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Neoplasia (New York, N.Y.) Jun 2024Increased mutational burden and EBV load have been revealed from normal tissues to Epstein-Barr virus (EBV)-associated gastric carcinomas (EBVaGCs). BPLF1, encoded by...
Increased mutational burden and EBV load have been revealed from normal tissues to Epstein-Barr virus (EBV)-associated gastric carcinomas (EBVaGCs). BPLF1, encoded by EBV, is a lytic cycle protein with deubiquitinating activity has been found to participate in disrupting repair of DNA damage. We first confirmed that BPLF1 gene in gastric cancer (GC) significantly increased the DNA double strand breaks (DSBs). Ubiquitination mass spectrometry identified histones as BPLF1 interactors and potential substrates, and co-immunoprecipitation and in vitro experiments verified that BPLF1 regulates H2Bub by targeting Rad6. Over-expressing Rad6 restored H2Bub but partially reduced γ-H2AX, suggesting that other downstream DNA repair processes were affected. mRNA expression of BRCA2 were significantly down-regulated by next-generation sequencing after over-expression of BPLF1, and over-expression of p65 facilitated the repair of DSBs. We demonstrated BPLF1 may lead to the accumulation of DSBs by two pathways, reducing H2B ubiquitination (H2Bub) and blocking homologous recombination which may provide new ideas for the treatment of gastric cancer.
PubMed: 38875930
DOI: 10.1016/j.neo.2024.101012 -
Brain : a Journal of Neurology Jun 2024USP25 encodes ubiquitin-specific proteases 25, a key member of deubiquitinating enzyme family and is involved in neural fate determination. Although abnormal expression...
USP25 encodes ubiquitin-specific proteases 25, a key member of deubiquitinating enzyme family and is involved in neural fate determination. Although abnormal expression in Down's syndrome was reported previously, the specific role of USP25 in human diseases has not been defined. In this study, we performed trio-based whole exome sequencing in a cohort of 319 cases (families) with generalized epilepsy of unknown etiology. Five heterozygous USP25 variants including two de novo and three co-segregated variants were determined in eight individuals affected by generalized seizures and/or febrile seizures from five unrelated families. The frequency of USP25 variants showed a significantly high aggregation in this cohort compared to the East Asian population and all populations in the gnomAD database. The mean onset ages of febrile and afebrile seizures were 10 months (infancy) and 11.8 years (juvenile), respectively. The patients achieved seizure freedom except one had occasional nocturnal seizures at the last follow-up. Two patients exhibited intellectual disability. Usp25 was ubiquitously expressed in mouse brain with two peaks on embryonic days (E14‒E16) and postnatal day 21, respectively. Similarly, USP25 expressed in fetus/early childhood stage with a second peak at approximately 12‒20 years old in human brain, consistent with the seizure onset age at infancy and juvenile in the patients. To investigate the functional impact of USP25 deficiency in vivo, we established Usp25 knock-out mice, which showed increased seizure susceptibility compared to wild-type mice in pentylenetetrazol-induced seizure test. To explore the impact of USP25 variants, we employed multiple functional detections. In HEK293T cells, the severe phenotype associated variant (p.Gln889Ter) led to a significant reduction of mRNA and protein expressions but formed a stable truncated dimers with increment of deubiquitinating enzyme activities and abnormal cellular aggregations, indicating a gain-of-function effect. The p.Gln889Ter and p.Leu1045del increased neuronal excitability in mice brain, with a higher firing ability in p.Gln889Ter. These functional impairments align with the severity of the observed phenotypes, suggesting a genotype-phenotype correlation. Hence, a moderate association between USP25 and epilepsy was noted, indicating USP25 is potentially a predisposing gene for epilepsy. Our results from Usp25 null mice and the patient-derived variants indicated that USP25 would play epileptogenic role via loss-of-function or gain-of-function effects. The truncated variant p.Gln889Ter would have profoundly different effect on epilepsy. Together, our results underscore the significance of USP25 heterozygous variants in epilepsy, thereby highlighting the critical role of USP25 in the brain.
