HMP-1/α-catenin promotes junctional mechanical integrity during morphogenesis

Area of Science:

• Cell Biology
• Biophysics
• Developmental Biology

Background:

• Adherens junctions (AJs) are crucial for tissue integrity and cell adhesion.
• Actomyosin networks interact with AJs during morphogenesis to drive cell shape and movement.
• Quantitative data on how AJs integrate mechanical forces in vivo is limited.

Purpose of the Study:

• To investigate the spatiotemporal integration of mechanical forces by adherens junctions during embryonic elongation.
• To quantitatively assess the tension on HMP-1/α-catenin using a FRET-based force biosensor in Caenorhabditis elegans.
• To elucidate the regulatory mechanisms and functional roles of HMP-1/α-catenin in maintaining junctional integrity.

Main Methods:

• Insertion of a functional Fluorescence Resonance Energy Transfer (FRET)-based force biosensor into HMP-1/α-catenin in C. elegans.
• Time-lapse analysis of mutant strains and tissue-specific rescue experiments.
• Measurement and analysis of tension distribution on HMP-1/α-catenin and its relationship with the actomyosin network and actin cortex.

Main Results:

• HMP-1/α-catenin tension exhibits cell-specific distribution and is actomyosin-dependent.
• Tension on HMP-1/α-catenin is regulated differently from actin cortex tension during embryonic elongation.
• VAB-9/Claudin acts as an actin bundle anchor, but its absence does not lead to compensatory upregulation of HMP-1 tension.
• HMP-1/α-catenin is required for junctional actin recruitment but not for stress fiber-like actin bundles and does not modulate HMR-1/E-cadherin turnover.

Conclusions:

• HMP-1/α-catenin plays a critical role in promoting the mechanical integrity of adherens junctions.
• The study provides quantitative insights into force integration by AJs during morphogenesis.
• Findings clarify the distinct roles of HMP-1/α-catenin and VAB-9/Claudin in junctional mechanics and actin organization.