Abstract 481: NADPH Oxidase-Sensitive and -Insensitive Components of VEGF Signaling Pathways
Background: Vascular endothelial growth factor (VEGF) and reactive oxygen species (ROS) play critical roles in vascular physiology and pathophysiology. We have previously demonstrated that NADPH oxidase-derived ROS are required for VEGF-mediated migration and proliferation of endothelial cells. The goal of the present study was to determine the extent to which VEGF signaling is coupled to NADPH oxidase activity.
Methods and Results: Human coronary artery endothelial cells (HCAEC) were transfected with siRNA against the p47phox subunit of NADPH oxidase, treated in the absence or presence of VEGF, and assayed for signaling, gene expression and function. We show that NADPH oxidase activity is required for VEGF activation of PI3K-Akt-forkhead, PKC-IκB-NF-κB, and p38 MAPK, but not ERK1/2 or JNK. DNA microarrays reveal the existence of two distinct classes of VEGF responsive genes, one that is ROS-dependent and another that is independent of ROS levels. VEGF-induced, thrombomodulin-dependent activation of protein C is dependent on NADPH oxidase activity, whereas VEGF-induced decay accelerating factor-mediated protection of ECs against complement-mediated lysis is not.
Conclusions: These data suggest that NADPH oxidase activity plays a critical role in EC by differentially modulating VEGF signaling pathways and that this role may be leveraged to modify selective biological functions within the endothelium.