Ferroptosis constitutes a pivotal pathological event following spinal cord injury and presents substantial challenges to the restoration of neurological function.Cystine-glutamate transporter SLC7A11 is essential for ...Ferroptosis constitutes a pivotal pathological event following spinal cord injury and presents substantial challenges to the restoration of neurological function.Cystine-glutamate transporter SLC7A11 is essential for maintaining cellular redox homeostasis and resisting ferroptosis.However,the mechanisms underlying neuronal ferroptosis caused by SLC7A11 downregulation following spinal cord injury remain unclear.Herein,we provide evidence that tumor protein 53,a negative regulator of SLC7A11,was significantly upregulated post-spinal cord injury.Transcriptomic analysis indicated that tumor protein 53 was associated with injury severity.We subsequently confirmed that tumor protein 53 inhibition restored the expressions of SLC7A11 and glutathione peroxidase 4,alleviated neuronal ferroptosis,and improved neurological function in a contusion spinal cord injury rat model.The regulatory effects of tumor protein 53 on the transcription and ubiquitination of SLC7A11 were further elucidated using chromatin immunoprecipitation polymerase chain reaction and cleavage under targets and tagmentation techniques.Additionally,Kelch-like protein 4,an E3 ubiquitin ligase adaptor,was demonstrated to play an important role in the tumor protein 53-mediated ubiquitination of SLC7A11.In summary,the present study elucidated the possible mechanisms of tumor protein 53-mediated neuronal ferroptosis in spinal cord injury,thereby providing potential targets and insights for clinical translation.展开更多
Oral squamous cell carcinoma(OSCC)is the most common head and neck malignancy worldwide,accounting for more than 90%of all oral cancers,and is characterized by high invasiveness and poor long-term prognosis.Its etiolo...Oral squamous cell carcinoma(OSCC)is the most common head and neck malignancy worldwide,accounting for more than 90%of all oral cancers,and is characterized by high invasiveness and poor long-term prognosis.Its etiology is multifactorial,involving tobacco use,alcohol consumption,and human papillomavirus(HPV)infection.Oral leukoplakia and erythroplakia are the main precancerous lesions lesions,with oral leukoplakia being the most common.Both OSCC and premalignant lesions are closely associated with aberrant activation of multiple signaling pathways.Post-translational modifications(such as ubiquitination and deubiquitination)play key roles in regulating these pathways by controlling protein stability and activity.Growing evidence indicates that dysregulated ubiquitination/deubiquitination can mediate OSCC initiation and progression via aberrant activation of signaling pathways.The ubiquitination/deubiquitination process mainly involves E3 ligases(E3s)that catalyze substrate ubiquitination,deubiquitinating enzymes(DUBs)that remove ubiquitin chains,and the 26S proteasome complex that degrades ubiquitinated substrates.Abnormal expression or mutation of E3s and DUBs can lead to altered stability of critical tumorrelated proteins,thereby driving OSCC initiation and progression.Therefore,understanding the aberrantly activated signaling pathways in OSCC and the ubiquitination/deubiquitination mechanisms within these pathways will help elucidate the molecular mechanisms and improve OSCC treatment by targeting relevant components.Here,we summarize four aberrantly activated signaling pathways in OSCC―the PI3K/AKT/mTOR pathway,Wnt/β-catenin pathway,Hippo pathway,and canonical NF-κB pathway―and systematically review the regulatory mechanisms of ubiquitination/deubiquitination within these pathways,along with potential drug targets.PI3K/AKT/mTOR pathway is aberrantly activated in approximately 70%of OSCC cases.It is modulated by E3s(e.g.,FBXW7 and NEDD4)and DUBs(e.g.,USP7 and USP10):FBXW7 and USP10 inhibit signaling,while NEDD4 and USP7 potentiate it.Aberrant activation of the Wnt/β-catenin pathway leads toβ-catenin nuclear translocation and induction of cell proliferation.This pathway is modulated by E3s(e.g.,c-Cbl and RNF43)and DUBs(e.g.,USP9X and USP20):c-Cbl and RNF43 inhibit signaling,while USP9X and USP20 potentiate it.Hippo pathway inactivation permits YAP/TAZ to enter the nucleus and promotes cancer cell metastasis.This pathway is modulated by E3s(e.g.,CRL4^(DCAF1) and SIAH2)and DUBs(e.g.,USP1 and USP21):CRL4^(DCAF1) and SIAH2 inhibit signaling,while USP1 and USP21 potentiate it.Persistent activation of the canonical NF-κB pathway is associated with an inflammatory microenvironment and chemotherapy resistance.This pathway is modulated by E3s(e.g.,TRAF6 and LUBAC)and DUBs(e.g.,A20 and CYLD):A20 and CYLD inhibit signaling,while TRAF6 and LUBAC potentiate it.Targeting these E3s and DUBs provides