OTUD1 deubiquitinase regulates NF-κB- and KEAP1-mediated inflammatory responses and reactive oxygen species-associated cell death pathways

METTL3-mediated m6A modification of OTUD1 aggravates press overload induced myocardial hypertrophy by deubiquitinating PGAM5

Background: Pathological cardiac hypertrophy, a condition that contributes to heart failure, is characterized by its intricate pathogenesis. The meticulous regulation of protein function, localization, and degradation is a crucial role played by deubiquitinating enzymes in cardiac pathophysiology. This study clarifies the participation and molecular mechanism of OTUD1 (OTU Deubiquitinase 1) in pathological cardiac hypertrophy. Methods: We generated a cardiac-specific Otud1 knockout mouse line (Otud1-CKO) and adeno-associated virus serotype 9-Otud1 mice to determine the role of Otud1 in cardiac hypertrophy. Its impact on cardiomyocytes enlargement was investigated using the adenovirus. RNA immunoprecipitation was used to validate the specific m6a methyltransferase interacted with OTUD1 transcript. RNA sequencing in conjunction with immunoprecipitation-mass spectrometry analysis was employed to identify the direct targets of OTUD1. A series of depletion mutant plasmids were constructed to detect the interaction domain of OTUD1 and its targets. Results: Ang II-stimulated neonatal rat cardiac myocytes and mice hearts subjected to transverse aortic constriction (TAC) showed increased protein levels of Otud1. Cardiac hypertrophy and dysfunction were less frequent in Otud1-CKO mice during TAC treatment, while Otud1 overexpression worsened cardiac hypertrophy and remodeling. METTL3 mediated m6A modification of OTUD1 transcript promoted mRNA stability and elevated protein expression. In terms of pathogenesis, Otud1 plays a crucial role in cardiac hypertrophy by targeting Pgam5, leading to the robust activation of the Ask1-p38/JNK signal pathway to accelerate cardiac hypertrophy. Significantly, the pro-hypertrophy effects of Otud1 overexpression were largely eliminated when Ask1 knockdown. Conclusion: Our findings confirm that targeting the OTUD1-PGAM5 axis holds significant potential as a therapeutic approach for heart failure associated with pathological hypertrophy.

The plant extract PNS mitigates atherosclerosis via promoting Nrf2-mediated inhibition of ferroptosis through reducing USP2-mediated Keap1 deubiquitination

BACKGROUND AND PURPOSE

Atherosclerosis is the basis of cardiovascular disease. Ferroptosis is a form of programmed cell death characterized by lipid peroxidation, which contributes to atherogenesis. The plant extract PNS (Panax notoginseng saponins), containing the main active ingredients of Panax notoginseng, exhibits anti-atherogenic properties. Herein, we determined whether PNS and its major components could attenuate atherosclerosis by suppressing ferroptosis and revealed the underlying mechanism(s).

EXPERIMENTAL APPROACH

The anti-atherogenic effects of PNS and their association with inhibition of ferroptosis was determined in apoE-/- mice. In vitro, the anti-ferroptotic effect and mechanism(s) of PNS components were demonstrated in the presence of ferroptosis inducers. Expression of ferroptosis markers and the ubiquitination of Keap1 were evaluated in USP2-/- macrophages. Finally, the anti-atherogenic effect of USP2 knockout was determined by using USP2-/- mice treated with high-fat diet (HFD) and AAV-PCSK9.

KEY RESULTS

PNS inhibited ferroptosis and atherosclerosis in vivo. PNS suppressed ferroptosis and ferroptosis-aggravated foam cell formation and inflammation in vitro. Mechanistically, PNS and its components activated Nrf2 by antagonizing Keap1, which was attributed to the inhibition of USP2 expression. USP2 knockout antagonized ferroptosis and ferroptosis-aggravated foam cell formation and inflammation, thus mitigating atherosclerosis. USP2 knockout abolished inhibitory effects of PNS on foam cell formation and inflammation in vitro.

CONCLUSION AND IMPLICATIONS

PNS reduced USP2-mediated Keap1 de-ubiquitination and promoted Keap1 degradation, thereby activating Nrf2, improving iron metabolism and reducing lipid peroxidation, thus contributing to an anti-atherosclerotic outcome. Our study revealed the mechanism(s) underlying inhibition of ferroptosis and atherosclerosis by PNS.

The deubiquitinase OTUD1 stabilizes NRF2 to alleviate hepatic ischemia/reperfusion injury

Hepatic ischemia/reperfusion (I/R) injury is an important cause of liver function impairment following liver surgery. The ubiquitin-proteasome system (UPS) plays a crucial role in protein quality control and has substantial impact on the hepatic I/R process. Although OTU deubiquitinase 1 (OTUD1) is involved in diverse biological processes, its specific functional implications in hepatic I/R are not yet fully understood. This study demonstrates that OTUD1 alleviates oxidative stress, apoptosis, and inflammation induced by hepatic I/R injury. Mechanistically, OTUD1 deubiquitinates and activates nuclear factor erythroid 2-related factor 2 (NRF2) through its catalytic site cysteine 320 residue and ETGE motif, thereby attenuating hepatic I/R injury. Additionally, administration of a short peptide containing the ETGE motif significantly mitigates hepatic I/R injury in mice. Overall, our study elucidates the mechanism and role of OTUD1 in ameliorating hepatic I/R injury, providing a theoretical basis for potential treatment using ETGE-peptide.

