Tucker J B, Mackie J B, Bussoli T J, Steel K P
School of Biology, Bute Medical Building, University of St. Andrews, St. Andrews, Fife KY16 9TS, Scotland, UK.
J Neurocytol. 1999 Dec;28(12):1017-34. doi: 10.1023/a:1007092105185.
This report is concerned with control of cell shaping, positioning, and cytoskeletal integration in a highly ordered cochlear neuroepithelium. It is largely based on investigations of events that occur during abnormal morphogenesis of the organ of Corti in the Bronx waltzer (bv/bv) mutant mouse. The organ's sensory hair cells and adjacent supporting cells ordinarily construct a spatially elaborate and supracellularly integrated cytoskeletal framework. Large microtubule bundles are connected to cytoskeletal components in neighbouring cells by actin-containing meshworks that link them to substantial arrays of adherens junctions. In bv/bv mice, degeneration and loss of most inner hair cells and outer pillar cells occurs during organ development. These cells flank each side of a row of inner pillar cells that respond by upregulating assembly of their actin-containing meshworks. This only occurs in surface regions where they no longer contact cell types involved in construction of the cytoskeletal framework. The meshworks are larger and exhibit a more extensive sub-surface deployment than is normally the case. Hence, assembly of intercellular cytoskeletal connecting components can proceed without contact with appropriate cell neighbours but termination of assembly is apparently subject to a negative feedback control triggered by successful completion of intercellular connection with the correct cell neighbours. In addition, inner pillar cells compensate for loss of cell neighbours by interdigitating and overlapping each other more extensively than is usually the case to increase opportunities for generating adherens junctions. Certain adherens junctions in the organs of +/+ and bv/bv mice exhibit features that distinguish them from all previously described cell junctions. The dense plaques on their cytoplasmic faces are composed of aligned ridges. We suggest that they are called ribbed adherens junctions. Perturbations of cell shaping and positioning indicate that loss of inner hair cells is the primary consequence of the bv mutation. Most of the other abnormalities can be understood in terms of a secondary sequence of morphogenetic aberrations (precipitated by loss of inner hair cells). These aberrations provide new information about the ways in which supporting cells help to control hair cell positioning.
本报告关注的是高度有序的耳蜗神经上皮细胞形态塑造、定位及细胞骨架整合的控制。它主要基于对布朗克斯华尔兹（bv/bv）突变小鼠中柯蒂氏器异常形态发生过程中所发生事件的研究。该器官的感觉毛细胞和相邻的支持细胞通常构建一个空间精细且超细胞整合的细胞骨架框架。大型微管束通过含肌动蛋白的网络与相邻细胞中的细胞骨架成分相连，这些网络将它们与大量的黏着连接阵列相连。在bv/bv小鼠中，大多数内毛细胞和外柱细胞在器官发育过程中发生退化和丢失。这些细胞位于一排内柱细胞的两侧，内柱细胞通过上调其含肌动蛋白网络的组装来做出反应。这仅发生在它们不再与参与细胞骨架框架构建的细胞类型接触的表面区域。这些网络比正常情况更大，并且在亚表面的分布更广泛。因此，细胞间细胞骨架连接成分的组装可以在不与合适的细胞邻居接触的情况下进行，但组装的终止显然受到与正确的细胞邻居成功完成细胞间连接所触发的负反馈控制。此外，内柱细胞通过比通常情况更广泛地相互交错和重叠来补偿细胞邻居的丢失，以增加形成黏着连接的机会。+/+和bv/bv小鼠器官中的某些黏着连接表现出与所有先前描述的细胞连接不同的特征。其细胞质面上的致密斑由排列的脊组成。我们建议将它们称为带肋黏着连接。细胞形态塑造和定位的扰动表明内毛细胞的丢失是bv突变的主要后果。大多数其他异常情况可以根据形态发生畸变的继发序列（由内毛细胞的丢失引发）来理解。这些畸变提供了关于支持细胞帮助控制毛细胞定位方式的新信息。