PubMed: 38875478
DOI: 10.1093/brain/awae191 -
Renal Failure Dec 2024As a pattern recognition receptor, Toll-like receptor 4 (TLR4) is crucial for the development and progression of acute kidney injury (AKI). This study aims to explore...
Usp9x contributes to the development of sepsis-induced acute kidney injury by promoting inflammation and apoptosis in renal tubular epithelial cells via activation of the TLR4/nf-κb pathway.
As a pattern recognition receptor, Toll-like receptor 4 (TLR4) is crucial for the development and progression of acute kidney injury (AKI). This study aims to explore whether the deubiquitinase Usp9x influences the TLR4/NF-B pathway to cause sepsis-induced acute kidney injury (S-AKI). The model of AKI was established in Sprague-Dawley rats using the cecal ligation and puncture (CLP) method, while renal tubular epithelial cell NRK-52E was stimulated with lipopolysaccharide (LPS) . All plasmids were transfected into NRK-52E cells according to the indicated group. The deubiquitinase of TLR4 was predicted by the online prediction software Ubibrowser. Subsequently, Western blot and Pearson correlation analysis identified Usp9x protein as a potential candidate. Co-IP analysis verified the interaction between TLR4 and Usp9x. Further research revealed that overexpression of Usp9x inhibited degradation of TLR4 protein by downregulating its ubiquitination modification levels. Both and experiments observed that interference with Usp9x effectively alleviated the inflammatory response and apoptosis of renal tubular epithelial cells (RTECs) induced by CLP or LPS, whereas overexpression of TLR4 reversed this situation. Transfection with sh-Usp9x in NRK-52E cells suppressed the expression of proteins associated with the TLR4/NF-κB pathway induced by LPS. Moreover, the overexpression of TLR4 reversed the effect of sh-Usp9x transfection. Therefore, the deubiquitinase Usp9x interacts with TLR4, leading to the upregulation of its expression through deubiquitination modification, and the activation of the TLR4/NF-κB signaling pathway, thereby promoting inflammation and apoptosis in renal tubular epithelial cells and contributing to sepsis-induced acute kidney injury.
Topics: Animals; Toll-Like Receptor 4; Acute Kidney Injury; Sepsis; Apoptosis; Rats, Sprague-Dawley; NF-kappa B; Rats; Epithelial Cells; Signal Transduction; Kidney Tubules; Ubiquitin Thiolesterase; Male; Inflammation; Disease Models, Animal; Cell Line; Lipopolysaccharides; Ubiquitination
PubMed: 38874156
DOI: 10.1080/0886022X.2024.2361089 -
Journal of Medicinal Chemistry Jun 2024Papain-like protease (PLpro) is a promising therapeutic target for its pivotal role in the life cycle of SARS-CoV-2. A series of 1,2,4-oxadiazole derivatives was...
Design, Synthesis, and Biological Evaluation of 1,2,4-Oxadiazole Derivatives Containing an Aryl Carboxylic Acid Moiety as Potent Sarbecovirus Papain-like Protease Inhibitors.
Papain-like protease (PLpro) is a promising therapeutic target for its pivotal role in the life cycle of SARS-CoV-2. A series of 1,2,4-oxadiazole derivatives was designed and synthesized via a ring formation strategy based on SARS-CoV-2 PLpro-GRL0617 complex structure. Systematic structure-activity relationship studies revealed that introducing oxadiazole and aryl carboxylic acid moieties to GRL0617 enhanced the enzymatic inhibition activity, affinity, and deubiquitination capacity toward PLpro. 1,2,4-Oxadiazole compounds and , which had PLpro inhibition activity (IC = 1.8 and 1.0 μM) and antiviral activity against SARS-CoV-2 (EC = 5.4 and 4.3 μM), exhibited good metabolic stability ( > 93.2 min) and higher plasma exposure (AUC = 17,380.08 and 24,289.76 ng·h/mL) in mice. Especially, compound with moderate oral bioavailability of 39.1% and potent antiviral activity is worthy of further studies . Our findings provide a new insight for the discovery of antiviral agents targeting PLpro.