The deubiquitinase OTUD1 deubiquitinates TIPE2 and plays a protective role in sepsis-induced lung injury by targeting TAK1-mediated MAPK and NF-κB signaling

Ovarian tumor domain-containing protease 1 (OTUD1) is a critical negative regulator that promotes innate immune homeostasis and is extensively involved in the pathogenesis of sepsis. In this study, we performed a powerful integration of multiomics analysis and an experimental mechanistic investigation to elucidate the immunoregulatory role of OTUD1 in sepsis at the clinical, animal and cellular levels. Our study revealed the upregulation of OTUD1 expression and the related distinctive alterations observed via multiomics profiling in clinical and experimental sepsis. Importantly, in vivo and in vitro, OTUD1 was shown to negatively regulate inflammatory responses and play a protective role in sepsis-induced pathological lung injury by mechanistically inhibiting the activation of the transforming growth factor-beta-activated kinase 1 (TAK1)-mediated mitogen-activated protein kinase (MAPK) and nuclear factor kappa-B (NF-κB) signaling pathways in the present study. Subsequently, we probed the molecular mechanisms underlying OTUD1's regulation of NF-κB and MAPK pathways by pinpointing the target proteins that OTUD1 can deubiquitinate. Drawing upon prior research conducted in our laboratory, it has been demonstrated that tumor necrosis factor-α-induced protein 8-like 2 (TIPE2) performs a protective function in septic lung injury and septic encephalopathy by suppressing the NF-κB and MAPK pathways. Hence, we hypothesized that TIPE2 might be a target protein of OTUD1. Additional experiments, including Co-IP, immunofluorescence co-localization, and Western blotting, revealed that OTUD1 indeed has the ability to deubiquitinate TIPE2. In summary, OTUD1 holds potential as an immunoregulatory and inflammatory checkpoint agent, and could serve as a promising therapeutic target for sepsis-induced lung injury.

Purinergic exposure induces epigenomic and transcriptomic-mediated preconditioning resembling epilepsy-associated microglial states

Microglia play a crucial role in a range of neuropathologies through exacerbated activation. Microglial inflammatory responses can be influenced by prior exposures to noxious stimuli, like increased levels of extracellular adenosine and ATP. These are characteristic of brain insults like epileptic seizures and could potentially shape subsequent responses through epigenetic regulation. We investigated DNA methylation and expression changes in human microglia-like cells differentiated from monocytes following ATP-mediated preconditioning. We demonstrate that microglia-like cells display homeostatic microglial features, shown by surface markers, transcriptome, and DNA methylome. After exposure to ATP, TLR-mediated activation leads to an exacerbated pro-inflammatory response. These changes are accompanied by methylation and transcriptional reprogramming associated with enhanced immune-related functions. The reprogramming associated with ATP-mediated preconditioning leads to profiles found in microglial subsets linked to epilepsy. Purine-driven microglia immune preconditioning drives epigenetic and transcriptional changes that could contribute to altered functions of microglia during seizure development and progression.

Small molecule inhibitors as adjuvants in cancer immunotherapy: enhancing efficacy and overcoming resistance

Adjuvant therapy is essential in cancer treatment to enhance primary treatment effectiveness, reduce adverse effects, and prevent recurrence. Small molecule inhibitors as adjuvants in cancer immunotherapy aim to harness their immunomodulatory properties to optimize treatment outcomes. By modulating the tumor microenvironment, enhancing immune cell function, and increasing tumor sensitivity to immunotherapy, small molecule inhibitors have the potential to improve patient responses. This review discusses the evolving use of small molecule inhibitors as adjuvants in cancer treatment, highlighting their role in enhancing the efficacy of immunotherapy and the opportunities for advancing cancer therapies in the future.

BECN1 regulates FADD/RIPK1/Caspase-8 complex formation via RIPK1 ubiquitination by downregulating OTUD1 in MI/R induced myocyte apoptosis

BACKGROUND

Cardiomyocyte apoptosis plays a vital role in myocardial ischemia-reperfusion (MI/R) injury; however, the role of beclin1 (BECN1) remains unclear. This study aimed at revealing the function of BECN1 during cardiomyocyte apoptosis after MI/R injury.

METHODS

In vivo, TTC and Evan's blue double staining was applied to verify the gross morphological alteration in both wild type (WT) mice and BECN1 transgene mice (BECN1-TG), and TUNEL staining and western blot were adopted to evaluate the cardiomyocyte apoptosis. In vitro, a hypoxia/reoxygenation (H/R) model was established in H9c2 cells to simulate MI/R injury. Proteomics analysis was preformed to verify if apoptosis occurs in the H/R cellular model. And apoptosis factors, RIPK1, Caspase-1, Caspase-3, and cleaved Caspase-3, were investigated using western bolting. In addition, the mRNA level were verified using RT-PCR. To further investigate the protein interactions small interfering RNA and lentiviral transfection were used. To continue investigate the protein interactions, immunofluorescence and coimmunoprecipitation were applied.

