Rho family GTPases regulate VEGF-stimulated endothelial cell motility

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Endothelial cell migration is essential for angiogenesis, a process regulated by growth factors like vascular endothelial growth factor (VEGF) and extracellular matrix (ECM) interactions.
• Signal transduction pathways linking growth factor stimulation and ECM interactions are critical for controlling endothelial cell motility.

Purpose of the Study:

• To investigate the role of Rho family GTPases in endothelial cell chemotaxis stimulated by VEGF and haptotaxis stimulated by type 1 collagen.
• To identify the specific GTPases involved in these migratory processes and their downstream effects.

Main Methods:

• Human foreskin dermal endothelial cells were transduced with Rho family GTPase fusion proteins using a Tat peptide delivery system.
• VEGF-stimulated chemotaxis and type 1 collagen-stimulated haptotaxis were analyzed.
• Activation of Rac, Cdc42, and Rho GTPases was assessed, along with changes in stress fibers and focal adhesions.

Main Results:

• Rac GTPase activation was required for VEGF-stimulated chemotaxis and was also activated during haptotaxis on type 1 collagen.
• Both Rac and Cdc42 GTPases were activated during haptotaxis on type 1 collagen.
• Surprisingly, Rho GTPase activation was not observed in collagen-induced haptotaxis or VEGF-stimulated chemotaxis, and its constitutive activation inhibited haptotaxis.

Conclusions:

• Rac GTPase is a critical intersection point for both VEGF- and type 1 collagen-mediated endothelial cell motility.
• Rac is both necessary and sufficient for activating endothelial cell haptotaxis and VEGF-stimulated chemotaxis.
• These findings elucidate the specific roles of Rho family GTPases in endothelial cell migration during angiogenesis.