indeed, the NIDCD’s 2012-2016 Strategic Plan specifically identifies understanding anion control of hearing as a key goal. The three aims are 1) to evaluate the chloride-dependent kinetic behavior of OHC nonlinear capacitance and electromotility, 2) to characterize intracellular chloride movements in the prestin-transfected HEK cell and OHC with a new prestin-fused YFP chloride sensor we created, and 3) to determine the high resolution structure of prestin (SLC26a5) and its closest mammalian family member SLC26a6 using cryo-EM, with the goal of identifying conformational changes due to chloride and voltage. We hypothesize that understanding these molecular activities will aid in understanding how the OHC enables us to hear so well and in turn how micro-environmental influences may lead to pathologies of the OHC that afflict millions.