Anisotropic Cellular Forces Drive Hexagonal-to-Tetragonal Tiling Transitions in the Drosophila Eye.

Area of Science:

• Developmental Biology
• Cellular Mechanics
• Tissue Organization

Background:

• Multicellular epithelial tissues exhibit fundamental tile patterns.
• The Drosophila compound eye displays a hexagonal lattice of ommatidia.
• Previous models failed to explain hexagonal-to-tetragonal pattern transitions in mutants.

Purpose of the Study:

• To identify the mechanisms underlying ommatidial tiling geometry changes.
• To investigate the role of anisotropic cellular forces in epithelial pattern formation.
• To extend vertex models for simulating force-driven morphogenetic transitions.

Main Methods:

• Developed an extended vertex model incorporating dorsoventral stretching and anisotropic forces.
• Utilized computational simulations (in silico analyses).
• Experimentally disrupted radial actin fibers in vivo.

Main Results:

• The extended vertex model successfully recapitulated the hexagonal-to-tetragonal transition in mutant eyes.
• Disruption of radial actin fibers prevented tetragonal pattern formation and caused irregular tiling.
• Anisotropic forces were found to drive tetragonalization in mutants and stabilize hexagonal patterns in wild-type eyes.

Conclusions:

• Anisotropic cellular forces generated by radial actin fibers are crucial for ommatidial tiling geometry.
• The extended vertex model provides a framework for understanding force-driven developmental transitions.
• These findings highlight the dual role of anisotropic forces in epithelial pattern formation.