Analysis of the function of the protein motor within the outer hair cell motility

外毛细胞运动中蛋白质马达的功能分析

• 批准号: 11307033
• 负责人: WADA Hiroshi
• 金额: $ 24.83万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A).
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11307033/
• 关键词: Outer hair cell; Protein motor; Motility; Atomic force microscope

Although the amplitude of the tympanic membrane vibrations is only a few nanometers when we speak in a low voice, we can understand clearly what is being said. This is speculated to be due to the cochlear amplification which is based on the outer hair cell (OHC) motility, and the motility is estimated to be due to the conformational change of motor proteins within the plasma membrane of the cell. However, the function of the motor protein is unclear, and the effect of the cytoskeleton, which underlies the plasma membrane, on the motility of the cell has not been clarified yet.Therefore, in this study, in order to understand the function of the cell, the deformations of the cell in response to the hypotonic stimulation and the motility of the cell in response to the electrical stimulation are analyzed. Moreover, the ultrastructure of the cell lateral wall is investigated by atomic force microscopy (AFM), and the mechanism of the outer hair cell motility is studied. When the position along the cell axis is represented by the normalized distance from the basal end and the positions of the basal and apical ends are expressed by 0.0 and 1.0, respectively, the following conclusions can be drawn.(1) The longitudinal stiffness of the cell is constant in the region between 0.0 and 0.881 from the basal end, and the stiffness of the cell in the region between 0.881 and 1.0 from the basal end is higher than that in other regions.(2) The distribution of the protein motor along the cell axis is constant in the region between 0.142 and 0.893, and in the other regions at the apical and basal parts of the cell, the protein motor does not exist.(3) The circumferential filaments, which would be actins in the cortical lattice, are observed by AFM, and the density of the circumferential filaments at the apical part, where the stiffness is high, is higher than that at the basal part.

虽然当我们低声说话时，鼓膜振动的幅度只有几纳米，但我们可以清楚地理解正在说的话。这被推测是由于耳蜗放大，这是基于外毛细胞（OHC）的运动性，和运动性估计是由于构象变化的马达蛋白在质膜的细胞。然而，由于运动蛋白的功能尚不清楚，质膜下的细胞骨架对细胞运动性的影响也不清楚，因此，为了了解细胞的功能，本研究分析了低渗刺激下细胞的变形和电刺激下细胞的运动性。此外，还利用原子力显微镜（AFM）观察了外毛细胞侧壁的超微结构，探讨了外毛细胞运动的机制。当沿细胞轴的沿着位置由距基端的归一化距离表示并且基端和顶端的位置分别由0.0和1.0表示时，可以得出以下结论。(1)在距基端0.0 ~ 0.881的区域内，单元的纵向刚性恒定，距基端0.881 ~ 1.0的区域内的单元的刚性比其他区域高。(2)蛋白马达沿着细胞轴的分布在0.142和0.893之间的区域中是恒定的，并且在细胞的顶部和基部的其它区域中，蛋白马达不存在。(3)用原子力显微镜观察到皮质晶格中的周向纤维，即肌动蛋白，刚度较高的顶端部分的周向纤维密度高于基部。