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.

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.

OTUD1 ameliorates cerebral ischemic injury through inhibiting inflammation by disrupting K63-linked deubiquitination of RIP2.

BACKGROUND: Inflammatory response triggered by innate immunity plays a pivotal element in the progress of ischemic stroke. Receptor-interacting kinase 2 (RIP2) is implicated in maintaining immunity homeostasis and regulating inflammatory response. However, the underlying mechanism of RIP2 in ischemic stroke is still not well understood. Hence, the study investigated the role and the ubiquitination regulatory mechanism of RIP2 in ischemic stroke. METHODS: Focal cerebral ischemia was introduced by middle cerebral artery occlusion (MCAO) in wild-type (WT) and OTUD1-deficient (OTUD1-/-) mice, oxygen glucose deprivation and reoxygenation (OGD/R) models in BV2 cells and primary cultured astrocytes were performed for monitoring of experimental stroke. GSK2983559 (GSK559), a RIP2 inhibitor was intraventricularly administered 30 min before MCAO. Mice brain tissues were collected for TTC staining and histopathology. Protein expression of RIP2, OTUD1, p-NF-κB-p65 and IκBα was determined by western blot. Localization of RIP2 and OTUD1 was examined by immunofluorescence. The change of IL-1ß, IL-6 and TNF-α was detected by ELISA assay and quantitative real-time polymerase chain reaction. Immunoprecipitation and confocal microscopy were used to study the interaction of RIP2 and OTUD1. The activity of NF-κB was examined by dual-luciferase assay. RESULTS: Our results showed upregulated protein levels of RIP2 and OTUD1 in microglia and astrocytes in mice subjected to focal cerebral ischemia. Inhibition of RIP2 by GSK559 ameliorated the cerebral ischemic outcome by repressing the NF-κB activity and the inflammatory response. Mechanistically, OTUD1 interacted with RIP2 and sequentially removed the K63-linked polyubiquitin chains of RIP2, thereby inhibiting NF-κB activation. Furthermore, OTUD1 deficiency exacerbated cerebral ischemic injury in response to inflammation induced by RIP2 ubiquitination. CONCLUSIONS: These findings suggested that RIP2 mediated cerebral ischemic lesion via stimulating inflammatory response, and OTUD1 ameliorated brain injury after ischemia through inhibiting RIP2-induced NF-κB activation by specifically cleaving K63-linked ubiquitination of RIP2.

The deubiquitinase OTUD1 enhances iron transport and potentiates host antitumor immunity.

Although iron is required for cell proliferation, iron-dependent programmed cell death serves as a critical barrier to tumor growth and metastasis. Emerging evidence suggests that iron-mediated lipid oxidation also facilitates immune eradication of cancer. However, the regulatory mechanisms of iron metabolism in cancer remain unclear. Here we identify OTUD1 as the deubiquitinase of iron-responsive element-binding protein 2 (IREB2), selectively reduced in colorectal cancer. Clinically, downregulation of OTUD1 is highly correlated with poor outcome of cancer. Mechanistically, OTUD1 promotes transferrin receptor protein 1 (TFRC)-mediated iron transportation through deubiquitinating and stabilizing IREB2, leading to increased ROS generation and ferroptosis. Moreover, the presence of OTUD1 promotes the release of damage-associated molecular patterns (DAMPs), which in turn recruits the leukocytes and strengthens host immune response. Reciprocally, depletion of OTUD1 limits tumor-reactive T-cell accumulation and exacerbates colon cancer progression. Our data demonstrate that OTUD1 plays a stimulatory role in iron transportation and highlight the importance of OTUD1-IREB2-TFRC signaling axis in host antitumor immunity.

DDIT3 Targets Innate Immunity via the DDIT3-OTUD1-MAVS Pathway To Promote Bovine Viral Diarrhea Virus Replication.

