Abstract 19000: Shear Stress Responsive PKCe Modulates Mitochondrial Redox State With an Implication in Vascular Repair
Pulsatile (PSS) versus oscillatory (OSS) shear stress differentially modulates mechano-signal transduction with implications in atheroprotection and atherogenesis. In response to ischemia and reperfusion injury, Protein Kinase C isoform epsilon (PKCε) signaling in mitochondria confers cardioprotection. It is unknown whether PKCε was shear stress responsive via endothelial growth factor receptor (VEGFR) signaling with an implication in vascular endothelial repair. Both PSS (time-averaged shear stress (τave) = 25 dyne/cm2 at 1 Hz for 4 hr) and OSS (τave= 0.1±3 dyne/cm2 at 1 Hz for 4 hr) up-regulated PKCε mRNA by 1.7±0.2-fold and 1.5±0.1-fold in human aortic endothelial cells (HAEC), respectively, and protein expression by 1.5±0.1-fold and by 1.4±0.1-fold, respectively, which were inhibited in the presence of VEGFR-inhibitor, Cediranib (p < 0.05, n=4). Treatment with VEGF (100ng/ml) further up-regulated PKCε mRNA expression by 2.3±0.2-fold at 1 hour (p < 0.01, n=3). Matrigel assays revealed that both PKCε siRNA knockdown and VEGFR inhibitor disrupted endothelial tube formation in terms of reduction in tube lengths by 3.0±0.2-fold and by 3.8±0.2-fold, respectively, whereas over-expression of PKCε via adenovirus transfection rescued the formation in the presence and absence of VEGF inhibitor (p < 0.02, n=3). Furthermore, H2O2 increased MitoSox intensity for mitochondrial O2.- production (mtO2.-) by 1.4±0.2-fold, which was significantly attenuated by Adv-PKCε over-expression (p < 0.01, n=3). H2O2-induced mtO2.- production further disrupted tube formation, which was restored in the presence of Adv-PKCε over-expression. The phenotypic effect of PKCε was further recapitulated in the Tg(fli1:EGFP) transgenic zebrafish model, in which treatment with morpholinos to block either splicing or translation were used to inhibit PKCε protein expression, which interrupted repair of intersegmental vessels (ISV) after 3 days post tail amputation (n=6). Thus, our findings suggest that PKCε was shear stress responsive via endothelial growth factor receptor (VEGFR) signaling with an implication in vascular endothelial repair.
- © 2013 by American Heart Association, Inc.