Deficiency of the Deubiquitinase UCHL1 Attenuates Pulmonary Arterial Hypertension

Mechanisms underlying altered ubiquitin-proteasome system activity during heart failure and pharmacological interventions

Heart failure (HF) is a refractory disease with a global prevalence that is continuously increasing. The mechanisms underlying the pathogenesis of HF are multi-faceted, intricate, and not yet fully elucidated. Appropriate levels of protein turnover are essential for maintaining cardiac homeostasis and, accordingly, compromised protein degradation systems can significantly contribute to heart disease. The ubiquitin-proteasome system (UPS) modulates the structure and function of cardiac cells by facilitating the degradation of signaling and structural proteins. Research in the preceding decade has focused on elucidating the role of the UPS in the context of cardiovascular physiology and pathophysiology. A comprehensive understanding of the UPS status and the underlying mechanisms contributing to its potential dysregulation in HF is imperative for developing targeted therapeutic interventions. Previous research has identified several novel interventions involving components of the UPS and several have been adapted for HF therapy. In this review, we summarize the mechanisms underlying altered UPS activity in HF and provide an outline of UPS regulators that affect the progression of HF. Additionally, the potential for small molecules to intervene in UPS function in HF is discussed.

Scutellarein ameliorates pulmonary arterial hypertension via sirtuin 1 mediated deacetylation of nicotinamide nucleotide transhydrogenase

Scutellarein (Sc), a natural flavonoid, holds potential for treating pulmonary arterial hypertension (PAH), yet its mechanisms remain unexplored. This study investigated Sc's therapeutic effects and underlying pathways in PAH. In vivo experiments demonstrated that Sc significantly attenuated right ventricular hypertension, pulmonary arterial remodeling, αSMA expression, and vascular inflammation in PAH models. In vitro, Sc suppressed hypoxia-induced proliferation, migration, inflammation, and pyroptosis in human pulmonary artery smooth muscle cells (HPASMCs). Mechanistically, Sc activated the SIRT1/NAD+ axis to restore mitochondrial homeostasis: it upregulated SIRT1 expression and elevated NAD+ levels by promoting SIRT1-mediated deacetylation of nicotinamide nucleotide transhydrogenase (NNT), thereby enhancing NNT activity. Elevated NAD+ further activated SIRT1, forming a self-reinforcing SIRT1/NNT/NAD+ feedback loop that mitigated hypoxia-induced mitochondrial dysfunction. This study identifies Sc as a novel regulator of the SIRT1-dependent NNT deacetylation pathway, which stabilizes NAD+ homeostasis to counteract HPASMCs dysregulation in PAH. These findings highlight Sc's potential as a therapeutic candidate for PAH, offering insights into targeting mitochondrial-metabolic pathways for vascular remodeling diseases.

Endothelial USP11 drives VEGFR2 signaling and angiogenesis via PRDX2/c-MYC axis

Angiogenesis is a crucial component of various physiological and pathological processes, including embryonic development, ischemic diseases, and tumor progression. Recent studies have highlighted the importance of ubiquitinases in angiogenesis. In this study, we utilized RNA sequencing data of the mouse retinal development model from the GEO database to identify the potential proangiogenic deubiquitinases and found USP11 was significantly upregulated. Although USP11 is known to regulate cell survival, DNA repair, and oxidative stress in cancers and ischemic conditions, its direct role in endothelial angiogenesis remains poorly understood. Here, we demonstrated that USP11 expression correlates with key pro-angiogenic genes and is significantly upregulated at both mRNA and protein levels in VEGF-treated human umbilical vein endothelial cells (HUVECs). USP11 knockout markedly inhibited angiogenesis both in vivo and in vitro, whereas USP11 overexpression promoted angiogenesis. Mechanistically, USP11 binds to PRDX2, facilitating the removal of its K63-linked polyubiquitination, which promotes its translocation into the nucleus. This facilitates the concurrent nuclear translocation of c-MYC, a PRDX2 interactor, which subsequently enhances the transcription of KDR (encoding VEGFR2) and activates the VEGFR2 signaling pathway. Our findings suggest that USP11 promotes angiogenesis by upregulating VEGFR2 expression through the PRDX2/c-MYC pathway, indicating that USP11 could serve as a potential target for clinical interventions in angiogenesis-related diseases.

The role of lactate metabolism and lactylation in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a complex and progressive disease characterized by elevated pulmonary artery pressure and vascular remodeling. Recent studies have underscored the pivotal role of metabolic dysregulation and epigenetic modifications in the pathogenesis of PAH. Lactate, a byproduct of glycolysis, is now recognized as a key molecule that links cellular metabolism with activity regulation. Recent findings indicate that, in addition to altered glycolytic activity and dysregulated. Lactate homeostasis and lactylation-a novel epigenetic modification-also play a significant role in the development of PAH. This review synthesizes current knowledge regarding the relationship between altered glycolytic activity and PAH, with a particular focus on the cumulative effects of lactate in pulmonary vascular cells. Furthermore, lactylation, an emerging epigenetic modification, is discussed in the context of PAH. By elucidating the complex interplay between lactate metabolism and lactylation in PAH, this review aims to provide insights into potential therapeutic targets. Understanding these metabolic pathways may lead to innovative strategies for managing PAH and improving patient outcomes. Future research should focus on the underlying mechanisms through which lactylation influences the pathophysiology of PAH, thereby aiding in the development of targeted interventions.

