Howard Hughes Medical Institute and Laboratory of Sensory Neuroscience, The Rockefeller University , 1230 York Avenue, New York, NY 10065 , USA.
Biol Open. 2012 May 15;1(5):498-505. doi: 10.1242/bio.2012570. Epub 2012 Apr 12.
In addition to their ubiquitous apical-basal polarity, many epithelia are also polarized along an orthogonal axis, a phenomenon termed planar cell polarity (PCP). In the mammalian inner ear and the zebrafish lateral line, PCP is revealed through the orientation of mechanosensitive hair cells relative to each other and to the body axes. In each neuromast, the receptor organ of the lateral line, hair bundles are arranged in a mirror-symmetrical fashion. Here we show that the establishment of mirror symmetry is preceded by rotational rearrangements between hair-cell pairs, a behavior consistently associated with the division of hair-cell precursors. Time-lapse imaging of trilobite mutants, which lack the core PCP constituent Vang-like protein 2 (Vangl2), shows that their misoriented hair cells correlate with misaligned divisions of hair-cell precursors and an inability to complete rearrangements accurately. Vangl2 is asymmetrically localized in the cells of the neuromast, a configuration required for accurate completion of rearrangements. Manipulation of Vangl2 expression or of Notch signaling results in a uniform hair-cell polarity, indicating that rearrangements refine neuromast polarity with respect to the body axes.
除了普遍存在的顶端-基底极性外，许多上皮细胞还沿着正交轴极化，这种现象被称为平面细胞极性（PCP）。在哺乳动物内耳和斑马鱼侧线中，通过机械敏感毛细胞相对于彼此和身体轴的取向来揭示 PCP。在每个毛束中，侧线的感受器器官，毛束以镜像对称的方式排列。在这里，我们表明，镜像对称的建立是通过毛细胞对之间的旋转重排来实现的，这种行为与毛细胞前体的分裂一致。三叶虫突变体的延时成像，缺乏核心 PCP 成分 Vang 样蛋白 2（Vangl2），表明它们错位的毛细胞与毛细胞前体的错位分裂以及无法准确完成重排相关。Vangl2 在毛束细胞中呈不对称定位，这是准确完成重排所需的配置。Vangl2 表达或 Notch 信号转导的操纵导致均匀的毛细胞极性，表明重排相对于身体轴细化了毛束极性。
