Anisotropy links cell shapes to tissue flow during convergent extension

Within developing embryos, tissues flow and reorganize dramatically on timescales as short as minutes. This includes epithelial tissues, which often narrow and elongate in convergent extension movements due to anisotropies in external forces or in internal cell-generated forces. However, the mechani...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS Vol. 117; no. 24; p. 13541
Main Authors: Wang, Xun, Merkel, Matthias, Sutter, Leo B, Erdemci-Tandogan, Gonca, Manning, M Lisa, Kasza, Karen E
Format: Journal Article
Language:English
Published: United States 16.06.2020
Subjects:
Animals
Anisotropy
Cell Shape
Drosophila - cytology
Drosophila - genetics
Drosophila - growth & development
Drosophila - metabolism
Drosophila Proteins - genetics
Drosophila Proteins - metabolism
Epithelium - metabolism
Myosin Type II - genetics
Myosin Type II - metabolism
morphogenesis
epithelia
Drosophila
vertex models
ISSN:1091-6490, 1091-6490
Online Access:Get more information
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Summary:Within developing embryos, tissues flow and reorganize dramatically on timescales as short as minutes. This includes epithelial tissues, which often narrow and elongate in convergent extension movements due to anisotropies in external forces or in internal cell-generated forces. However, the mechanisms that allow or prevent tissue reorganization, especially in the presence of strongly anisotropic forces, remain unclear. We study this question in the converging and extending germband epithelium, which displays planar-polarized myosin II and experiences anisotropic forces from neighboring tissues. We show that, in contrast to isotropic tissues, cell shape alone is not sufficient to predict the onset of rapid cell rearrangement. From theoretical considerations and vertex model simulations, we predict that in anisotropic tissues, two experimentally accessible metrics of cell patterns-the cell shape index and a cell alignment index-are required to determine whether an anisotropic tissue is in a solid-like or fluid-like state. We show that changes in cell shape and alignment over time in the germband predict the onset of rapid cell rearrangement in both wild-type and mutant embryos, where our theoretical prediction is further improved when we also account for cell packing disorder. These findings suggest that convergent extension is associated with a transition to more fluid-like tissue behavior, which may help accommodate tissue-shape changes during rapid developmental events.
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ISSN:1091-6490
1091-6490
DOI:10.1073/pnas.1916418117