Cellular Neurobiology Research Unit, Institut de recherches cliniques de Montréal (IRCM), Montreal, QC H2W 1R7, Canada.
Dev Cell. 2013 Oct 14;27(1):88-102. doi: 10.1016/j.devcel.2013.09.011.
Sound perception relies on the planar polarization of the mechanosensory hair cell apex, which develops a V-shaped stereocilia bundle pointing toward an eccentric kinocilium. It remains unknown how intrinsically asymmetric bundles arise and are concomitantly oriented in the tissue. We report here that mInsc, LGN, and Gαi proteins, which classically regulate mitotic spindle orientation, are polarized in a lateral microvilli-free region, or "bare zone," at the apical hair cell surface. By creating and extending the bare zone, these proteins trigger a relocalization of the eccentric kinocilium midway toward the cell center. aPKC is restrained medially by mInsc/LGN/Gαi, resulting in compartmentalization of the apical surface that imparts the V-shaped distribution of stereocilia and brings the asymmetric bundle in register with the relocalized kinocilium. Gαi is additionally required for lateral orientation of cochlear hair cells, providing a possible mechanism to couple the emergence of asymmetric stereocilia bundles with planar cell polarity.
声音感知依赖于机械敏感毛细胞顶端的平面偏振，其形成指向偏心的静纤毛的 V 形纤毛束。目前尚不清楚内在不对称束如何产生并在组织中同时定向。我们在此报告，经典地调节有丝分裂纺锤体取向的 mInsc、LGN 和 Gαi 蛋白在顶端毛细胞表面的无侧向微绒毛区域或“裸区”中呈极化状态。通过创建和扩展裸区，这些蛋白引发偏心静纤毛向细胞中心的中途重新定位。aPKC 被 mInsc/LGN/Gαi 约束在中间，导致顶表面的分隔，赋予纤毛的 V 形分布，并使不对称束与重新定位的静纤毛对准。Gαi 还需要耳蜗毛细胞的侧向定向，为将不对称纤毛束的出现与平面细胞极性偶联提供了一种可能的机制。
