IQGAP1 regulates endothelial barrier function via EB1-cortactin cross talk

Area of Science:

• Cell Biology
• Cytoskeletal Dynamics
• Vascular Biology

Background:

• Actin cytoskeleton and microtubule (MT) cross talk influences Rho signaling and vascular endothelial permeability.
• Hepatocyte growth factor (HGF) is known to affect endothelial barrier properties.

Purpose of the Study:

• To investigate the role of actin-MT cross talk in HGF-induced endothelial barrier enhancement.
• To determine the function of IQGAP1 in integrating MT- and actin-dependent pathways during HGF signaling.

Main Methods:

• Small interfering RNA (siRNA) for IQGAP1 knockdown.
• Assessment of endothelial barrier properties.
• Analysis of cortical actin dynamics and MT growth.
• Co-immunoprecipitation to identify protein complexes.

Main Results:

• IQGAP1 knockdown attenuated HGF-induced barrier enhancement and abolished cortical actin dynamics.
• IQGAP1 reduction inhibited peripheral accumulation of cortactin and actin remodeling.
• HGF stimulated MT growth in an IQGAP1-dependent manner, involving EB1, IQGAP1, and cortactin complex formation.

Conclusions:

• HGF-induced endothelial barrier enhancement involves a novel MT-actin cross talk mechanism.
• IQGAP1 acts as a central hub, linking HGF signaling to cytoskeletal remodeling via EB1-IQGAP1-cortactin interactions.