Extracellular matrix regulates force transduction at VE-cadherin junctions

Area of Science:

• Cell Biology
• Biophysics
• Mechanobiology

Background:

• Intercellular mechanotransduction involves cell stiffening and cytoskeletal reinforcement.
• VE-cadherin (VE-cad) complexes are crucial for cell-cell adhesion and force transmission.

Purpose of the Study:

• To investigate the downstream effects of VE-cadherin tension on integrin activation.
• To elucidate the role of integrins in reinforcing cadherin adhesions and intercellular force transduction.
• To understand how extracellular matrix (ECM) composition influences this mechanotransduction pathway.

Main Methods:

• Mechanical stimulation of VE-cadherin receptors.
• Analysis of integrin activation and adhesion formation.
• Identification of key signaling molecules (FAK, Abl, RhoA).
• Assessment of ECM substrate effects (collagen, fibronectin) on VE-cad adhesions.

Main Results:

• Tugging VE-cad initiates a cascade leading to integrin activation and new integrin adhesions.
• Integrin activation recruits vinculin and actin, reinforcing VE-cad adhesions.
• Focal adhesion kinase, Abl kinase, and RhoA GTPase are identified as key components in a positive feedback loop.
• Integrin involvement sensitizes intercellular force transduction to the ECM by altering signal cascades, not junctional tension.
• Specific integrins (α2β1, α5β1) differentially control actin remodeling based on ECM type (collagen, fibronectin).

Conclusions:

• Integrins play a critical role in VE-cadherin force transduction, distinct from previously known antagonistic effects.
• A novel mechanism is uncovered where ECM-dependent integrin signaling reinforces interendothelial cell-cell junctions.
• This study highlights a previously unappreciated interaction between integrins, ECM, and cadherin-mediated adhesion reinforcement.