DNA damage-inducible transcript 3 (DDIT3) plays important roles in endoplasmic reticulum (ER) stress-induced apoptosis and autophagy, but its role in innate immunity is not clear. Here, we report that DDIT3 inhibits the antiviral immune response during bovine viral diarrhea virus (BVDV) infection by targeting mitochondrial antiviral signaling (MAVS) in Madin-Darby bovine kidney (MDBK) cells and in mice. BVDV infection induced high DDIT3 mRNA and protein expression. DDIT3 overexpression inhibited type I interferon (IFN-I) and IFN-stimulated gene production, thereby promoting BVDV replication, while DDIT3 knockdown promoted the antiviral innate immune response to suppress viral replication. DDIT3 promoted NF-κB-dependent ovarian tumor (OTU) deubiquitinase 1 (OTUD1) expression. Furthermore, OTUD1 induced upregulation of the E3 ubiquitin ligase Smurf1 by deubiquitinating Smurf1, and Smurf1 degraded MAVS in MDBK cells in a ubiquitination-dependent manner, ultimately inhibiting IFN-I production. Moreover, knocking out DDIT3 promoted the antiviral innate immune response to reduce BVDV replication and pathological changes in mice. These findings provide direct insights into the molecular mechanisms by which DDIT3 inhibits IFN-I production by regulating MAVS degradation.IMPORTANCE Extensive studies have demonstrated roles of DDIT3 in apoptosis and autophagy during viral infection. However, the role of DDIT3 in innate immunity remains largely unknown. Here, we show that DDIT3 is positively regulated in bovine viral diarrhea virus (BVDV)-infected Madin-Darby bovine kidney (MDBK) cells and could significantly enhance BVDV replication. Importantly, DDIT3 induced OTU deubiquitinase 1 (OTUD1) expression by activating the NF-κB signaling pathway, thus increasing intracellular Smurf1 protein levels to degrade MAVS and inhibit IFN-I production during BVDV infection. Together, these results indicate that DDIT3 plays critical roles in host innate immunity repression and viral infection facilitation.

Melatonin induces apoptotic cell death through Bim stabilization by Sp1-mediated OTUD1 upregulation.

Melatonin, secreted by the pineal gland, regulates the circadian rhythms and also plays an oncostatic role in cancer cells. Previously, we showed that melatonin induces the expression of Bim, a pro-apoptotic Bcl-2 protein, at both the transcriptional and post-translational levels. In the present study, we investigated the molecular mechanisms underlying the melatonin-mediated Bim upregulation through post-translational regulation. We found that ovarian tumor domain-containing protein 1 (OTUD1), a deubiquitinase belonging to the OTU protein family, is upregulated by melatonin at the mRNA and protein levels. OTUD1 knockdown inhibited melatonin-induced Bim upregulation and apoptosis in cancer cells. OTUD1 directly interacted with Bim and inhibited its ubiquitination. Melatonin-induced OTUD1 upregulation caused deubiquitination at the lysine 3 residue of Bim, resulting in its stabilization. In addition, melatonin-induced activation of Sp1 was found to be involved in OTUD1 upregulation at the transcriptional level, and pharmacological inhibition and genetic ablation of Sp1 (siRNA) interrupted melatonin-induced OTUD1-mediated Bim upregulation. Furthermore, melatonin reduced tumor growth and induced upregulation of OTUD1 and Bim in a mouse xenograft model. Notably, Bim expression levels correlated with OTUD1 levels in patients with renal clear cell carcinoma. Thus, our results demonstrated that melatonin induces apoptosis by stabilizing Bim via Sp1-mediated OTUD1 upregulation.

The deubiquitinating enzyme OTUD1 antagonizes BH3-mimetic inhibitor induced cell death through regulating the stability of the MCL1 protein.

BACKGROUND: Myeloid cell leukaemia 1 (MCL1) is a pro-survival Bcl-2 family protein that plays important roles in cell survival, proliferation, differentiation and tumourigenesis. MCL1 is a fast-turnover protein that is degraded via an ubiquitination/proteasome-dependent mechanism. Although several E3 ligases have been discovered to promote the ubiquitination of MCL1, the deubiquitinating enzyme (DUB) that regulates its stability requires further investigation. METHODS: The immunoprecipitation was used to determine the interaction between OTUD1 and MCL1. The ubiquitination assays was performed to determine the regulation of MCL1 by OTUD1. The cell viability was used to determine the regulation of BH3-mimetic inhibitor induced cell death by OTUD1. The survival analysis was used to determine the relationship between OTUD1 expression levels and the survival rate of cancer patients. RESULTS: By screening a DUB expression library, we determined that the deubiquitinating enzyme OTUD1 regulates MCL1 protein stability in an enzymatic-activity dependent manner. OTUD1 interacts with MCL1 and promotes its deubiquitination. Knockdown of OTUD1 increases the sensitivity of tumour cells to the BH3-mimetic inhibitor ABT-263, while overexpression of OTUD1 increases tumour cell tolerance of ABT-263. Furthermore, bioinformatics analysis data reveal that OTUD1 is a negative prognostic factor for liver cancer, ovarian cancer and specific subtypes of breast and cervical cancer. CONCLUSIONS: The deubiquitinating enzyme OTUD1 antagonizes BH3-mimetic inhibitor induced cell death through regulating the stability of the MCL1 protein. Thus, OTUD1 could be considered as a therapeutic target for curing these cancers.

Mutations of deubiquitinase OTUD1 are associated with autoimmune disorders.