RESULTS

Morphologically, BECN1 significantly attenuated the apoptosis from TTC-Evan's staining, TUNEL, and cardiac tissue western blot. After H/R, a RIPK1-induced complex (complex II) containing RIPK1, Caspase-8, and FADD was formed. Thereafter, cleaved Caspase-3 was activated, and myocyte apoptosis occurred. However, BECN1 decreased the expression of RIPK1, Caspase-8, and FADD. Nevertheless, BECN1 overexpression increased RIPK1 ubiquitination before apoptosis by inhibiting OTUD1.

CONCLUSIONS

BECN1 regulates FADD/RIPK1/Caspase-8 complex formation via RIPK1 ubiquitination by downregulating OTUD1 in C-Caspase-3-induced myocyte apoptosis after MI/R injury. Therefore, BECN1 can function as a cardioprotective candidate.

Oxidative cell death in cancer: mechanisms and therapeutic opportunities

Reactive oxygen species (ROS) are highly reactive oxygen-containing molecules generated as natural byproducts during cellular processes, including metabolism. Under normal conditions, ROS play crucial roles in diverse cellular functions, including cell signaling and immune responses. However, a disturbance in the balance between ROS production and cellular antioxidant defenses can lead to an excessive ROS buildup, causing oxidative stress. This stress damages essential cellular components, including lipids, proteins, and DNA, potentially culminating in oxidative cell death. This form of cell death can take various forms, such as ferroptosis, apoptosis, necroptosis, pyroptosis, paraptosis, parthanatos, and oxeiptosis, each displaying distinct genetic, biochemical, and signaling characteristics. The investigation of oxidative cell death holds promise for the development of pharmacological agents that are used to prevent tumorigenesis or treat established cancer. Specifically, targeting key antioxidant proteins, such as SLC7A11, GCLC, GPX4, TXN, and TXNRD, represents an emerging approach for inducing oxidative cell death in cancer cells. This review provides a comprehensive summary of recent progress, opportunities, and challenges in targeting oxidative cell death for cancer therapy.

Macrophage OTUD1-CARD9 axis drives isoproterenol-induced inflammatory heart remodelling

BACKGROUND

Chronic inflammation contributes to the progression of isoproterenol (ISO)-induced heart failure (HF). Caspase-associated recruitment domain (CARD) families are crucial proteins for initiation of inflammation in innate immunity. Nonetheless, the relevance of CARDs in ISO-driven cardiac remodelling is little explored.

METHODS

This study utilized Card9-/- mice and reconstituted C57BL/6 mice with either Card9-/- or Otud1-/- marrow-derived cells. Mechanistic studies were conducted in primary macrophages, cardiomyocytes, fibroblasts and HEK-293T cells.

RESULTS

Here, we demonstrated that CARD9 was substantially upregulated in murine hearts infused with ISO. Either whole-body CARD9 knockout or myeloid-specific CARD9 deletion inhibited ISO-driven murine cardiac inflammation, remodelling and dysfunction. CARD9 deficiency in macrophages prevented ISO-induced inflammation and alleviated remodelling changes in cardiomyocytes and fibroblasts. Mechanistically, we found that ISO enhances the activity of CARD9 by upregulating ovarian tumour deubiquitinase 1 (OTUD1) in macrophages. We further demonstrated that OTUD1 directly binds to the CARD9 and then removes the K33-linked ubiquitin from CARD9 to promote the assembly of the CARD9-BCL10-MALT1 (CBM) complex, without affecting CARD9 stability. The ISO-activated CBM complex results in NF-κB activation and macrophage-based inflammatory gene overproduction, which then enhances cardiomyocyte hypertrophy and fibroblast fibrosis, respectively. Myeloid-specific OTUD1 deletion also attenuated ISO-induced murine cardiac inflammation and remodelling.

CONCLUSIONS

These results suggested that the OTUD1-CARD9 axis is a new pro-inflammatory signal in ISO-challenged macrophages and targeting this axis has a protective effect against ISO-induced HF.

KEY POINTS

Macrophage CARD9 was elevated in heart tissues of mice under chronic ISO administration. Either whole-body CARD9 knockout or myeloid-specific CARD9 deficiency protected mice from ISO-induced inflammatory heart remodeling. ISO promoted the assembly of CBM complex and then activated NF-κB signaling in macrophages through OTUD1-mediated deubiquitinating modification. OTUD1 deletion in myeloid cells protected hearts from ISO-induced injuries in mice.

