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

Area of Science:

• Developmental Biology
• Biophysics
• Cell Biology

Background:

• Epithelial tissues share structural similarities with packed soap bubbles, leading to the hypothesis that surface minimization principles govern cell packing.
• Understanding the biophysical forces that dictate cell shape and arrangement is crucial for comprehending tissue development and function.

Purpose of the Study:

• To investigate whether surface minimization is sufficient to model cell packing and shape in the Drosophila retina.
• To develop and validate a biophysical model that accurately describes cell packing and shape based on cadherin expression and mechanical properties.

Main Methods:

• Computational modeling of cell shapes and packing in Drosophila ommatidia.
• Analysis of wild-type and mutant fly retinas with varying cell numbers and cadherin (E-cadherin and N-cadherin) expression levels.
• Comparison of model predictions with experimental observations of cell configurations and shapes.

Main Results:

• Surface minimization alone was insufficient to replicate experimentally observed cell shapes and packing.
• A refined model, incorporating adhesion-induced surface changes balanced by cell cortex contraction, successfully predicted wild-type Drosophila eye cell packing and shapes.
• This refined model accurately described mutant phenotypes by adjusting specific parameters related to cell number and cadherin expression.

Conclusions:

• Simple surface minimization is inadequate for explaining epithelial cell packing dynamics.
• A more complex biophysical model integrating adhesion and cortical tension is necessary to accurately predict cell shape and arrangement in developing tissues.
• Cadherin-mediated adhesion and cell cortex mechanics are key determinants of epithelial tissue morphology.