Abstract 15846: Disturbed Flow-Induced P90RSK Activation Elicits Endothelial Dysfunction and Atherosclerosis Formation via Inhibiting De-Sumoylation Enzyme SENP2
Introduction: Disturbed flow (d-flow) but not steady laminar flow (s-flow) of blood flow elicits endothelial cell (EC) dysfunction, which lead to atherosclerosis formation. De-SUMOylation enzyme sentrin/SUMO-specific protease 2 (SENP2) regulates p53 and ERK5 function and protects EC from d-flow-mediated inflammation and apoptosis, but mechanisms for regulating SENP2 and EC dysfunction by d-flow are unknown.
Methods and Results: We found that d-flow, but not s-flow, increased both p53 and ERK5 SUMOylation through p90RSK activation. We investigated if p90RSK could associate and phosphorylate SENP2 and identified a p90RSK binding site (aa131-300) in SENP2 and a novel threonine phosphorylation site T368 in SENP2 using LC-MS/MS analyses. Inhibition of p90RSK/SENP2 interaction by an inhibitory fragment and T368A phospho-mutant significantly inhibited p90RSK-mediated p53 and ERK5 SUMOylation and inhibited d-flow-induced down-regulation of eNOS expression, up-regulation of adhesion molecule expression, and apoptosis in EC. Furthermore, we found a crucial role of SENP2-T368 phosphorylation in d-flow-mediated SENP2 nuclear export, leading to increased SUMOylation of nuclear p53 and ERK5. Significant increases in p90RSK activation, SENP2-T368 phosphorylation, and SENP2 nuclear export were also observed in the d-flow exposed area in the aortic arch in vivo. When mice overexpressing WT-p90rsk in an EC specific manner (WT-p90rsk-ETg) were crossed to Ldlr-/- mice, ECs inflammation, apoptosis, and atherosclerosis formation was enhanced. However, when the similar cross was made using mice overexpressing kinase dead mutant of p90rsk (DN-p90rsk-ETg), these processes were inhibited. Interestingly, deletion of Senp2 in the triple transgenic/knockout mice (DN-p90rsk-ETg/Senp2+/-/Ldlr-/-) abolished the protective effects observed in the DN-p90rsk-ETg/Ldlr-/- mice.
Conclusions: Collectively, these results demonstrate that p90RSK-mediated SENP2-T368 phosphorylation is critical for the d-flow-induced EC inflammation and apoptosis as well as atherosclerosis formation. Thus, SENP2-T368 phosphorylation is a pivotal switch providing d-flow-elicited p53 and ERK5 SUMOylation, leading to EC dysfunction and atherosclerosis formation.
- © 2013 by American Heart Association, Inc.