Rac1/RhoA antagonism defines cell-to-cell heterogeneity during epidermal morphogenesis in nematodes

Area of Science:

• Developmental Biology
• Cell Biology
• Genetics

Background:

• The GTPases Rac1 and RhoA are known to regulate cell-cell heterogeneity and epithelial morphogenesis.
• Their specific roles in epidermal morphogenesis and cell-to-cell heterogeneity have not been previously investigated.

Purpose of the Study:

• To investigate the involvement of Rac1 and RhoA antagonism in epidermal morphogenesis and cell-to-cell heterogeneity.
• To characterize the molecular pathways controlling cell shape and junction dynamics during embryonic development.

Main Methods:

• Quantitative cell imaging was employed to analyze epidermal morphogenesis at a single-cell level.
• The study focused on early elongation stages of Caenorhabditis elegans embryos.

Main Results:

• A Rac1-like pathway (β-PIX/PIX-1 and PAK1/PAK-1) and a RhoA-like pathway (ROCK/LET-502) were identified as key regulators.
• These pathways control apical junction remodeling and basolateral protrusion formation (lamellipodia or amoeboid).
• Cell-autonomous antagonism between these pathways allows cells to switch between morphogenetic programs.

Conclusions:

• This study reveals the first instance of cell-to-cell heterogeneity controlled by Rac1/RhoA antagonism during epidermal morphogenesis.
• The findings suggest that lamella formation may alleviate junctional tension during morphogenesis.
• Distinct subsets of hypodermal cells utilize these antagonistic pathways to achieve specific morphogenetic outcomes.