Abstract：
How pulsed contractile dynamics drive the remodeling of cell and tissue topologies in epithelial sheets has been a key question in development and disease. Due to constraints in imaging and analysis technologies, studies that have described the in vivo mechanisms underlying changes in cell and neighbor relationships have largely been confined to analyses of planar apical regions. Thus, how the volumetric nature of epithelial cells affects force propagation and remodeling of the cell surface in three dimensions, including especially the apical-basal axis, is unclear. Here, we perform lattice light sheet microscopy (LLSM)-based analysis to determine how far and fast forces propagate across different apical-basal layers, as well as where topological changes initiate from in a columnar epithelium. These datasets are highly time- and depth-resolved and reveal that topology-changing forces are spatially entangled, with contractile force generation occurring across the observed apical-basal axis in a pulsed fashion, while the conservation of cell volumes constrains instantaneous cell deformations. Leading layer behaviors occur opportunistically in response to favorable phasic conditions, with lagging layers \"zippering\" to catch up as new contractile pulses propel further changes in cell topologies. These results argue against specific zones of topological initiation and demonstrate the importance of systematic 4D-based analysis in understanding how forces and deformations in cell dimensions propagate in a three-dimensional environment.
摘要：
脉冲收缩动力学如何驱动上皮片中细胞和组织拓扑的重塑一直是发育和疾病的关键问题。由于成像和分析技术的限制，描述了细胞和邻居关系变化的体内机制的研究很大程度上仅限于平面顶端区域的分析。因此，上皮细胞的体积性质如何影响三维细胞表面的力传播和重塑，尤其包括根尖-基轴，不清楚。这里,我们执行晶格光片显微镜（LLSM）为基础的分析，以确定多远和快速的力传播跨不同的根尖基底层，以及从柱状上皮开始的拓扑变化。这些数据集具有高度的时间和深度分辨率，并揭示了拓扑变化力在空间上纠缠，以脉冲方式在观察到的根尖-基轴上产生收缩力，而细胞体积的守恒限制了瞬时细胞变形。领导层行为在有利的阶段性条件下机会主义地发生，随着新的收缩脉冲推动细胞拓扑结构的进一步变化，滞后层“拉链”可以赶上。这些结果与拓扑起始的特定区域相反，并证明了基于4D的系统分析对于理解细胞尺寸中的力和变形如何在三维环境中传播的重要性。