OTUD1 Deficiency Alleviates LPS-Induced Acute Lung Injury in Mice by Reducing Inflammatory Response

The ovarian tumor (OTU) family consists of deubiquitinating enzymes thought to play a crucial role in immunity. Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) pose substantial clinical challenges due to severe respiratory complications and high mortality resulting from uncontrolled inflammation. Despite this, no study has explored the potential link between the OTU family and ALI/ARDS. Using publicly available high-throughput data, 14 OTUs were screened in a simulating bacteria- or LPS-induced ALI model. Subsequently, gene knockout mice and transcriptome sequencing were employed to explore the roles and mechanisms of the selected OTUs in ALI. Our screen identified OTUD1 in the OTU family as a deubiquitinase highly related to ALI. In the LPS-induced ALI model, deficiency of OTUD1 significantly ameliorated pulmonary edema, reduced permeability damage, and decreased lung immunocyte infiltration. Furthermore, RNA-seq analysis revealed that OTUD1 deficiency inhibited key pathways, including the IFN-γ/STAT1 and TNF-α/NF-κB axes, ultimately mitigating the severity of immune responses in ALI. In summary, our study highlights OTUD1 as a critical immunomodulatory factor in acute inflammation. These findings suggest that targeting OTUD1 could hold promise for the development of novel treatments against ALI/ARDS.

Therapeutic strategies of targeting non-apoptotic regulated cell death (RCD) with small-molecule compounds in cancer

Regulated cell death (RCD) is a controlled form of cell death orchestrated by one or more cascading signaling pathways, making it amenable to pharmacological intervention. RCD subroutines can be categorized as apoptotic or non-apoptotic and play essential roles in maintaining homeostasis, facilitating development, and modulating immunity. Accumulating evidence has recently revealed that RCD evasion is frequently the primary cause of tumor survival. Several non-apoptotic RCD subroutines have garnered attention as promising cancer therapies due to their ability to induce tumor regression and prevent relapse, comparable to apoptosis. Moreover, they offer potential solutions for overcoming the acquired resistance of tumors toward apoptotic drugs. With an increasing understanding of the underlying mechanisms governing these non-apoptotic RCD subroutines, a growing number of small-molecule compounds targeting single or multiple pathways have been discovered, providing novel strategies for current cancer therapy. In this review, we comprehensively summarized the current regulatory mechanisms of the emerging non-apoptotic RCD subroutines, mainly including autophagy-dependent cell death, ferroptosis, cuproptosis, disulfidptosis, necroptosis, pyroptosis, alkaliptosis, oxeiptosis, parthanatos, mitochondrial permeability transition (MPT)-driven necrosis, entotic cell death, NETotic cell death, lysosome-dependent cell death, and immunogenic cell death (ICD). Furthermore, we focused on discussing the pharmacological regulatory mechanisms of related small-molecule compounds. In brief, these insightful findings may provide valuable guidance for investigating individual or collaborative targeting approaches towards different RCD subroutines, ultimately driving the discovery of novel small-molecule compounds that target RCD and significantly enhance future cancer therapeutics.

Mini-review: research and progress of oxeiptosis in diseases

Oxeiptosis is a novel cell death pathway that was introduced in 2018. As a form of regulated cell death, it operates independently of caspases and is induced by ROS. Distinguished from other cell death pathways such as apoptosis, necroptosis, pyroptosis, and ferroptosis, oxeiptosis features unique damage causes pivotal genes, and signaling pathways (KEAP1/PGAM5/AIFM1). Emerging studies indicate that oxeiptosis plays a significant role in the progression of various diseases and its regulation could serve as a promising therapeutic target. However, the precise molecular mechanisms underlying oxeiptosis remain to be fully elucidated. In this mini-review, we systematically summarize the latest developments in oxeiptosis-related diseases while detailing the molecular mechanisms and regulatory networks of oxeiptosis. These insights offer a foundation for a deeper understanding of oxeiptosis.

Disease activity drives divergent epigenetic and transcriptomic reprogramming of monocyte subpopulations in systemic lupus erythematosus

OBJECTIVES

Systemic lupus erythematosus (SLE) is characterised by systemic inflammation involving various immune cell types. Monocytes, pivotal in promoting and regulating inflammation in SLE, differentiate from classic monocytes into intermediate and non-classic monocytes, assuming diverse roles and changing their proportions in inflammation. In this study, we investigated the epigenetic and transcriptomic profiles of these and novel monocyte subsets in SLE in relation to activity and progression.

METHODS

We obtained the DNA methylomes and transcriptomes of classic, intermediate, non-classic monocytes in patients with SLE (at first and follow-up visits) and healthy donors. We integrated these data with single-cell transcriptomics of SLE and healthy donors and interrogated their relationships with activity and progression.

RESULTS

In addition to shared DNA methylation and transcriptomic alterations associated with a strong interferon signature, we identified monocyte subset-specific alterations, especially in DNA methylation, which reflect an impact of SLE on monocyte differentiation. SLE classic monocytes exhibited a proinflammatory profile and were primed for macrophage differentiation. SLE non-classic monocytes displayed a T cell differentiation-related phenotype, with Th17-regulating features. Changes in monocyte proportions, DNA methylation and expression occurred in relation to disease activity and involved the STAT pathway. Integration of bulk with single-cell RNA sequencing datasets revealed disease activity-dependent expansion of SLE-specific monocyte subsets, further supported the interferon signature for classic monocytes, and associated intermediate and non-classic populations with exacerbated complement activation.