directions for OSCC drug research.Small-molecule inhibitors such as YCH2823(a USP7 inhibitor),GSK2643943A(a USP20 inhibitor),and HOIPIN-8(a LUBAC inhibitor)have shown promising antitumor activity in preclinical models;PROTAC molecules,by binding to surface sites of target proteins and recruiting E3s,achieve targeted ubiquitination and degradation of proteins insensitive to small-molecule inhibitors,for example,PU7-1-mediated USP7 degradation,offering new strategies to overcome traditional drug limitations.Currently,NX-1607(a Cbl-b inhibitor)has entered phase I clinical trials,with preliminary results confirming its safety and antitumor activity.Future research on aberrant E3s and DUBs in OSCC and the development of highly specific inhibitors will be of great significance for OSCC precision therapy.展开更多
BACKGROUND Diabetes has a substantial impact on public health,highlighting the need for novel treatments.Ubiquitination,an intracellular protein modification process,is emerging as a promising strategy for regulating ...BACKGROUND Diabetes has a substantial impact on public health,highlighting the need for novel treatments.Ubiquitination,an intracellular protein modification process,is emerging as a promising strategy for regulating pathological mechanisms.We hypothesize that ubiquitination plays a critical role in the development and progression of diabetes and its complications,and that understanding these mechanisms can lead to new therapeutic approaches.AIM To uncover the research trends and advances in diabetes ubiquitination and its complications,we conducted a bibliometric analysis.METHODS Studies on ubiquitination in diabetes mellitus and its complications were retrieved from the Web of Science Core Collection.Visual mapping analysis was conducted using the CiteSpace software.RESULTS We gathered 791 articles published over the past 23 years,focusing on ubiquitination in diabetes and its associated complications.These articles originated from 54 countries and 386 institutions,with China as the leading contributor.Shanghai Jiao Tong University has the highest number of publications in this field.The most prominent authors contributing to this research area include Wei-Hua Zhang,with Zhang Y being the most frequently cited author.Additionally,The Journal of Biological Chemistry is noted as the most cited in this field.The predominant keywords included expression,activation,oxidative stress,phosphorylation,ubiquitination,degradation,and insulin resistance.CONCLUSION The role of ubiquitination in diabetes and its complications,such as diabetic nephropathy and cardiomyopathy,is a key research focus.However,these areas require further investigations.展开更多
During the process of organizing our original data,we unfortunately identified two error in the figures within our published article.In Fig.1,the online version incorrectly labels the SNI+NAC group as the sham+NAC gro...During the process of organizing our original data,we unfortunately identified two error in the figures within our published article.In Fig.1,the online version incorrectly labels the SNI+NAC group as the sham+NAC group.We have revised the grouping annotations in Fig.1 and have labeled the DHE staining in the figure to present the experimental design more clearly.展开更多
Ring finger protein 122(RNF122),an E3 ubiquitin ligase,orchestrates antiviral immune responses in mammals by targeting retinoic acid-inducible gene 1 and melanoma differentiation-associated gene 5 for ubiquitination.H...Ring finger protein 122(RNF122),an E3 ubiquitin ligase,orchestrates antiviral immune responses in mammals by targeting retinoic acid-inducible gene 1 and melanoma differentiation-associated gene 5 for ubiquitination.However,its functional relevance in teleosts has yet to be clearly defined,particularly regarding the identification of substrate-specific regulatory sites.This study characterized RNF122 from mandarin fish(Siniperca chuatsi),termed scRNF122,and investigated its regulatory impact on stimulator of interferon genes(STING)-mediated antiviral signaling.Results showed that scRNF122 expression was up-regulated in response to mandarin fish ranavirus(MRV)infection,and its overexpression suppressed scSTING-mediated interferon(IFN)production and enhanced MRV replication.Co-immunoprecipitation confirmed a direct interaction between scRNF122 and scSTING.Functional assays demonstrated that scRNF122 facilitated scSTING degradation through the ubiquitin-proteasome pathway,a process impeded by MG132 treatment.Ubiquitination analyses of various scSTING mutants revealed that scRNF122 catalyzed scSTING ubiquitination at K95,K117,and K155 residues.Moreover,scRNF122 significantly impaired scSTING-dependent antiviral responses by engaging negative regulatory elements within the signaling cascade.Overall,scRNF122 was identified as a negative modulator of STING-mediated IFN signaling in mandarin fish,diminishing STING-dependent antiviral activity and promoting its degradation via the ubiquitin-proteasome pathway at lysine residues K95,K117,and K155.These findings provide mechanistic insight into the post-translational control of STING in teleosts and establish a foundation for future investigations into antiviral immune regulation.展开更多
