Biomechanics of Vertebrate Hair Cells

发孔是脊椎动物感知声音、头部运动、振动和重力的感受器。每一种感觉都始于机械刺激。毛细胞通过一个复杂的细胞过程对这种刺激作出反应，形成中枢神经系统的主要传入信号。这个过程的第一步，也是所有其他步骤所依赖的，是毛细胞纤毛束的偏转。不幸的是，控制这第一个关键步骤的机械和细胞机制尚不清楚。这项研究的长期目标是了解毛细胞机械转导的基本机制，并建立这一过程的现实计算模型。这是一项使用最先进的成像和计算技术的生物工程合作项目。拟议的研究有三个生物工程的努力，使用最先进的成像和计算技术。拟议的研究有三个具体目标。(1)我们将使用光学和电子显微镜技术定量表征毛细胞的结构，强调可能影响毛细胞机械性能的纤毛束的特征，我们将使用明场和共聚焦显微镜来可视化毛束与活细胞中覆盖的耳石膜之间的耦合。(2)我们将把这些数据整合到纤毛束的结构精确有限元模型中，该模型将量化不同结构元素（例如，立体纤毛的数量、高度和相互连接）和体内刺激对毛细胞形态不同品种的静态刚度和响应动力学的贡献。然后，我们将通过对活束的实验测试来测试和完善我们的模型预测。(3)我们将使用我们的计算模型来预测不同类型束中的电流-位移关系。然后，我们将使用活毛细胞的全细胞膜片钳记录来进一步测试和完善我们的模型预测。这些研究将为纤毛束结构的机械转导机制和功能意义提供重要信息。由此产生的计算模型将是未来试图理解任何脊椎动物毛细胞力学性能的强大资源。

Hair dells are the receptors that vertebrates us to detect sound, head movement, vibrations, and gravity. Each of these sensations begins with a mechanical stimulus. Hair cells respond to this stimulus via a complex cellular process that shapes the primary afferent signal to the central nervous system. The first step in this process and the one on which all others depend is deflect of the hair cell's ciliary bundle. Unfortunately, the mechanical and cellular mechanisms that govern this first critical step are poorly understood. The long term goal of the proposed research is to understand these fundamental mechanisms of mechanotransduction by hair cells and to develop a realistic computational model of this process. It is a collaborative bioengineering effort that uses state-of-the-art imaging and computational technology. The proposed research has three bioengineering effort that uses state-of-the-art imaging and computational technology. The proposed research has three Specific Aims. (1) We will use light and electron microscopic techniques to characterize quantitatively the structure of hair cells, emphasizing those features of their ciliary bundles that are likely to affect the hair ells' mechanical performance, and we will use brightfield and confocal microscopy to visualize the coupling between hair bundles and the overlying otolithic membranes in living utricles. (2) We will incorporate these data into a structurally accurate finite element model of the ciliary bundle that will quantify the contribution of different structural elements (e.g., number, height, and interconnections of stereocilia) and the in vivo stimulus to the static stiffness and response dynamics of morphologically distinct varieties of hair cells. Then we will test and refine our model predictions by experimental tests on living bundles. (3) We will use our computational model to predict current-displacement relations in bundles of different types. Then we will use whole-cell patch clamp recording from living hair cells to further test and refine our model predictions. These studies will provide, important information about mechanisms of mechanotransduction and the functional significance of ciliary bundle structure. The resulting computational model will be a powerful resource in future attempts to understand the mechanical performance of any vertebrate hair cells.