The deubiquitinase USP11 is a versatile and conserved regulator of autophagy

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.

USP11 promotes autophagy to attenuate LPS-induced oxidative stress in lung epithelial cells by stabilizing FOXO1 levels

BACKGROUND

Acute lung injury (ALI) is a critical condition characterized by severe inflammation and oxidative stress, leading to high morbidity and mortality. Despite advances in understanding ALI pathophysiology, effective treatment options remain limited. The increasing global burden of ALI, driven by factors such as infections, trauma, and environmental pollutants, emphasizes the urgent need for new therapeutic strategies. This study investigates the role of ubiquitin-specific protease 11 (USP11) in modulating Forkhead box protein O1 (FOXO1) to promote autophagy and alleviate oxidative stress in lung epithelial cells, which could provide novel insights into ALI therapeutic strategies.

MATERIALS AND METHODS

Bioinformatics were utilized to analyze the expression pattern of USP11 and FOXO1 in ALI, and their functions were detected based on gain- and loss-of function studies in vitro and in vivo. Besides, the effects of USP11 on FOXO1 stability and autophagy were examined through Western blot, immunofluorescence, and co-immunoprecipitation assays.

RESULTS

USP11 was found to be significantly downregulated in ALI, and its over-expression stabilized FOXO1, enhancing autophagy in lung epithelial cells. USP11 over-expression reduced oxidative stress and inflammatory cytokine production in vitro and in vivo. These results highlight the protective role of the USP11-FOXO1 axis in mitigating ALI pathophysiology.

CONCLUSIONS

This study identifies USP11 as a key regulator of FOXO1 and autophagy in ALI. The stabilization of FOXO1 through USP11 represents a promising therapeutic strategy for reducing oxidative stress and inflammation in ALI, warranting further clinical investigation.

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.

Targeting USP11 regulation by a novel lithium-organic coordination compound improves neuropathologies and cognitive functions in Alzheimer transgenic mice

Alzheimer's Disease (AD), as the most common neurodegenerative disease worldwide, severely impairs patients' cognitive functions. Although its exact etiology remains unclear, the abnormal aggregations of misfolded β-amyloid peptide and tau protein are considered pivotal in its pathological progression. Recent studies identify ubiquitin-specific protease 11 (USP11) as the key regulator of tau deubiquitination, exacerbating tau aggregation and AD pathology. Thereby, inhibiting USP11 function, via either blocking USP11 activity or lowering USP11 protein level, may serve as an effective therapeutic strategy against AD. Our research introduces IsoLiPro, a unique lithium isobutyrate-L-proline coordination compound, effectively lowers USP11 protein level and enhances tau ubiquitination in vitro. Additionally, long-term oral administration of IsoLiPro dramatically reduces total and phosphorylated tau levels in AD transgenic mice. Moreover, IsoLiPro also significantly lessens β-amyloid deposition and synaptic damage, improving cognitive functions in these animal models. These results indicate that IsoLiPro, as a novel small-molecule USP11 inhibitor, can effectively alleviate AD-like pathologies and improve cognitive functions, offering promise as a potential multi-targeting therapeutic agent against AD.

The role of ubiquitination in health and disease

Ubiquitination is an enzymatic process characterized by the covalent attachment of ubiquitin to target proteins, thereby modulating their degradation, transportation, and signal transduction. By precisely regulating protein quality and quantity, ubiquitination is essential for maintaining protein homeostasis, DNA repair, cell cycle regulation, and immune responses. Nevertheless, the diversity of ubiquitin enzymes and their extensive involvement in numerous biological processes contribute to the complexity and variety of diseases resulting from their dysregulation. The ubiquitination process relies on a sophisticated enzymatic system, ubiquitin domains, and ubiquitin receptors, which collectively impart versatility to the ubiquitination pathway. The widespread presence of ubiquitin highlights its potential to induce pathological conditions. Ubiquitinated proteins are predominantly degraded through the proteasomal system, which also plays a key role in regulating protein localization and transport, as well as involvement in inflammatory pathways. This review systematically delineates the roles of ubiquitination in maintaining protein homeostasis, DNA repair, genomic stability, cell cycle regulation, cellular proliferation, and immune and inflammatory responses. Furthermore, the mechanisms by which ubiquitination is implicated in various pathologies, alongside current modulators of ubiquitination are discussed. Enhancing our comprehension of ubiquitination aims to provide novel insights into diseases involving ubiquitination and to propose innovative therapeutic strategies for clinical conditions.

X-linked ubiquitin-specific peptidase 11 increases tauopathy vulnerability in women

Although women experience significantly higher tau burden and increased risk for Alzheimer's disease (AD) than men, the underlying mechanism for this vulnerability has not been explained. Here, we demonstrate through in vitro and in vivo models, as well as human AD brain tissue, that X-linked ubiquitin specific peptidase 11 (USP11) augments pathological tau aggregation via tau deubiquitination initiated at lysine-281. Removal of ubiquitin provides access for enzymatic tau acetylation at lysines 281 and 274. USP11 escapes complete X-inactivation, and female mice and people both exhibit higher USP11 levels than males. Genetic elimination of usp11 in a tauopathy mouse model preferentially protects females from acetylated tau accumulation, tau pathology, and cognitive impairment. USP11 levels also strongly associate positively with tau pathology in females but not males. Thus, inhibiting USP11-mediated tau deubiquitination may provide an effective therapeutic opportunity to protect women from increased vulnerability to AD and other tauopathies.