Peng Anthony W, Scharr Alexandra L, Caprara Giusy A, Nettles Dailey, Steele Charles R, Ricci Anthony J
Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States.
Department of Otolaryngology, Head and Neck Surgery, School of Medicine, Stanford University, Stanford, CA, United States.
Front Cell Dev Biol. 2021 Aug 26;9:725101. doi: 10.3389/fcell.2021.725101. eCollection 2021.
Hair cell mechanosensitivity resides in the sensory hair bundle, an apical protrusion of actin-filled stereocilia arranged in a staircase pattern. Hair bundle deflection activates mechano-electric transduction (MET) ion channels located near the tops of the shorter rows of stereocilia. The elicited macroscopic current is shaped by the hair bundle motion so that the mode of stimulation greatly influences the cell's output. We present data quantifying the displacement of the whole outer hair cell bundle using high-speed imaging when stimulated with a fluid jet. We find a spatially non-uniform stimulation that results in splaying, where the hair bundle expands apart. Based on modeling, the splaying is predominantly due to fluid dynamics with a small contribution from hair bundle architecture. Additionally, in response to stimulation, the hair bundle exhibited a rapid motion followed by a slower motion in the same direction (creep) that is described by a double exponential process. The creep is consistent with originating from a linear passive system that can be modeled using two viscoelastic processes. These viscoelastic mechanisms are integral to describing the mechanics of the mammalian hair bundle.
毛细胞的机械敏感性存在于感觉毛束中，感觉毛束是由充满肌动蛋白的静纤毛组成的顶端突起，呈阶梯状排列。毛束的偏转激活位于较短静纤毛排顶部附近的机械电转导（MET）离子通道。引发的宏观电流由毛束运动塑造，因此刺激模式极大地影响细胞的输出。我们展示了在流体喷射刺激下使用高速成像对整个外毛细胞束位移进行量化的数据。我们发现一种空间上不均匀的刺激会导致毛束张开，即毛束向外扩张。基于建模，毛束张开主要是由于流体动力学，毛束结构的贡献较小。此外，响应刺激时，毛束表现出快速运动，随后是沿相同方向的较慢运动（蠕动），这一过程可用双指数过程来描述。这种蠕动与源于线性被动系统一致，该系统可用两个粘弹性过程来建模。这些粘弹性机制对于描述哺乳动物毛束的力学特性不可或缺。