Topics: Oxadiazoles; Drug Design; Animals; Antiviral Agents; Structure-Activity Relationship; SARS-CoV-2; Mice; Humans; Carboxylic Acids; Molecular Docking Simulation; Protease Inhibitors; COVID-19 Drug Treatment; Coronavirus Papain-Like Proteases
PubMed: 38871484
DOI: 10.1021/acs.jmedchem.4c00534 -
Access Microbiology 2024KSHV viral FLICE inhibitory protein (vFLIP) is a potent activator of NF-κB signalling and an inhibitor of apoptosis and autophagy. Inhibition of vFLIP function and...
KSHV viral FLICE inhibitory protein (vFLIP) is a potent activator of NF-κB signalling and an inhibitor of apoptosis and autophagy. Inhibition of vFLIP function and NF-κB signalling promotes lytic reactivation. Here we provide evidence for a novel function of vFLIP through inhibition of the deubiquitinating (DUB) activity of the negative regulator, A20. We demonstrate direct interaction of vFLIP with Itch and A20 and provide evidence for subsequent loss of A20 DUB activity. Our results provide further insight into the function of vFLIP in the regulation of NF-κB signalling.
PubMed: 38868372
DOI: 10.1099/acmi.0.000625.v4 -
Journal of Gastroenterology Jun 2024Accumulating evidence has shown that the NOD-like receptor protein 3 (NLRP3) inflammasome plays a crucial role in the inflammatory cascades involved in the development...
BACKGROUND
Accumulating evidence has shown that the NOD-like receptor protein 3 (NLRP3) inflammasome plays a crucial role in the inflammatory cascades involved in the development of acute pancreatitis (AP). However, the specific agonist responsible for activating the NLRP3 inflammasome in this process has not yet been identified. The purpose of this study is to clarify whether heparan sulfate (HS) works as an NLRP3 inflammasome activator to evoke inflammatory cascades in the progression of AP.
METHODS
Two experimental mouse models of AP were utilized to investigate the pro-inflammatory activity of HS in the development of AP by measuring the secretion of inflammatory cytokines and the neutrophil infiltration in pancreatic tissue. The ability of HS to activate the NLRP3 inflammasome was evaluated both in vitro and in vivo. The nuclear factor kappa B (NF-κB)-mediated expression of NLRP3 inflammasome components in response to HS treatment was determined to decipher the role of HS in transcriptional priming of NLRP3 inflammasome. Furthermore, HS-triggered deubiquitination of NLRP3 was analyzed to reveal the promoting effect of HS on the NLRP3 inflammasome priming via a non-transcriptional pathway.
RESULTS
High plasma level of HS was observed with a positive correlation to that of inflammatory cytokines in AP mice. Administration of HS to mice resulted in an exacerbated inflammatory profile, while reducing HS production by an inhibitor of heparanase significantly attenuated inflammatory response. Pharmacological inhibition or genetic deletion of NLRP3 substantially suppressed the HS-stimulated elevation of IL-1β levels in AP mice. The in vitro data demonstrated that HS primarily serves as a priming signal for the activation of the NLRP3 inflammasome. HS possesses the ability to increase the transcriptional activity of NF-κB and TLR4/NF-κB-driven transcriptional pathway is employed for NLRP3 inflammasome priming. Moreover, HS-induced deubiquitination of NLRP3 is another pathway responsible for non-transcriptional priming of NLRP3 inflammasome.
CONCLUSIONS
Our current work has unveiled HS as a new activator of the NLRP3 inflammasome responsible for the secondary inflammatory cascades during the development of AP, highlighting the HS-NLRP3 pathway as a potential target for future preventive and therapeutic approaches of AP.