CONCLUSIONS

Disease activity in SLE drives a subversion of the epigenome and transcriptome programme in monocyte differentiation, impacting the function of different subsets and allowing to generate predictive methods for activity and progression.

NF-ĸB axis in diabetic neuropathy, cardiomyopathy and nephropathy: A roadmap from molecular intervention to therapeutic strategies

Diabetes mellitus (DM) is a metabolic illness defined by elevated blood glucose levels, mediating various tissue alterations, including the dysfunction of vital organs. Diabetes mellitus (DM) can lead to many consequences that specifically affect the brain, heart, and kidneys. These issues are known as neuropathy, cardiomyopathy, and nephropathy, respectively. Inflammation is acknowledged as a pivotal biological mechanism that contributes to the development of various diabetes consequences. NF-κB modulates inflammation and the immune system at the cellular level. Its abnormal regulation has been identified in several clinical situations, including cancer, inflammatory bowel illnesses, cardiovascular diseases, and Diabetes Mellitus (DM). The purpose of this review is to evaluate the potential impact of NF-κB on complications associated with DM. Enhanced NF-κB activity promotes inflammation, resulting in cellular harm and compromised organ performance. Phytochemicals, which are therapeutic molecules, can potentially decline the NF-κB level, therefore alleviating inflammation and the progression of problems correlated with DM. More importantly, the regulation of NF-κB can be influenced by various factors, such as TLR4 in DM. Highlighting these factors can facilitate the development of novel therapies in the future.

Pigeon novel-miR-741 targets OTUD1 to inhibit proliferation and promote apoptosis of crop fibroblasts

Trichomonas gallinae (T. gallinae) is a globally distributed protozoan parasite and could cause serious damage to the pigeon industry. MiRNAs have important roles in regulating parasite infection, but its impacts on T. gallinae resistance have rarely been reported. In the present study, we identified a new miRNA (novel-miR-741) and its predicted target OTU deubiquitinase 1 (OTUD1) that might be associated with immunity to T. gallinae in pigeon. Novel-miR-741 and OTUD1 over-expression vectors and interference vectors were constructed. Results from dual luciferase activity assay demonstrated that OTUD1 was a downstream target of novel-miR-741. The Cell Counting Kit-8 and apoptosis assays showed that novel-miR-741 inhibited the proliferation and promoted apoptosis of pigeon crop fibroblasts. Meanwhile, mRNA levels of OTUD1 were significantly reduced in novel-miR-741 mimic-transfected fibroblasts, while mRNA levels of OTUD1 were significantly increased in the novel-miR-741 inhibitor-transfected fibroblasts. The regulatory roles of si-OTUD1 on fibroblasts proliferation, apoptosis, and migration were similar to novel-miR-741 mimic. Our findings demonstrated that novel-miR-741 inhibited the proliferation, and migration of crop fibroblasts, while OTUD1 promoted the proliferation and migration of crop fibroblasts. Therefore, the regulation of OTUD1 by novel-miR-741 was proposed as a potential therapeutic strategy for T. gallinae.

OTUD1 promotes hypertensive kidney fibrosis and injury by deubiquitinating CDK9 in renal epithelial cells

Hypertensive renal disease (HRD) contributes to the progression of kidney dysfunction and ultimately leads to end-stage renal disease. Understanding the mechanisms underlying HRD is critical for the development of therapeutic strategies. Deubiquitinating enzymes (DUBs) have been recently highlighted in renal pathophysiology. In this study, we investigated the role of a DUB, OTU Domain-Containing Protein 1 (OTUD1), in HRD models. HRD was induced in wild-type or Otud1 knockout mice by chronic infusion of angiotensin II (Ang II, 1 μg/kg per min) through a micro-osmotic pump for 4 weeks. We found that OTUD1 expression levels were significantly elevated in the kidney tissues of Ang II-treated mice. Otud1 knockout significantly ameliorated Ang II-induced HRD, whereas OTUD1 overexpression exacerbated Ang II-induced kidney damage and fibrosis. Similar results were observed in TCMK-1 cells but not in SV40 MES-13 cells following Ang II (1 μM) treatment. In Ang II-challenged TCMK-1 cells, we demonstrated that OTUD1 bound to CDK9 and induced CDK9 deubiquitination: OTUD1 catalyzed K63 deubiquitination on CDK9 with its Cys320 playing a critical role, promoting CDK9 phosphorylation and activation to induce inflammatory responses and fibrosis in kidney epithelial cells. Administration of a CDK9 inhibitor NVP-2 significantly ameliorated Ang II-induced HRD in mice. This study demonstrates that OTUD1 mediates HRD by targeting CDK9 in kidney epithelial cells, suggesting OTUD1 is a potential target in treating this disease.