Dysregulation of innate immunity accompanied by excessive interferon production contributes to autoimmune disease. However, the mechanism by which the immune response is modulated in autoimmune disorders is largely unknown. Here we identified loss-of-function mutations of OTUD1 associated with multiple autoimmune diseases. Under inflammatory conditions, inducible OTUD1 acts as an immune checkpoint and blocks RIG-I-like receptors signaling. As a deubiquitinase, OTUD1 directly interacts with transcription factor IRF3 and removes the K63-linked poly-ubiquitin chains on IRF3 Lysine 98, which inhibits IRF3 nuclear translocation and transcriptional activity. In contrast, OTUD1 mutants impair its suppressive effects on IRF3 via attenuating the OTUD1 deubiquinase activity or its association with IRF3. Moreover, we found FOXO3 signaling is required for OTUD1 induction upon antigenic stimulation. Our data demonstrate that OTUD1 is involved in maintaining immune homeostasis and loss-of-function mutations of OTUD1 enhance the immune response and are associated with autoimmunity.

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.

OTUD1 regulates cytokine expression and related pathways in goose fatty liver by promoting deubiquitination of its target proteins.

Goose fatty liver (or foie gras) does not develop inflammation even in severe steatosis, which is different from human nonalcoholic fatty liver disease (NAFLD), and it is considered as a unique model for NAFLD study. The deubiquitinating enzyme, Ovarian Tumor (OTU)-Deubiquitinase 1 (OTUD1), is involved in various cell biological processes by regulating the expression of cytokines. Its role and mechanism in the formation of goose fatty liver however are not clear yet. This study determined the expression of OTUD1 in goose fatty liver versus normal liver and OTUD1 expression in goose primary liver treated with glucose, fatty acids and insulin using qPCR and immunoblotting assays. OTUD1 gene overexpression and subsequent transcriptome sequencing analysis were performed to identify the differentially expressed genes (DEG) and the pathways where the DEGs are enriched. Immunoprecipitation and protein mass spectrometry were employed to screen the interacting proteins of OTUD1. The results showed that both the mRNA and protein abundances of OTUD1 in goose fatty liver were higher than those of normal liver. In goose primary hepatocytes, palmitic acid and oleic acid both increased the protein levels of OTUD1, while glucose and insulin inhibited the expression of the protein. Overexpression of OTUD1 significantly affected the expression of genes and pathways related to inflammatory/immune responses and cell growth/death. The interacting proteins of OTUD1 are mainly related to membrane transport, immune/inflammatory response, ubiquitination and signaling pathways. The interaction between OTUD1 and AP1G1 was validated by co-immunoprecipitation and immunoblotting assays. Consistently, the relative ubiquitination level of AP1G1 in goose fatty liver was lower than that of normal liver, which is correlated with increased protein abundance of AP1G1 and OTUD1 in goose fatty liver. In conclusion, the increased protein abundance of OTUD1 in goose fatty liver can regulate the expression of cytokines and related pathways during the formation of goose fatty liver by promoting the deubiquitination of the interacting proteins of OTUD1, including AP1G1.

OTUD1 enhances gastric cancer aggressiveness by deubiquitinating EBV-encoded protein BALF1 to stabilize the apoptosis inhibitor Bcl-2.

The Epstein-Barr virus (EBV) is implicated in several cancers, including EBV-associated gastric cancer (EBVaGC). This study focuses on EBV-encoded BALF1 (BamH1 A fragment leftward reading frame 1), a key apoptosis regulator in EBV-related cancers, whose specific impact on EBVaGC was previously unknown. Our findings indicate that BALF1 overexpression in gastric cancer cells significantly enhances their proliferation, migration, and resistance to chemotherapy-induced apoptosis, confirming BALF1's oncogenic potential. A novel discovery is that BALF1 undergoes degradation via the ubiquitin-proteasome pathway. Through analysis of 69 deubiquitinating enzymes (DUBs), ovarian tumor protease (OTU) domain-containing protein 1 (OTUD1) emerged as a vital regulator for maintaining BALF1 protein stability. Furthermore, BALF1 was found to play a role in regulating the stability of the B-cell lymphoma-2 (Bcl-2) protein, increasing its levels through deubiquitination. This mechanism reveals BALF1's multifaceted oncogenic role in gastric cancer, as it contributes both directly and indirectly to cancer progression, particularly by stabilizing Bcl-2, known for its anti-apoptotic characteristics. These insights significantly deepen our understanding of EBV's involvement in the pathogenesis of gastric cancer. The elucidation of OTUD1's role in BALF1 regulation and its influence on Bcl-2 stabilization provide new avenues for therapeutic intervention in EBVaGC, bridging the gap between viral oncogenesis and cellular protein regulation and offering a more holistic view of gastric cancer development under the influence of EBV.