PubMed: 38864913
DOI: 10.1007/s00535-024-02127-6 -
Diagnostic Pathology Jun 2024Osteosarcoma is a bone tumor that is characterized by high malignancy and a high mortality rate, and that originates from primitive osteoblastic mesenchymal cells and is...
BACKGROUND
Osteosarcoma is a bone tumor that is characterized by high malignancy and a high mortality rate, and that originates from primitive osteoblastic mesenchymal cells and is most common in rapidly growing long bones. PSMD14, also known as RPN11 or POH1, is a member of the JAMM isopeptidase family, which is able to remove the substrate protein ubiquitination label, thereby regulating the stability and function of the substrate protein. In this study, we explored the expression and potential biological significance of the PSMD14 deubiquitinating enzyme in osteosarcoma.
METHODS
Immunohistochemical methods were used to detect the expression of PSMD14 in biopsies of 91 osteosarcoma patients, and the specimens were classified into high and low PSMD14 expression groups. The correlation between PSMD14 expression and clinical indicators and prognosis was compared.SiRNA was used to downregulate PSMD14 in two osteosarcoma cell lines (HOS and SJSA-1), and the effects of downregulation of PSMD14 on the viability, proliferation, and invasion ability of osteosarcoma cells were analyzed.
RESULTS
We identified significant differences in recurrence, metastasis, and survival time of the osteosarcoma patients on the basis of PSMD14 expression. High expression of PSMD14 in osteosarcoma patients was associated with a low survival rate and high risk of metastasis and recurrence. Down-regulation of PSMD14 inhibited the viability, proliferation, and invasiveness of osteosarcoma cell lines.
CONCLUSIONS
PSMD14 may be a new prognostic marker and therapeutic target for osteosarcoma.
Topics: Osteosarcoma; Humans; Bone Neoplasms; Male; Biomarkers, Tumor; Female; Prognosis; Cell Line, Tumor; Adult; Cell Proliferation; Proteasome Endopeptidase Complex; Adolescent; Young Adult; Middle Aged; Neoplasm Invasiveness; Trans-Activators
PubMed: 38863002
DOI: 10.1186/s13000-024-01489-y -
BioRxiv : the Preprint Server For... May 2024The ubiquitin-like protein ISG15 (interferon-stimulated gene 15) regulates the host response to bacterial and viral infections through its conjugation to proteins...
The ubiquitin-like protein ISG15 (interferon-stimulated gene 15) regulates the host response to bacterial and viral infections through its conjugation to proteins (ISGylation) following interferon production. ISGylation is antagonized by the highly specific cysteine protease USP18, which is the major deISGylating enzyme. However, mechanisms underlying USP18's extraordinary specificity towards ISG15 remains elusive. Here, we show that USP18 interacts with its paralog USP41, whose catalytic domain shares 97% identity with USP18. However, USP41 does not act as a deISGylase, which led us to perform a comparative analysis to decipher the basis for this difference, revealing molecular determinants of USP18's specificity towards ISG15. We found that USP18 C-terminus, as well as a conserved Leucine at position 198, are essential for its enzymatic activity and likely act as functional surfaces based on AlphaFold predictions. Finally, we propose that USP41 antagonizes conjugation of the understudied ubiquitin-like protein FAT10 (HLA-F adjacent transcript 10) from substrates in a catalytic-independent manner. Altogether, our results offer new insights into USP18's specificity towards ISG15, while identifying USP41 as a negative regulator of FAT10 conjugation.
PubMed: 38853827
DOI: 10.1101/2024.05.28.596309 -
Cancer Letters Aug 2024B7-H4 is an immune checkpoint crucial for inhibiting CD8 T-cell activity. A clinical trial is underway to investigate B7-H4 as a potential immunotherapeutic agent....