Inhibition of NF-κB signaling unveils novel strategies to overcome drug resistance in cancers

Drug resistance in cancer remains a major challenge in oncology, impeding the effectiveness of various treatment modalities. The nuclear factor-kappa B (NF-κB) signaling pathway has emerged as a critical player in the development of drug resistance in cancer cells. This comprehensive review explores the intricate relationship between NF-κB and drug resistance in cancer. We delve into the molecular mechanisms through which NF-κB activation contributes to resistance against chemotherapeutic agents, targeted therapies, and immunotherapies. Additionally, we discuss potential strategies to overcome this resistance by targeting NF-κB signaling, such as small molecule inhibitors and combination therapies. Understanding the multifaceted interactions between NF-κB and drug resistance is crucial for the development of more effective cancer treatment strategies. By dissecting the complex signaling network of NF-κB, we hope to shed light on novel therapeutic approaches that can enhance treatment outcomes, ultimately improving the prognosis for cancer patients. This review aims to provide a comprehensive overview of the current state of knowledge on NF-κB and its role in drug resistance, offering insights that may guide future research and therapeutic interventions in the fight against cancer.

OTUD1 promotes isoprenaline- and myocardial infarction-induced heart failure by targeting PDE5A in cardiomyocytes

Heart failure represents a major cause of death worldwide. Recent research has emphasized the potential role of protein ubiquitination/deubiquitination protein modification in cardiac pathology. Here, we investigate the role of the ovarian tumor deubiquitinase 1 (OTUD1) in isoprenaline (ISO)- and myocardial infarction (MI)-induced heart failure and its molecular mechanism. OTUD1 protein levels were raised markedly in murine cardiomyocytes after MI and ISO treatment. OTUD1 deficiency attenuated myocardial hypertrophy and cardiac dysfunction induced by ISO infusion or MI operation. In vitro, OTUD1 knockdown in neonatal rat ventricular myocytes (NRVMs) attenuated ISO-induced injuries, while OTUD1 overexpression aggravated the pathological changes. Mechanistically, LC-MS/MS and Co-IP studies showed that OTUD1 bound directly to the GAF1 and PDEase domains of PDE5A. OTUD1 was found to reverse K48 ubiquitin chain in PDE5A through cysteine at position 320 of OTUD1, preventing its proteasomal degradation. PDE5A could inactivates the cGMP-PKG-SERCA2a signaling axis which dysregulate the calcium handling in cardiomyocytes, and leading to the cardiomyocyte injuries. In conclusion, OTUD1 promotes heart failure by deubiquitinating and stabilizing PDE5A in cardiomyocytes. These findings have identified PDE5A as a new target of OTUD1 and emphasize the potential of OTUD1 as a target for treating heart failure.

Friend or foe? Reciprocal regulation between E3 ubiquitin ligases and deubiquitinases

Protein ubiquitination is a post-translational modification that entails the covalent attachment of the small protein ubiquitin (Ub), which acts as a signal to direct protein stability, localization, or interactions. The Ub code is written by a family of enzymes called E3 Ub ligases (∼600 members in humans), which can catalyze the transfer of either a single ubiquitin or the formation of a diverse array of polyubiquitin chains. This code can be edited or erased by a different set of enzymes termed deubiquitinases (DUBs; ∼100 members in humans). While enzymes from these distinct families have seemingly opposing activities, certain E3-DUB pairings can also synergize to regulate vital cellular processes like gene expression, autophagy, innate immunity, and cell proliferation. In this review, we highlight recent studies describing Ub ligase-DUB interactions and focus on their relationships.

Vialinin A alleviates oxidative stress and neuronal injuries after ischaemic stroke by accelerating Keap1 degradation through inhibiting USP4-mediated deubiquitination

BACKGROUND

Oxidative stress is known as a hallmark of cerebral ischaemia‒reperfusion injury and it exacerbates the pathologic progression of ischaemic brain damage. Vialinin A, derived from a Chinese edible mushroom, possesses multiple pharmacological activities in cancer, Kawasaki disease, asthma and pathological scarring. Notably, vialinin A is an inhibitor of ubiquitin-specific peptidase 4 (USP4) that shows anti-inflammatory and antioxidative properties. However, the precise effect of vialinin A in ischaemic stroke, as well as its underlying mechanisms, remains largely unexplored.

PURPOSE

The present research focuses on the impacts of vialinin A on oxidative stress and explores the underlying mechanisms involved while also examining its potentiality as a therapeutic candidate for ischaemic stroke.

METHODS

Mouse ischaemic stroke was conducted by MCAO surgery. Vialinin A was administered via lateral ventricular injection at a dose of 2 mg/kg after reperfusion. Subsequent experiments were meticulously conducted at the appropriate time points. Stroke outcomes were evaluated by TTC staining, neurological score, Nissl staining and behavioural analysis. Co-IP assays were operated to examine the protein-protein interactions. Immunoblot analysis, qRT-PCR, and luciferase reporter assays were conducted to further investigate its underlying mechanisms.

