De-SUMOylation Enzyme of Sentrin/SUMO-Specific Protease 2 Regulates Disturbed Flow–Induced SUMOylation of ERK5 and p53 that Leads to Endothelial Dysfunction and Atherosclerosis

Abstract

Rationale Disturbed flow induces pro-inflammatory and apoptotic responses in endothelial cells (ECs), causing them to become dysfunctional and subsequently pro-atherogenic. Objective Although a possible link between SUMOylation of p53 and ERK5 detected during endothelial apoptosis and inflammation has been suggested, the mechanistic insights, especially under the pro-atherogenic flow condition, remain largely unknown. Methods and Results SUMOylation of p53 and ERK5 was induced by disturbed flow but not by steady laminar flow. To examine the role of the disturbed flow-induced p53 and ERK5 SUMOylation, we utilized de-SUMOylation enzyme of sentrin/SUMO-specific protease 2 deficiency (Senp2+/−) mice and observed a significant increase in endothelial apoptosis and adhesion molecule expression both in vitro and in vivo. These increases, however, were significantly inhibited in ECs overexpressing p53 and ERK5 SUMOylation site mutants. Senp2+/− mice exhibited increased leukocyte rolling along the endothelium, and accelerated formation of atherosclerotic lesions was observed in Senp2+/−/Ldlr−/−, but not Senp2+/+/Ldlr−/−, mice fed a high cholesterol diet. Notably, the extent of lesion size in the aortic arch of Senp2+/−/Ldlr−/− mice was much larger than that in the descending aorta, also suggesting a crucial role of the disturbed flow-induced SUMOylation of proteins including p53 and ERK5 in atherosclerosis formation. Conclusions These data show the unique role of SENP2 on endothelial function under disturbed flow and suggest that SUMOylation of p53 and ERK5 by disturbed flow contributes to the atherosclerotic plaque formation. Molecules involved in this newly discovered signaling will be useful targets for controlling ECs dysfunction and consequently atherosclerosis formation.

Disturbed flow-activated p90RSK kinase accelerates atherosclerosis by inhibiting SENP2 function

“…Previously, we found that d-flow induced SUMOylation of p53 (3) and ERK5 (12), leading to EC apoptosis and inflammation, respectively. Reduced expression of sentrin/SUMO-specific protease 2 (SENP2) increased p53 and ERK5 SUMOylation, hence accelerating EC dysfunction, inflammation, and consequently, atherosclerotic plaque formation in mice (11). Although these results might suggest SENP2 expression being downregulated by d-flow, we failed to detect such a change in ECs exposed to d-flow in vitro (11).…”

“…Because we have reported that d-flow SUMOylates p53 and ERK5 (11) and because both Ad-DN-p90RSK and a specific p90RSK kinase inhibitor, FMK-MEA, completely inhibit d-flowinduced p90RSK activation (refs. 13, 14, and Supplemental Figure 2B), p90RSK may play a role in p53 and ERK5 SUMOylation by Disturbed blood flow (d-flow) causes endothelial cell (EC) dysfunction, leading to atherosclerotic plaque formation.…”

“…To determine the role of SENP2 nuclear export and T368 phosphorylation in vivo, we investigated T368 phosphorylation-dependent SENP2 localization using en face aorta preparations and confocal microscopy ( Figure 6, B and C). We focused on 2 areas: the region exposed to d-flow (lesser curvature of the aortic arch) and the area exposed to s-flow (greater curvature of the aortic arch), as we described previously (11,16). When the endothelium was double-stained with anti-SENP2 or anti-phospho-SENP2-T368 together with anti-vascular endothelial-cadherin (anti-VE-Cad) as an EC marker, clear SENP2 nuclear localization was observed in the s-flow area.…”

“…SUMOylation plays an important role in regulating actin filament remodeling (6), migration (6,7), inflammation (8), and apoptosis (3) that occur in ECs in response to flow stimulation (3,4,8). SUMOylation is one of the most dynamic posttranslational modifications, with its diverse repertoire of effects, such as the localization, transcriptional activity, and DNA binding of modified proteins (9)(10)(11). Previously, we found that d-flow induced SUMOylation of p53 (3) and ERK5 (12), leading to EC apoptosis and inflammation, respectively.…”

“…Reduced expression of sentrin/SUMO-specific protease 2 (SENP2) increased p53 and ERK5 SUMOylation, hence accelerating EC dysfunction, inflammation, and consequently, atherosclerotic plaque formation in mice (11). Although these results might suggest SENP2 expression being downregulated by d-flow, we failed to detect such a change in ECs exposed to d-flow in vitro (11). Because p90RSK activation was associated with EC inflammation and apoptosis, we examined the role of p90RSK in regulating SUMOylation states of SENP2 substrates.…”