Differential positioning of adherens junctions is associated with initiation of epithelial folding
Open Access
- 28 March 2012
- journal article
- research article
- Published by Springer Science and Business Media LLC in Nature
- Vol. 484 (7394), 390-393
- https://doi.org/10.1038/nature10938
Abstract
Shifts in the position of adherens junctions, triggered by a change in the ratio of Bazooka and Par-1, initiate epithelial folding in the Drosophila embryo. The prevailing model for epithelial folding during tissue morphogenesis involves cell-shape changes driven by shrinking of the apical side of cells. Here, Eric Wieschaus and colleagues present an alternative mechanism that takes place during gastrulation in Drosophila. They find that differential positioning of adherens junctions, regulated by polarity proteins, facilitates tissue deformation. This study establishes a direct link between modification of epithelial polarity and initiation of epithelial folding during development. During tissue morphogenesis, simple epithelial sheets undergo folding to form complex structures. The prevailing model underlying epithelial folding involves cell shape changes driven by myosin-dependent apical constriction1. Here we describe an alternative mechanism that requires differential positioning of adherens junctions controlled by modulation of epithelial apical–basal polarity. Using live embryo imaging, we show that before the initiation of dorsal transverse folds during Drosophila gastrulation, adherens junctions shift basally in the initiating cells, but maintain their original subapical positioning in the neighbouring cells. Junctional positioning in the dorsal epithelium depends on the polarity proteins Bazooka and Par-1. In particular, the basal shift that occurs in the initiating cells is associated with a progressive decrease in Par-1 levels. We show that uniform reduction of the activity of Bazooka or Par-1 results in uniform apical or lateral positioning of junctions and in each case dorsal fold initiation is abolished. In addition, an increase in the Bazooka/Par-1 ratio causes formation of ectopic dorsal folds. The basal shift of junctions not only alters the apical shape of the initiating cells, but also forces the lateral membrane of the adjacent cells to bend towards the initiating cells, thereby facilitating tissue deformation. Our data thus establish a direct link between modification of epithelial polarity and initiation of epithelial folding.This publication has 30 references indexed in Scilit:
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