Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, 01307 Dresden, Germany.
Curr Biol. 2012 Jul 24;22(14):1296-301. doi: 10.1016/j.cub.2012.04.066. Epub 2012 Jun 21.
Epithelial tissues develop planar polarity that is reflected in the global alignment of hairs and cilia with respect to the tissue axes. The planar cell polarity (PCP) proteins form asymmetric and polarized domains across epithelial junctions that are aligned locally between cells and orient these external structures. Although feedback mechanisms can polarize PCP proteins intracellularly and locally align polarity between cells, how global PCP patterns are specified is not understood. It has been proposed that the graded distribution of a biasing factor could guide long-range PCP. However, we recently identified epithelial morphogenesis as a mechanism that can reorganize global PCP patterns; in the Drosophila pupal wing, oriented cell divisions and rearrangements reorient PCP from a margin-oriented pattern to one that points distally. Here, we use quantitative image analysis to study how PCP patterns first emerge in the wing. PCP appears during larval growth and is spatially oriented through the activities of three organizer regions that control disc growth and patterning. Flattening morphogen gradients emanating from these regions does not reduce intracellular polarity but distorts growth and alters specific features of the PCP pattern. Thus, PCP may be guided by morphogenesis rather than morphogen gradients.
上皮组织发育出平面极性，这反映在毛发和纤毛相对于组织轴的整体排列上。平面细胞极性 (PCP) 蛋白在跨上皮连接形成不对称和极化的域，这些域在细胞之间局部对齐，并使这些外部结构定向。尽管反馈机制可以在细胞内极化 PCP 蛋白并在细胞之间局部对齐极性，但全球 PCP 模式是如何指定的尚不清楚。有人提出，偏置因子的梯度分布可以指导长程 PCP。然而，我们最近发现上皮形态发生是一种可以重新组织全球 PCP 模式的机制；在果蝇蛹翅中，定向细胞分裂和重排将 PCP 从边缘定向模式重新定向到指向远端的模式。在这里，我们使用定量图像分析来研究 PCP 模式如何首先出现在翅膀中。PCP 在幼虫生长过程中出现，并通过控制盘生长和图案形成的三个组织者区域的活动在空间上定向。从这些区域发出的扁平化形态发生梯度不会减少细胞内极性，但会改变生长并改变 PCP 模式的特定特征。因此，PCP 可能由形态发生而不是形态发生梯度引导。
