A labile pool of IQGAP1 disassembles endothelial adherens junctions

Area of Science:

• Endothelial cell biology
• Molecular cell adhesion
• Cytoskeletal dynamics

Background:

• Adhesion molecules are critical for endothelial activation and angiogenesis.
• Endothelial adherens junctions regulate vascular integrity.
• IQGAP1's role in endothelial cell-cell adhesion is not fully understood.

Purpose of the Study:

• To investigate the functional role of IQGAP1 in regulating endothelial adherens junctions.
• To determine how IQGAP1 affects the stability and dynamics of VE-cadherin at intercellular junctions.

Main Methods:

• Utilized human umbilical vein endothelial cells (HUVECs).
• Assessed the association of IQGAP1 with actin filaments and intercellular junctions.
• Examined the impact of IQGAP1 knockdown on VE-cadherin, P120, and β-catenin interactions.
• Measured electrical resistance across HUVEC monolayers to assess barrier function.

Main Results:

• IQGAP1 at intercellular junctions is labile and not actin-bound, unlike stable VE-cadherin.
• Expression of VE-α-catenin increased electrical resistance and reduced labile IQGAP1.
• Knockdown of IQGAP1 enhanced endothelial cell-cell adhesion by increasing VE-cadherin association with P120 and β-catenin.
• IQGAP1 knockdown decreased N-cadherin interactions with P120 and β-catenin.

Conclusions:

• A labile pool of IQGAP1 at intercellular junctions disassembles adherens junctions.
• IQGAP1 negatively regulates endothelial cell-cell adhesion and barrier integrity.
• Targeting IQGAP1 may offer therapeutic strategies for vascular permeability disorders.