BACKGROUND ANAPC1,a key regulator of the ubiquitination in tumour development,has not been thoroughly studied in hepatocellular carcinoma(HCC).AIM To elucidate the expression of ANAPC1 in HCC and its potential regulat...BACKGROUND ANAPC1,a key regulator of the ubiquitination in tumour development,has not been thoroughly studied in hepatocellular carcinoma(HCC).AIM To elucidate the expression of ANAPC1 in HCC and its potential regulatory mechanism related to ubiquitination.METHODS Bulk RNA(RNA sequencing and microarrays),immunohistochemistry(IHC)tissues,and single-cell RNA sequencing(scRNA-seq)data were integrated to comprehensively investigate ANAPC1 expression in HCC.Clustered regularly interspaced short palindromic repeats analysis was performed to assess growth in HCC cell lines following ANAPC1 knockout.Enrichment analyses were conducted to explore the functions of ANAPC1.ScRNA-seq data was used to examine the cell cycle and metabolic levels.CellChat analysis was applied to investigate the interactions between ANAPC1 and different cell types.The relationship between ANAPC1 expression and drug concentration was analyzed.RESULTS ANAPC1 messenger RNA was found to be upregulated in bulk RNA,IHC tissues samples and malignant hepatocytes.The proliferation of JHH2 cell lines was most significantly inhibited after ANAPC1 knockdown.In biological pathways,the development of HCC was found to be linked to the regulation of ubiquitin-mediated proteolysis.Additionally,scRNA-seq results indicated that highly expressed ANAPC1 was in the G2/M phase,with increased glycolysis/gluconeogenesis activity.A CellChat analysis showed that ANAPC1 was associated with the regulation of the migration inhibitory factor-(cluster of differentiation 74+C-X-C chemokine receptor type 4)pathway.Higher ANAPC1 expression correlated with stronger effects of sorafenib,dasatinib,ibrutinib,lapatinib,nilotinib and afatinib.CONCLUSION The high expression level of ANAPC1 may regulate the cell cycle and metabolic levels of HCC through the ubiquitination-related pathway,thereby promoting disease progression.展开更多
Objective:Osimertinib(OSI)therapy,a cornerstone in treating non-small cell lung cancer(NSCLC),has been severely limited by rapidly developing acquired resistance.Inhibition of bypass activation using a combination str...Objective:Osimertinib(OSI)therapy,a cornerstone in treating non-small cell lung cancer(NSCLC),has been severely limited by rapidly developing acquired resistance.Inhibition of bypass activation using a combination strategy holds promise in overcoming this resistance.Biguanides,with excellent anti-tumor effects,have recently attracted much attention for this potential.The current study investigated whether novel biguanide compounds developed by our team could overcome OSI resistance and the underlying mechanisms were explored.Methods:A comprehensive screening assay using OSI-resistant cells identified the optimal combination of biguanide compounds with OSI.Proteomics,co-immunoprecipitation mass spectrometry,RNA sequencing,and homologous recombination assays were used to elucidate the molecular mechanisms underlying combination therapy.NSCLC tumor tissues,especially OSI-resistant tissues,obtained from our clinic were used to assess the correlations between key proteins and OSI resistance.Results:SMK-010,a highly potent biguanide compound,effectively overcame OSI resistance in vitro and in vivo.Mechanistical studies showed that BMI1/FGFR1 pathway activation is responsible for OSI resistance.Specifically,silencing BMI1 promoted NEDD4-mediated FGFR1 ubiquitination and proteasomal degradation,whereas SMK-010 treatment induced FGFR1 lysosomal degradation.This reduction in FGFR1 levels impaired homologous recombination,increased DNA damage,and surmounted OSI resistance.Analysis of clinical samples revealed overexpression of BMI1 and FGFR1 in NSCLC tissues and represented potential biomarkers for OSI resistance.Conclusions:These findings highlight the crucial role of the BMI1/FGFR1 axis in OSI resistance and provide a rational basis for the future clinical application of the biguanide,SMK-010,in combination with OSI.展开更多