RESULTS

In this study, we initially showed that administration of vialinin A alleviated cerebral ischaemia‒reperfusion injury-induced neurological deficits and neuronal apoptosis. Furthermore, vialinin A, which is an antioxidant, reduced oxidative stress injury, promoted the activation of the Keap1-Nrf2-ARE signaling pathway and increased the protein degradation of Keap1. The substantial neuroprotective effects of vialinin A against ischaemic stroke were compromised by the overexpression of USP4. Mechanistically, vialinin A inhibited the deubiquitinating enzymatic activity of USP4, leading to enhanced ubiquitination of Keap1 and subsequently promoting its degradation. This cascade caused the activation of Nrf2-dependent antioxidant response, culminating in a reduction of neuronal apoptosis and the amelioration of neurological dysfunction following ischaemic stroke.

CONCLUSIONS

This study demonstrates that inhibition of USP4 to activate Keap1-Nrf2-ARE signaling pathway may represent a mechanism by which vialinin A conferred protection against cerebral ischaemia‒reperfusion injury and sheds light on its promising prospects as a therapeutic intervention for ischaemic stroke.

The role of neutrophil extracellular traps in sepsis and sepsis-related acute lung injury

Neutrophils release neutrophil extracellular traps (NETs) to trap pathogenic microorganisms. NETs are involved in the inflammatory response and bacterial killing and clearance. However, their excessive activation can lead to an inflammatory storm in the body, which may damage tissues and cause organ dysfunction. Organ dysfunction is the main pathophysiological cause of sepsis and also a cause of the high mortality rate in sepsis. Acute lung injury caused by sepsis accounts for the highest proportion of organ damage in sepsis. NET formation can lead to the development of sepsis because by promoting the release of interleukin-1 beta, interleukin-8, and tumor necrosis factor-alpha, thereby accelerating acute lung injury. In this review, we describe the critical role of NETs in sepsis-associated acute lung injury and review the current knowledge and novel therapeutic approaches.

Herpesvirus latent infection promotes stroke via activating the OTUD1/NF-κB signaling pathway

OBJECTIVE

Our study aimed to reveal the molecular mechanisms underlying the regulation of cerebral infarction by herpes virus latency infection via the OTUD1/NF-κB signaling pathway using evidence-based medicine Meta-analysis and bioinformatics analysis.

METHODS

We conducted a Meta-analysis by searching Pubmed, Embase, and Web of Science databases to evaluate the correlation between herpes virus infection and increased risk of cerebral infarction. We obtained wild-type or mutant herpes virus latent infection-related brain tissue datasets from the GEO database and performed differential analysis to identify differentially expressed genes (DEGs) in the brain tissue after herpes virus latent infection. We further conducted WGCNA co-expression analysis on the cerebral infarction-related datasets from the GEO database to obtain key module genes and intersect them with the DEGs. We used ROC curve analysis to identify the key gene OTUD1 for predicting the occurrence of cerebral infarction and combined correlation and pathway enrichment analyses to identify the downstream pathways regulated by OTUD1.

RESULTS

Our meta-analysis revealed that herpes virus infection is associated with an increased risk of cerebral infarction. By integrating the differential analysis and WGCNA co-expression analysis of GEO chip data, we identified three key genes mediating cerebral infarction after herpes virus latent infection. ROC curve analysis identified the key gene OTUD1, and the correlation and pathway enrichment analyses showed that OTUD1 regulates the NF-κB signaling pathway to mediate cerebral infarction.

CONCLUSION

Herpes virus latent infection promotes cerebral infarction by activating the OTUD1/NF-κB signaling pathway.

Development of an OTUD1 ubiquitin variant inhibitor

OTUD1 (Ovarian tumor domain-containing deubiquitinase 1) is a member of the OTU domain-containing deubiquitinase family of enzymes involved in immunoregulation and tumorigenesis pathways. OTUD1 consists of three distinct regions: an unstructured N-terminal region, an OTU-fold catalytic domain, and a ubiquitin-interacting motif (UIM) containing region. Enhanced enzymatic activity and a strong preference for K63-linked substrates are imparted by the UIM containing region. We used phage display with a ubiquitin variant (UbV) library to identify binders for OTUD1 lacking the unstructured N-terminal region (OTUD1OTU + UIM) in an attempt to identify inhibitors bridging the catalytic domain and the UIM containing region. Two UbVs were identified (UbVOD.1 and UbVOD.2) with high affinity and specificity for OTUD1. Of the UbVs identified, UbVOD.1 inhibited OTUD1 activity towards mono-Ub and K63-linked di-Ub substrates in vitro with single-digit nanomolar IC50 and potently inhibited deubiquitinase activity with poly-Ub chains of other linkages. In vivo expression of UbVOD.1 alone was unstable, however as a di-UbV, global deubiquitination and deubiquitinase activity with the OTUD1 substrate RIPK1 were inhibited. Herein we describe the development of molecular tools for exploring the activity of OTUD1 in a cellular context, towards protein-based therapeutics.

