Cell adhesion and cortex contractility determine cell patterning in the Drosophila retina

TL;DR

This study investigates how cell adhesion and cortex contractility influence cell packing and shape in the Drosophila retina, proposing a model that incorporates surface tension and contractility to explain experimental observations.

Contribution

The paper introduces a novel model combining adhesion-driven surface increase with cortex contraction to accurately simulate cell packing and shapes in the Drosophila retina.

Findings

The model reproduces wildtype cell packing and shapes.

It explains mutant phenotypes with altered cadherin expression.

Surface minimization alone is insufficient to explain cell packing.

Abstract

Hayashi and Carthew (Nature 431 [2004], 647) have shown that the packing of cone cells in the Drosophila retina resembles soap bubble packing, and that changing E- and N-cadherin expression can change this packing, as well as cell shape. The analogy with bubbles suggests that cell packing is driven by surface minimization. We find that this assumption is insufficient to model the experimentally observed shapes and packing of the cells based on their cadherin expression. We then consider a model in which adhesion leads to a surface increase, balanced by cell cortex contraction. Using the experimentally observed distributions of E- and N-cadherin, we simulate the packing and cell shapes in the wildtype eye. Furthermore, by changing only the corresponding parameters, this model can describe the mutants with different numbers of cells, or changes in cadherin expression.