USP11 Promotes Endothelial Apoptosis-Resistance in Pulmonary Arterial Hypertension by Deubiquitinating HINT3

Pulmonary arterial hypertension (PAH) is a progressive, lethal, and incurable disease of the pulmonary vasculature. A previous genome-wide association study (GWAS) with Affymetrix microarray analysis data exhibited elevated histidine triad nucleotide-binding protein 3 (HINT3) in the lung samples of PAH compared to control subjects (failed donors, FD) and the positive correlations of HINT3 with deubiquitinase USP11 and B-cell lymphoma 2 (BCL2). In this study, we aim to investigate the roles and interplay of USP11 and HINT3 in the apoptosis resistance of PAH. The levels of USP11 and HINT3 were increased in the lungs of idiopathic PAH (IPAH) patients and Hypoxia/Sugen-treated mice. USP11 and HINT3 interacted physically, as shown by co-immunoprecipitation (co-IP) assay in human pulmonary arterial endothelial cells (HPAECs). HINT3 was degraded by polyubiquitination, which was reversed by USP11. Furthermore, HINT3 interacted with the anti-apoptotic mediator, BCL2. Overexpression of USP11 increased BCL2 content, congruent to elevated lung tissue levels seen in IPAH patients and Hypoxia/Sugen-treated mice. Conversely, the knockdown of HINT3 function led to a depletion of BCL2. Thus, we conclude that USP11 stabilizes HINT3 activation, which contributes to endothelial apoptosis-resistance of pulmonary arterial endothelial cells in PAH. This can potentially be a novel therapeutic target for ubiquitination modulators for PAH.

Ubiquitin C-terminal hydrolase L1 is a regulator of tumor growth and metastasis in double-negative prostate cancer

Prostate cancer is the second leading cause of cancer-related deaths among men worldwide. With heavy androgen deprivation therapies, prostate cancer may shift to androgen receptor negative and neuroendocrine negative subtype of castration resistant prostate cancer, defined as double-negative prostate cancer. Double-negative prostate cancer is associated with poor prognosis and disease mortality. The molecular mechanisms underlying the emergence of double-negative prostate cancer remain poorly understood. Here, we demonstrate that Ubiquitin C-Terminal Hydrolase L1 (UCH-L1), is negatively correlated with androgen receptor levels in prostate cancer patients. UCH-L1 plays a functional role in tumorigenesis and metastasis in double-negative prostate cancer. Knock-down of UCH-L1 decreases double-negative prostate cancer colony formation in vitro and tumor growth in vivo. Moreover, decrease of UCH-L1 significantly delays cell migration in vitro and spontaneous metastasis and metastatic colonization in vivo. Proteomic analysis revealed that mTORC1 signaling, androgen response signaling and MYC targets are the top three decreased pathways upon UCH-L1 decrease. Further, treatment with LDN-57444, a UCH-L1 small molecule inhibitor, impairs double-negative prostate cancer cell colony formation, migration in vitro, and metastatic colonization in vivo. Our study reveals that UCH-L1 is an important regulator of double-negative prostate cancer tumor growth and progression, providing a promising therapeutic target for this subtype of metastatic prostate cancer.

Ubiquitination of angiotensin-converting enzyme 2 contributes to the development of pulmonary arterial hypertension mediated by neural precursor cell-expressed developmentally down-regulated gene 4-Like

OBJECTIVES

In this study, we investigated whether neural precursor cell-expressed developmentally down-regulated gene 4-like (NEDD4L) is the E3 enzyme of angiotensin-converting enzyme 2 (ACE2) and whether NEDD4L degrades ACE2 via ubiquitination, leading to the progression of pulmonary arterial hypertension (PAH).

METHODS

Bioinformatic analyses were used to explore the E3 ligase that ubiquitinates ACE2. Cultured pulmonary arterial smooth muscle cells (PASMCs) and specimens from patients with PAH were used to investigate the crosstalk between NEDD4L and ACE2 and its ubiquitination in the context of PAH.

RESULTS

The inhibition of ubiquitination attenuated hypoxia-induced proliferation of PASMCs. The levels of NEDD4L were increased, and those of ACE2 were decreased in lung tissues from patients with PAH and in PASMCs. NEDD4L, the E3 ligase of ACE2, inhibited the expression of ACE2 in PASMCs, possibly through ubiquitination-mediated degradation. PAH was associated with upregulation of NEDD4L expression and downregulation of ACE2 expression.

CONCLUSIONS

NEDD4L, the E3 ubiquitination enzyme of ACE2, promotes the proliferation of PASMCs, ultimately leading to PAH.