Mouse endothelial OTUD1 promotes angiotensin II-induced vascular remodeling by deubiquitinating SMAD3

Understanding the molecular mechanisms of pathological vascular remodeling is important for treating cardiovascular diseases and complications. Recent studies have highlighted a role of deubiquitinases in vascular pathophysiology. Here, we investigate the role of a deubiquitinase, OTUD1, in angiotensin II (Ang II)-induced vascular remodeling. We detect upregulated OTUD1 in the vascular endothelium of Ang II-challenged mice and show that OTUD1 deletion attenuates vascular remodeling, collagen deposition, and EndMT. Conversely, OTUD1 overexpression aggravates these pathological changes both in vivo and in vitro. Mechanistically, SMAD3 is identified as a substrate of OTUD1 using co-immunoprecipitation followed by LC-MS/MS. We find that OTUD1 stabilizes SMAD3 and facilitates SMAD3/SMAD4 complex formation and subsequent nuclear translocation through both K48- and K63-linked deubiquitination. OTUD1-mediated SMAD3 activation regulates transcription of genes involved in vascular EndMT and remodeling in HUVECs. Finally, SMAD3 inhibition reverses OTUD1-promoted vascular remodeling. Our findings demonstrate that endothelial OTUD1 promotes Ang II-induced vascular remodeling by deubiquitinating SMAD3. We identify SMAD3 as a target of OTUD1 and propose OTUD1 as a potential therapeutic target for diseases related to vascular remodeling.

Pleiotropic Roles of a KEAP1-Associated Deubiquitinase, OTUD1

Protein ubiquitination, which is catalyzed by ubiquitin-activating enzymes, ubiquitin-conjugating enzymes, and ubiquitin ligases, is a crucial post-translational modification to regulate numerous cellular functions in a spatio-temporal-specific manner. The human genome encodes ~100 deubiquitinating enzymes (DUBs), which antagonistically regulate the ubiquitin system. OTUD1, an ovarian tumor protease (OTU) family DUB, has an N-terminal-disordered alanine-, proline-, glycine-rich region (APGR), a catalytic OTU domain, and a ubiquitin-interacting motif (UIM). OTUD1 preferentially hydrolyzes lysine-63-linked ubiquitin chains in vitro; however, recent studies indicate that OTUD1 cleaves various ubiquitin linkages, and is involved in the regulation of multiple cellular functions. Thus, OTUD1 predominantly functions as a tumor suppressor by targeting p53, SMAD7, PTEN, AKT, IREB2, YAP, MCL1, and AIF. Furthermore, OTUD1 regulates antiviral signaling, innate and acquired immune responses, and cell death pathways. Similar to Nrf2, OTUD1 contains a KEAP1-binding ETGE motif in its APGR and regulates the reactive oxygen species (ROS)-mediated oxidative stress response and cell death. Importantly, in addition to its association with various cancers, including multiple myeloma, OTUD1 is involved in acute graft-versus-host disease and autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, and ulcerative colitis. Thus, OTUD1 is an important DUB as a therapeutic target for a variety of diseases.

Involvement of heterologous ubiquitination including linear ubiquitination in Alzheimer's disease and amyotrophic lateral sclerosis

In neurodegenerative diseases such as Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS), the progressive accumulation of ubiquitin-positive cytoplasmic inclusions leads to proteinopathy and neurodegeneration. Along with the seven types of Lys-linked ubiquitin chains, the linear ubiquitin chain assembly complex (LUBAC)-mediated Met1-linked linear ubiquitin chain, which activates the canonical NF-κB pathway, is also involved in cytoplasmic inclusions of tau in AD and TAR DNA-binding protein 43 in ALS. Post-translational modifications, including heterologous ubiquitination, affect proteasomal and autophagic degradation, inflammatory responses, and neurodegeneration. Single nucleotide polymorphisms (SNPs) in SHARPIN and RBCK1 (which encodes HOIL-1L), components of LUBAC, were recently identified as genetic risk factors of AD. A structural biological simulation suggested that most of the SHARPIN SNPs that cause an amino acid replacement affect the structure and function of SHARPIN. Thus, the aberrant LUBAC activity is related to AD. Protein ubiquitination and ubiquitin-binding proteins, such as ubiquilin 2 and NEMO, facilitate liquid-liquid phase separation (LLPS), and linear ubiquitination seems to promote efficient LLPS. Therefore, the development of therapeutic approaches that target ubiquitination, such as proteolysis-targeting chimeras (PROTACs) and inhibitors of ubiquitin ligases, including LUBAC, is expected to be an additional effective strategy to treat neurodegenerative diseases.

Deubiquitinase OTUD1 Resolves Stalled Translation on polyA and Rare Codon Rich mRNAs

OTUD1 is a deubiquitinating enzyme involved in many cellular processes including cancer and innate, immune signaling pathways. Here, we perform a proximity labeling-based interactome study that identifies OTUD1 largely present in the translation and RNA metabolism protein complexes. Biochemical analysis validates OTUD1 association with ribosome subunits, elongation factors and the E3 ubiquitin ligase ZNF598 but not with the translation initiation machinery. OTUD1 catalytic activity suppresses polyA triggered ribosome stalling through inhibition of ZNF598-mediated RPS10 ubiquitination and stimulates formation of polysomes. Finally, analysis of gene expression suggests that OTUD1 regulates the stability of rare codon rich mRNAs by antagonizing ZNF598.