Yan Keji, Qu Chengli, Wang Yanfei, Zong Wen, Xu Zhigang
Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China.
State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China.
Front Mol Neurosci. 2022 Feb 15;15:829204. doi: 10.3389/fnmol.2022.829204. eCollection 2022.
Hair cells are mechanosensitive cells in the inner ear, characterized by dozens to hundreds of actin-based stereocilia and one tubulin-based kinocilium on the apical surface of each cell. Two types of hair cells, namely cochlear hair cells and vestibular hair cells (VHCs), are responsible for the sensation of sound and balancing information, respectively. In each hair cell, the stereocilia are organized into rows of increasing heights with the mechano-electrical transduction (MET) channels localized at the tips of shorter-row stereocilia. A so-called "row 2 protein complex" also localizes at the tips of shorter-row mechanotransducing stereocilia, which plays important roles in the maintenance of mechanotransducing stereocilia. Recently, we and others identified BAIAP2L2 as a new component of row 2 complex. inactivation causes degeneration of the mechanotransducing stereocilia in cochlear hair cells, and leads to profound hearing loss in mice. In the present work, we examined the role of BAIAP2L2 in the VHC stereocilia. Confocal microscopy reveals that BAIAP2L2 immunoreactivity is localized at the tips of shorter-row stereocilia in VHCs. However, stereocilia development and maintenance are unaffected in VHCs. Meanwhile, MET function of VHCs as well as vestibular functions are also unaffected in mice. Further investigations show that the stereociliary tip localization of CAPZB2, another known row 2 complex component, is not affected in VHCs, consistent with the unaltered stereocilia morphology. Taken together, our present data show that BAIAP2L2 inactivation does not affect vestibular hair cell stereocilia.
毛细胞是内耳中的机械敏感细胞，其特征是每个细胞的顶端表面有数十到数百根基于肌动蛋白的静纤毛和一根基于微管蛋白的动纤毛。两种类型的毛细胞，即耳蜗毛细胞和前庭毛细胞（VHC），分别负责声音感知和平衡信息。在每个毛细胞中，静纤毛排列成高度递增的行，机械电转导（MET）通道位于较短行静纤毛的顶端。一种所谓的“第2排蛋白复合物”也位于较短行机械转导静纤毛的顶端，它在维持机械转导静纤毛方面发挥着重要作用。最近，我们和其他人将BAIAP2L2鉴定为第2排复合物的一个新成分。BAIAP2L2失活会导致耳蜗毛细胞中机械转导静纤毛退化，并导致小鼠严重听力损失。在本研究中，我们研究了BAIAP2L2在前庭毛细胞静纤毛中的作用。共聚焦显微镜显示，BAIAP2L2免疫反应性定位于前庭毛细胞较短行静纤毛的顶端。然而，前庭毛细胞的静纤毛发育和维持不受影响。同时，前庭毛细胞的MET功能以及小鼠的前庭功能也不受影响。进一步研究表明，另一种已知的第2排复合物成分CAPZB2的静纤毛顶端定位在前庭毛细胞中不受影响，这与静纤毛形态未改变一致。综上所述，我们目前的数据表明BAIAP2L2失活不会影响前庭毛细胞静纤毛。