Objective:Gastric cancer(GC)is one of the most common malignancies seen in clinic and requires novel treatment options.Morin is a natural flavonoid extracted from the flower stalk of a highly valuable medicinal plant ...Objective:Gastric cancer(GC)is one of the most common malignancies seen in clinic and requires novel treatment options.Morin is a natural flavonoid extracted from the flower stalk of a highly valuable medicinal plant Prunella vulgaris L.,which exhibits an anti-cancer effect in multiple types of tumors.However,the therapeutic effect and underlying mechanism of morin in treating GC remains elusive.The study aims to explore the therapeutic effect and underlying molecular mechanisms of morin in GC.Methods:For in vitro experiments,the proliferation inhibition of morin was measured by cell counting kit-8 assay and colony formation assay in human GC cell line MKN45,human gastric adenocarcinoma cell line AGS,and human gastric epithelial cell line GES-1;for apoptosis analysis,microscopic photography,Western blotting,ubiquitination analysis,quantitative polymerase chain reaction analysis,flow cytometry,and RNA interference technology were employed.For in vivo studies,immunohistochemistry,biomedical analysis,and Western blotting were used to assess the efficacy and safety of morin in a xenograft mouse model of GC.Results:Morin significantly inhibited the proliferation of GC cells MKN45 and AGS in a dose-and timedependent manner,but did not inhibit human gastric epithelial cells GES-1.Only the caspase inhibitor Z-VAD-FMK was able to significantly reverse the inhibition of proliferation by morin in both GC cells,suggesting that apoptosis was the main type of cell death during the treatment.Morin induced intrinsic apoptosis in a dose-dependent manner in GC cells,which mainly relied on B cell leukemia/lymphoma 2(BCL-2)associated agonist of cell death(BAD)but not phorbol-12-myristate-13-acetate-induced protein 1.The upregulation of BAD by morin was due to blocking the ubiquitination degradation of BAD,rather than the transcription regulation and the phosphorylation of BAD.Furthermore,the combination of morin and BCL-2 inhibitor navitoclax(also known as ABT-737)produced a synergistic inhibitory effect in GC cells through amplifying apoptotic signals.In addition,morin treatment significantly suppressed the growth of GC in vivo by upregulating BAD and the subsequent activation of its downstream apoptosis pathway.Conclusion:Morin suppressed GC by inducing apoptosis,which was mainly due to blocking the ubiquitination-based degradation of the pro-apoptotic protein BAD.The combination of morin and the BCL-2 inhibitor ABT-737 synergistically amplified apoptotic signals in GC cells,which may overcome the drug resistance of the BCL-2 inhibitor.These findings indicated that morin was a potent and promising agent for GC treatment.展开更多
3-Hydroxy-3-methylglutaryl coenzyme A （HMG CoA） reductase produces mevalonate, an important intermediate in the synthesis of cholesterol and essential nonsterol isoprenoids. The reductase is subject to an exorbitant...3-Hydroxy-3-methylglutaryl coenzyme A （HMG CoA） reductase produces mevalonate, an important intermediate in the synthesis of cholesterol and essential nonsterol isoprenoids. The reductase is subject to an exorbitant amount of feedback control through multiple mechanisms that are mediated by sterol and nonsterol end-products of mevalonate metabolism. Here, I will discuss recent advances that shed light on one mechanism for control of reductase, which involves rapid degradation of the enzyme. Accumulation of certain sterols triggers binding of reductase to endoplasmic reticulum （ER） membrane proteins called Insig-1 and Insig-2. Reductase-Insig binding results in recruitment of a membrane-associated ubiquitin ligase called gp78, which initiates ubiquitination of reductase. This ubiquitination is an obligatory reaction for recognition and degradation of reductase from ER membranes by cytosolic 26S proteasomes. Thus, sterol-accelerated degradation of reductase represents an example of how a general cellular process （ER-associated degradation） is used to control an important metabolic pathway （cholesterol synthesis）.展开更多
Post-translational modification is central to protein stability and to the modulation of protein activity. Various types of protein modification, such as phosphorylation, methylation, acetylation, myristoylation, glyc...Post-translational modification is central to protein stability and to the modulation of protein activity. Various types of protein modification, such as phosphorylation, methylation, acetylation, myristoylation, glycosylation, and ubiquitination, have been reported. Among them, ubiquitination distinguishes itself from others in that most of the ubiquitinated proteins are targeted to the 26S proteasome for degradation. The ubiquitin/26S proteasome system constitutes the major protein degradation pathway in the cell. In recent years, the importance of the ubiquitination machinery in the control of numerous eukaryotic cellular functions has been increasingly appreciated. Increasing number of E3 ubiquitin ligases and their substrates, including a variety of essential cellular regulators have been identified. Studies in the past several years have revealed that the ubiquitination system is important for a broad range of plant developmental processes and responses to abiotic and biotic stresses. This review discusses recent advances in the functional analysis of ubiquitination-associated proteins from plants and pathogens that play important roles in plant-microbe interactions.展开更多
