Hbs and Rst adhesion molecules provide a regional code that regulates cell elimination during epithelial remodeling.

Area of Science:

• Developmental Biology
• Cell Biology
• Mechanobiology

Background:

• Epithelial tissue architecture is shaped by cellular interactions and mechanical forces.
• Tissue compression at the Drosophila notum midline promotes epithelial cell elimination.

Purpose of the Study:

• To identify regulators of epithelial remodeling in the Drosophila notum.
• To investigate the role of cell adhesion proteins Hibris (Hbs) and Roughest (Rst) in epithelial cell elimination.

Main Methods:

• Multi-step RNAi screen to identify regulators of notum epithelial remodeling.
• Analysis of Hbs and Rst expression patterns in relation to cell survival and pruning zones.
• Genetic manipulation (knock-down, overexpression, local suppression) of Hbs and Rst.

Main Results:

• Identified 47 diverse regulators of notum epithelial remodeling.
• Hbs and Rst expression inversely correlates with cell pruning and survival zones.
• Notum-wide Hbs/Rst knock-down or Hbs overexpression disrupts cell death and causes malformations.
• Local suppression of Hbs/Rst induces ectopic cell elimination, indicating their instructive role in cell removal.
• Hbs, but not Rst, is regulated by compaction-sensitive EGFR signaling.

Conclusions:

• Hbs and Rst play a crucial role in regulating epithelial cell elimination during tissue compression.
• Hbs integrates mechanical cues (compaction) and cell property cues via EGFR signaling.
• These findings reveal a novel adhesive landscape governing thorax midline development and potentially other organs.