Amarendra Badugu

How epithelial cells are organized in three dimensions during tissue morphogenesis is poorly understood. In the Drosophila wing imaginal disc, we examined the material factors and mechanical processes that determine the shape of epithelial cells. Since all cells are deposited on a basement membrane which influences the mechanics intracellularly, we reexamined the properties of this structure with fluorescence and transmission electron microscopy. We found regions in which the basement membrane is much thicker than previously reported. We propose that these thickness patterns determine the height and basal surface area of cells and the curvature of the folds in the wing disc. Further, we examined the effect on cell shape and tissue mechanics when disruptions were instigated, at three different time scales: short (seconds, with laser cutting), medium (minutes, with drug treatments) and long (days, with RNAi interference). Disrupting the actin cytoskeleton through drug treatment affects cell shape only at the apical surface while the shapes in the medial plane and at the basal surface were not altered. In contrast, when integrin function was disrupted via RNAi or basement membrane integrity was abolished by drug treatment, medial and basal cell shapes were affected. Based on these findings and previous studies we propose a model of how cell shapes and tissue properties are determined with highly local and modular apical and basal mechanics.

Fig 1: Tissue Architecture, Basement membrane patterns

Fig 2: Quantification of shape parameters in 2.5 dimensions

Fig 5: Application of 2 Photon to abalate Basement membrane contact and cell contacts

Fig 6: Model proposed

Fig S5: Super resolution microscopy application on measurements

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