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.

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 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.

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.

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.

VE-822 upregulates the deubiquitinase OTUD1 to stabilize FHL1 to inhibit the progression of lung adenocarcinoma.

BACKGROUND: The deubiquitinase ovarian tumor domain-containing 1 (OTUD1) has been considered as a tumor suppressor in many tumors, but there is minimal research on the role of OTUD1 in lung adenocarcinoma (LUAD) pathogenesis. METHODS: Bioinformatics analyses and western blot were applied for investigating OTUD1 expression in lung cancer and the drug that upregulated OTUD1. Kaplan-Meier analysis with log-rank test was used for survival analyses. IP-MS and co-IP were performed for identifying potential protein interactions with OTUD1. In vitro and in vivo assays were used for exploring the function of OTUD1 during the progression of LUAD. RESULTS: OTUD1 was dramatically downregulated in tumors and cell lines of human lung cancer. OTUD1 inhibited proliferation and migration of lung cancer cells in vitro. Moreover, OTUD1 inhibited growth of xenografts in nude mice and formation of primary lung tumors in urethane-induced lung cancer model. Mechanistically, we showed that OTUD1 deubiquitinated and stabilized FHL1. Furthermore, we listed and identified VE-822 as a candidate agonist for OTUD1. VE-822 inhibited proliferation of lung adenocarcinoma both in vitro and in vivo. CONCLUSION: These results indicated that the deubiquitinase OTUD1, which was upregulated by VE-822, inhibited the progression of LUAD in vitro and in vivo by deubiquitinating and stabilizing FHL1.

The Deubiquitinase OTUD1 Suppresses Secretory Neutrophil Polarization And Ameliorates Immunopathology of Periodontitis.

Tissue-infiltrating neutrophils (TINs) secrete various signaling molecules to establish paracrine communication within the inflammatory milieu. It is imperative to identify molecular mediators that control this secretory phenotype of TINs. The present study uncovers a secretory neutrophil subset that exhibits increased pro-inflammatory cytokine production and enhanced migratory capacity which is highly related with periodontal pathogenesis. Further analysis identifies the OTU domain-containing protein 1 (OTUD1) plays a regulatory role in this secretory neutrophil polarization. In human and mouse periodontitis, the waning of inflammation is correlated with OTUD1 upregulation, whereas severe periodontitis is induced when neutrophil-intrinsic OTUD1 is depleted. Mechanistically, OTUD1 interacts with SEC23B, a component of the coat protein II complex (COPII). By removing the K63-linked polyubiquitin chains on SEC23B Lysine 81, the deubiquitinase OTUD1 negatively regulates the COPII secretory machinery and limits protein ER-to-Golgi trafficking, thus restricting the surface expression of integrin-regulated proteins, CD9 and CD47. Accordingly, blockade of protein transport by Brefeldin A (BFA) curbs recruitment of Otud1-deficient TINs and attenuates inflammation-induced alveolar bone destruction. The results thus identify OTUD1 signaling as a negative feedback loop that limits the polarization of neutrophils with secretory phenotype and highlight the potential application of BFA in the treatment of periodontal inflammation.

OTUD1 chemosensitizes triple-negative breast cancer to doxorubicin by modulating P16 expression.

Chemotherapy remains a critical component of triple-negative breast cancer (TNBC) treatment; however, patients often develop resistance to chemotherapeutic agents. Accumulating evidence indicates that deubiquitylases (DUBs) play pivotal roles in regulating cell proliferation, differentiation, apoptosis, and tumorigenesis. Deubiquitylase OTUD1 is considered a tumor suppressor in various cancers, yet its role in doxorubicin sensitivity in breast cancer patients remains inadequately understood. In this study, we investigated the expression levels and prognostic role of OTUD1 in breast cancer. Our findings demonstrated that OTUD1 was downregulated in TNBC, and lower OTUD1 expression levels were correlated with poor prognosis. We utilized the CCK-8 cell viability assay, flow cytometric analysis, and a TNBC mouse xenograft model to examine the influence of OTUD1 on doxorubicin (DOX) chemotherapy sensitivity in vitro and in vivo. Western blot and immunohistochemistry were employed to explore the correlation between OTUD1 and P16. Our results indicated that upregulation of OTUD1 expression inhibits TNBC cell proliferation and enhances its sensitivity to doxorubicin. Additionally, rescue experiments confirmed that the chemosensitizing effect of OTUD1 overexpression could be reversed by the inhibition of P16. Therefore, our findings reveal that OTUD1 sensitizes TNBC cells to DOX by upregulating P16 expression, suggesting a potential new diagnostic biomarker and therapeutic target for the future treatment of TNBC.

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.