Small ubiquitin-like modifiers inhibitors lower blood pressure <i>via</i> ERK5/KLF2-dependent upregulation of the eNOS/NO pathway

Abstract Background Small ubiquitin-like modifiers (SUMO)ylation is a dynamic and reversible post-translational modification playing pivotal roles in the regulation of cancer, diabetes, heart failure, and neurological diseases. However, whether SUMO inhibitors also have anti-hypertension effect remains yet to be explored. Methods Blood pressure was monitored in spontaneously hypertensive rats (SHR) after Tannic acid (TA) administration for 4 weeks. The contents of nitric oxide (NO) and endothelin-1 (ET-1) in the serum of SHR were measured. Isolated endothelium-intact mesenteric artery rings were used to study relaxation effect of SUMO inhibitors. ERK5 SUMOylation was determined using coimmunoprecipitation (co-IP) and immunofluorescence (IF). NO levels were analyzed by IF. The expression levels of KLF2 and p-eNOS were semiquantified by Western blot analysis. The transcriptional activity of eNOS promotor was assayed using ChIP-PCR. Results Three SUMO inhibitors all reduced the phenylephrine (PE)-induced contraction of mesenteric artery rings in a concentration-dependent manner. Co-IP revealed that ponatinib promoted ERK5 SUMOylation, which was nulled following pretreatment with the SUMO inhibitors. IF displayed that TA increased ERK5 accumulation and its co-localization with SUMO-1 in the nucleus. ChIP-PCR unveiled TA-induced enhancement of KLF2-dependent eNOS promoter activity and upregulation of eNOS/NO expression in HUVECs. In vivo , TA significantly lowered the blood pressure and improved the vascular reactivity by activating the KLF2/eNOS/NO pathway. Additionally, the level of NO was elevated along with decreased ET-1 levels in the serum of SHR. Conclusions SUMO inhibitors inhibit ERK5 SUMOylation to promote KLF2-eNOS/NO signaling, indicating their therapeutic potential for the treatment of hypertension.