Flow mechanotransduction regulates traction forces, intercellular forces, and adherens junctions

Area of Science:

• Cell biology
• Biophysics
• Mechanobiology

Background:

• Endothelial cells are sensitive to mechanical forces like fluid shear stress.
• Mechanotransduction pathways regulate endothelial cell cytoskeleton and cell-cell contacts.
• Understanding these responses is crucial for vascular health and disease.

Purpose of the Study:

• To investigate the relationship between fluid shear stress, cytoskeletal tension, intercellular forces, and cell-cell junction assembly in endothelial cells.
• To elucidate how different flow patterns (laminar vs. disturbed) affect endothelial cell mechanotransduction.
• To quantify intercellular forces and their correlation with junctional dynamics.

Main Methods:

• Endothelial cells cultured on micropost arrays exposed to laminar and disturbed flow.
• Measurement of cell traction forces using micropost deflection.
• Pharmacological manipulation of cytoskeletal tension (calyculin-A, Y-27362).
• Novel method developed for measuring intercellular forces across cell-cell junctions.
• Analysis of adherens and tight junction size.

Main Results:

• Laminar flow increased endothelial cell traction forces compared to static conditions.
• Disturbed flow decreased traction forces.
• Adherens junction size positively correlated with traction forces and intercellular forces.
• Intercellular forces were highest under laminar flow and lowest under disturbed flow.
• Pharmacological agents modulating myosin phosphorylation affected adherens junction size.

Conclusions:

• Fluid shear stress differentially regulates endothelial cell cytoskeletal tension.
• Laminar flow enhances cytoskeletal tension, promoting larger cell-cell junctions.
• Disturbed flow reduces cytoskeletal tension, leading to smaller junctions.
• Intercellular forces are a key mediator linking cytoskeletal tension to cell-cell junction assembly in response to shear stress.