Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto 606-8501, Japan.
Development. 2013 Oct;140(19):4091-101. doi: 10.1242/dev.094060.
Many epithelial tissues pack cells into a honeycomb pattern to support their structural and functional integrity. Developmental changes in cell packing geometry have been shown to be regulated by both mechanical and biochemical interactions between cells; however, it is largely unknown how molecular and cellular dynamics and tissue mechanics are orchestrated to realize the correct and robust development of hexagonal cell packing. Here, by combining mechanical and genetic perturbations along with live imaging and Bayesian force inference, we investigate how mechanical forces regulate cellular dynamics to attain a hexagonal cell configuration in the Drosophila pupal wing. We show that tissue stress is oriented towards the proximal-distal axis by extrinsic forces acting on the wing. Cells respond to tissue stretching and orient cell contact surfaces with the stretching direction of the tissue, thereby stabilizing the balance between the intrinsic cell junction tension and the extrinsic force at the cell-population level. Consequently, under topological constraints of the two-dimensional epithelial sheet, mismatches in the orientation of hexagonal arrays are suppressed, allowing more rapid relaxation to the hexagonal cell pattern. Thus, our results identify the mechanism through which the mechanical anisotropy in a tissue promotes ordering in cell packing geometry.
许多上皮组织将细胞包装成蜂窝状图案，以支持其结构和功能的完整性。细胞包装几何形状的发育变化已被证明受到细胞间机械和生化相互作用的调节；然而，分子和细胞动力学以及组织力学如何协调以实现六边形细胞包装的正确和稳健的发展在很大程度上是未知的。在这里，我们通过结合机械和遗传扰动以及实时成像和贝叶斯力推断，研究了机械力如何调节细胞动力学以在果蝇蛹翅中获得六边形细胞结构。我们表明，组织应力通过作用于翅膀的外在力朝向近-远轴定向。细胞对组织拉伸做出反应，并使细胞接触表面与组织的拉伸方向一致，从而在细胞群体水平上稳定内在细胞连接张力和外在力之间的平衡。因此，在二维上皮片的拓扑限制下，六边形阵列的取向失配被抑制，从而允许更快地松弛到六边形细胞模式。因此，我们的结果确定了组织中的机械各向异性促进细胞包装几何形状有序的机制。