B7-H4 is an immune checkpoint crucial for inhibiting CD8 T-cell activity. A clinical trial is underway to investigate B7-H4 as a potential immunotherapeutic agent. However, the regulatory mechanism of B7-H4 degradation via the ubiquitin-proteasome pathway (UPP) remains poorly understood. In this study, we discovered that proteasome inhibitors effectively increased B7-H4 expression, while EGFR-activating mutants promoted B7-H4 expression through the UPP. We screened B7-H4 binding proteins by co-immunoprecipitation and mass spectrometry and found that USP2a acted as a deubiquitinase of B7-H4 by removing K48- and K63-linked ubiquitin chains from B7-H4, leading to a reduction in B7-H4 degradation. EGFR mutants enhanced B7-H4 stability by upregulating USP2a expression. We further investigated the role of USP2a in tumor growth in vivo. Depletion of USP2a in L858R/LLC cells inhibited tumor cell proliferation, consequently suppressing tumor growth in immune-deficient nude mice by destabilizing downstream molecules such as Cyclin D1. In an immune-competent C57BL/6 mouse tumor model, USP2a abrogation facilitated infiltration of CD95CD8 effector T cells and hindered infiltration of Tim-3+CD8 and LAG-3+CD8 exhausted T cells by destabilizing B7-H4. Clinical lung adenocarcinoma samples showed a significant correlation between B7-H4 abundance and USP2a expression, indicating the contribution of the EGFR/USP2a/B7-H4 axis to tumor immunosuppression. In summary, this study elucidates the dual effects of USP2a in tumor growth by stabilizing Cyclin D1, promoting tumor cell proliferation, and stabilizing B7-H4, contributing to tumor immunosuppression. Therefore, USP2a represents a potential target for tumor therapy.
Topics: Animals; Humans; ErbB Receptors; Ubiquitin Thiolesterase; Mice; V-Set Domain-Containing T-Cell Activation Inhibitor 1; Lung Neoplasms; Adenocarcinoma of Lung; Cell Line, Tumor; Mice, Nude; Cell Proliferation; Mutation; Mice, Inbred C57BL; CD8-Positive T-Lymphocytes; Proteasome Endopeptidase Complex
PubMed: 38849009
DOI: 10.1016/j.canlet.2024.217020 -
Cancer Science Jun 2024Ubiquitin-specific peptidase 15 (USP15), a critical deubiquitinating enzyme, has been demonstrated to improve substrate stabilization by hydrolyzing the bond between the...
Ubiquitin-specific peptidase 15 (USP15), a critical deubiquitinating enzyme, has been demonstrated to improve substrate stabilization by hydrolyzing the bond between the substrate and ubiquitin, and is implicated in multiple carcinogenic processes. Prompted by the information cited from The Cancer Genome Atlas (TCGA) database and the Cancer Proteogenomic Data Analysis Site (cProSite), USP15 is selectively overexpressed in clear cell renal cell carcinoma (ccRCC) samples. We aimed to investigate the function of USP15 on ccRCC malignant features, which was emphasized in its deubiquitination of SHC adaptor protein 1 (SHC1). The overexpression of USP15 promoted the capacity of proliferation, migration, and invasion in ccRCC CAKI1 and 769-P cells, and these malignant biological properties were diminished by USP15 deletion in 786-O cells. USP15 accelerated tumor growth and lung metastasis in vivo. In addition, deubiquitinase USP15 was further identified as a new protector for SHC1 from degradation by the ubiquitination pathway, the post-translational modification. In sequence, transcription factor activating enhancer binding protein 4 (TFAP4) was shown to be partly responsible for USP15 expression at the level of transcription, as manifested by the chromatin immunoprecipitation and pull-down assay. Based on the in vitro and in vivo data, we postulate that USP15 regulated by TFAP4 transcriptionally deteriorates ccRCC malignant biological properties via stabilizing SHC1 by deubiquitination.
PubMed: 38847328
DOI: 10.1111/cas.16237