VEGF-A isoforms differentially regulate ATF-2-dependent VCAM-1 gene expression and endothelial-leukocyte interactions

Area of Science:

• Molecular biology
• Cellular signaling
• Vascular physiology

Background:

• Vascular endothelial growth factor A (VEGF-A) is vital for vascular physiology, controlling endothelial cell behaviors like migration and proliferation.
• The functional significance of different VEGF-A isoforms remains incompletely understood.
• VCAM-1 gene expression regulates endothelial-leukocyte interactions, a key aspect of vascular responses.

Purpose of the Study:

• To investigate the isoform-specific effects of VEGF-A on VCAM-1 gene expression.
• To elucidate the roles of ERK1/2 and activating transcription factor-2 (ATF-2) in VEGF-A-mediated signaling.
• To understand how VEGF-A isoforms program distinct cellular outputs.

Main Methods:

• Analysis of VEGF-A isoform-specific stimulation of VCAM-1 gene expression.
• Assessment of ERK1/2 and p38 MAPK phosphorylation kinetics.
• Investigation of ATF-2 phosphorylation at threonine 71 (T71).
• Utilizing reverse genetics (ATF-2 knockdown) to determine functional requirements.

Main Results:

• VEGF-A isoforms exhibited differential activation kinetics of ERK1/2 and p38 MAPK.
• Increased phosphorylation of ATF-2 at T71 was a key feature of VEGF-A isoform-specific ERK1/2 activation.
• ATF-2 was functionally essential for VEGF-A-stimulated VCAM-1 expression and endothelial-leukocyte interactions.
• ATF-2 knockdown abrogated VEGF-A-induced VCAM-1 expression and cell migration.
• VCAM-1 was specifically required for endothelial-leukocyte interactions, unlike ATF-2's broader role.

Conclusions:

• VEGF-A isoforms differentially regulate endothelial cell responses through distinct signaling pathways.
• The phosphorylation of ATF-2 by ERK1/2 is a critical mechanism for VEGF-A-driven VCAM-1 expression.
• This study reveals a novel paradigm for how growth factor isoforms dictate cellular outcomes via modulated signal transduction.