Hypertension, mainly manifested as a sustained increase in arterial blood pressure (BP), is the most common preventable risk factor for cardiovascular diseases (CVDs), and is involved in mediating pathophysiological changes in cardiac insufficiency, stroke, atrial fibrillation, diabetes mellitus and other diseases, becoming one of the leading causes of mortality worldwide(Roth et al., 2017). Actually, BP increases with aging in most countries, and over 70% of the aged (more than 60-year-old) suffer from hypertension, compared to only 30% of the adults (40~59-year-old)(Buford, 2016). Although much attention has been paid to studying hypertension in recent decades, the precise mechanism of hypertension is still not fully understood. Angiotensin II (AngII), a downstream active peptide of the renin angiotensin system (RAS), is recognized as a crucial mediator of hypertension and vascular endothelial dysfunction(Forrester et al., 2018). Endothelial dysfunction is a common problem caused by hypertension and is considered as a precursor to the impaired microcirculation(Silva et al., 2016). Therefore, elucidating the mechanisms whereby AngII-induced pathological progression of hypertension is of considerable interest.

Murine double minute 2 (MDM2), an E3 ubiquitin ligase, participates in multiple cellular processes through modulating the stability of substrate molecular proteins, thereby influencing disease development(Matsushima et al., 2011; Poyurovsky et al., 2007). Although MDM2 is regarded outstanding in tumorigenesis by specifically ubiquitinating p53 and inducing p53 protein degradation, its diverse biological activities in many chronic diseases such as autoimmune and inflammation diseases, obesity, diabetes, and neurodegenerative diseases are also extensively investigated in recent years(Oliner et al., 2016; Wang et al., 2020). Dysregulated MDM2 is also implicated in cardiovascular impairment(Lam and Roudier, 2019). For instance, MDM2 is overexpressed in human atherosclerotic lesions, and MDM2 inhibitor JNJ-165 can alleviate the development of atherosclerosis via reversing mitochondrial damage and related inflammation in this process (Ihling et al., 1998, Zeng et al., 2022). MDM2 strengthens vascular calcification by mediating ubiquitination and degradation of histone deacetylase 1(Kwon et al., 2016). In addition, MDM2 is upregulated in patients with idiopathic pulmonary arterial hypertension, and MDM2 is partly responsible for the development of pulmonary arterial hypertension via mediating ubiquitination of angiotensin-converting enzyme 2(Shen et al., 2020). Meanwhile, treatment with the small molecule MDM2 antagonist nutlin-3 reduced the intima area and the intimal/media area ratio after vascular injury by suppressing the proliferation of vascular smooth muscle cells and endothelial cells and lowering the level of inflammation(Hashimoto et al., 2011). In particular, an aberrantly high expression of MDM2 in peripheral blood of middle-aged and elderly patients with hypertension was identified in Gene Expression Omnibus (GEO) dataset GSE24752 (http://www.ncbi.nlm.nih.gov/geo/), further verifying the involvement of MDM2 in hypertension, especially in the aged. However, the molecular basis underlying the regulatory role of MDM2 in AngII-induced pathological progression of hypertension remains elusive.

Interaction between Notch receptors (Notch1-4) and ligands (Jagged or Delta-like ligands (DLL)) triggers the signal transduction in Notch system, followed by the release of Notch intracellular domain (NICD) and its translocation into the nucleus. Currently, Notch signaling has been implicated in vascular homeostasis, development and injury response(Iso et al., 2003). The existing evidence confirms that Notch1 is an essential downstream pathway of MDM2 in mediating multiple pathological processes(Lei et al., 2017; Tang et al., 2017). Furthermore, it is identified that Notch1 serves as a novel activator for nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome which is a cytosolic complex for early inflammatory responses and closely involved in the pathogenesis of hypertension and endothelial dysfunction (Bai et al., 2020, Sun et al., 2017, Yan et al., 2019). Although these studies have indicated the potential interactions among MDM2, Notch1 signaling and NLRP3 inflammasome, it remains largely unknown whether MDM2 could regulate Notch1/NLRP3 inflammasome to participate in the development of hypertension.

In this study, we aimed to explore the role of MDM2 in AngII-induced hypertension and attempted to elucidate the potential mechanism underlying MDM2-associated endothelial dysfunction in hypertension, providing a potential target for novel antihypertensive drugs.