Abstract 21212: Novel Role of p90RSK-mediated Threonine 368 Phosphorylation of Sentrin/SUMO-Specific Proteases 2 on Disturbed Flow-induced Endothelial Dysfunction via Regulating p53-SUMOylation and Subsequent p53 Protein Stability
It is well known that endothelial cells (EC) dysfunction is exacerbated by disturbed flow (d-flow) and diabetes mellitus (DM). However, the mechanical insight of d-flow and DM in regulating vascular EC dysfunction remains largely unknown. We have performed the survey of the d-flow and DM-sensitive molecules in mice aorta, and found that p90RSK activation was significantly increased in d-flow area of apoE KO mice and streptozotocin (STZ)-induced DM mice in en face preparations. Interestingly, deactivation of p90RSK inhibited p53-SUMOylation, which leads to p53 nuclear export and p53-bcl2 binding as well as subsequent p53 protein stability by using synthesized inhibitor FMK and small interfering (si)RNA and adenovirus containing dominant negative form of p90RSK. In addition, p90RSK-mediated these signaling pathway was critical for EC apoptosis (5.79 ±0.5 fold increase compared with control; p<0.01). Therefore, we hypothesized that p90RSK-mediated p53-SUMOylation and subsequent p53-bcl2 binding contributes to EC dysfuction via apoptosis by d-flow and DM. Next, we found that p90RSK inhibits de-SUMOylation activity of Sentrin/SUMO-specific proteases 2 (SENP2) against p53. Mass spectrometry analysis showed p90RSK phosphorylates T368 of SENP2, and SENP2 mutant for T368 (T368A) failed to p90RSK-mediated p53-SUMOylation as well as p53-bcl2 binding, suggesting the key role of p90RSK on SENP2 de-SUMOylation activity via phosphorylation. To determine the role of p90RSK activation on EC dysfunction in vivo, EC-specific p90RSK transgenic mice (EC-p90RSK-Tg) were generated by crossing the p90RSK-Tg mouse to the mouse expressing tamoxifen-inducible Cre-recombinase CreERT2 under the regulation of the vascular EC cadherin promoter. Here, we found that leukocyte rolling was significantly accelerated in EC-p90RSK-Tg in mesenteric artery using intravital microscope (leukocyte velocity of EC-p90RSK-Tg: 2.1±0.26 fold decrease compared with WT; p<0.01). These data suggest the critical role of p90RSK-SENP2 module on d-flow and DM-mediated EC dysfunction.
- © 2010 by American Heart Association, Inc.