DI-3-n-butylphthalide is used to treat mild and moderate acute ischemic stroke.However,the precise underlying mechanism requires further investigation.In this study,we investigated the molecular mechanism of DI-3-n-bu...DI-3-n-butylphthalide is used to treat mild and moderate acute ischemic stroke.However,the precise underlying mechanism requires further investigation.In this study,we investigated the molecular mechanism of DI-3-n-butylphthalide action by various means.We used hydrogen peroxide to induce injury to PC12cells and RAW264.7 cells to mimic neuronal oxidative stress injury in stroke in vitro and examined the effects of DI-3-n-butylphthalide.We found that DI-3-nbutylphthalide pretreatment markedly inhibited the reduction in viability and reactive oxygen species production in PC12 cells caused by hydrogen peroxide and inhibited cell apoptosis.Furthermore,DI-3-n-butylphthalide pretreatment inhibited the expression of the pro-apoptotic genes Bax and Bnip3.DI-3-nbutylphthalide also promoted ubiquitination and degradation of hypoxia inducible factor 1α,the key transcription factor that regulates Bax and Bnip3 genes.These findings suggest that DI-3-n-butylphthalide exhibits a neuroprotective effect on stroke by promoting hypoxia inducible factor-1α ubiquitination and degradation and inhibiting cell apoptosis.展开更多
Polyphyllin I(PPI)purified from Polyphylla rhizomes displays puissant cytotoxicity in many kinds of cancers.Several researches investigated its anti-cancer activity.But novel mechanisms are still worth investigation.T...Polyphyllin I(PPI)purified from Polyphylla rhizomes displays puissant cytotoxicity in many kinds of cancers.Several researches investigated its anti-cancer activity.But novel mechanisms are still worth investigation.This study aimed to explore PPI-induced endoplasmic reticulum(ER)stress as well as the underlying mechanism in non-small cell lung cancer(NSCLC).Cell viability or colony-forming was detected by MTT or crystal violet respectively.Cell cycle,apoptosis,reactive oxygen species(ROS)and mitochondrial membrane potential were assessed by flow cytometry.Gene and protein levels were evaluated by q RT-PCR and immunoblotting respectively.Protein interaction was determined by immunoprecipitation or immunofluorescence assay.Gene overexpression or silencing was carried out by transient transfection with plasmids or small interfering RNAs.The Cancer Genome Atlas(TCGA)database was used for Gene Set Enrichment Analysis(GSEA),survival analysis,gene expression statistics or pathway enrichment assay.PPI inhibited the propagation of NSCLC cells,increased non-viable apoptotic cells,arrested cell cycle at G2/M phase,induced ROS levels but failed to decrease mitochondrial membrane potential.High levels of GRP78 indicates poor prognosis in NSCLC patients.PPI selectively suppressed unfolded protein response(UPR)-induced GRP78 expression,subsequently protected CHOP from GRP78-mediated ubiquitination and degradation.We demonstrated that the natural product PPI,obtained from traditional herbal medicine,deserves for further study as a valuable candidate for lead compound in the chemotherapy of NSCLC.展开更多
Background:NOD-like receptor family CARD domain containing 3(NLRC3)plays an important role in both innate and adaptive immunity.This study was to explore the function and related mechanisms of NLRC3 in a hypoxia/reoxy...Background:NOD-like receptor family CARD domain containing 3(NLRC3)plays an important role in both innate and adaptive immunity.This study was to explore the function and related mechanisms of NLRC3 in a hypoxia/reoxygenation(H/R)-induced inflammatory response in RAW264.7 cells.Methods:Liver ischemia-reperfusion(I/R)model in mice and H/R model in RAW264.7 cells were constructed.Western blotting was used to determine the protein expression level of NLRC3 in liver tissue and NLRC3,TRAF6,p–p65,p65,IκB–α,and the K63-linked ubiquitination level of TRAF6 in cells.The immunofluorescence assay was performed to evaluate the nuclear level of the NF–κB(p65).ELISA was conducted to measure the content of IL–1βin serum and cell supernatant.The interaction between NLRC3 and TRAF6 in cells was analyzed by the Co-IP assay.Results:The NLRC3 protein level in liver tissue was decreased with the prolongation of reperfusion time(P<0.05).The expression of NLRC3 and IκB–αprotein in RAW264.7 was decreased gradually,while the expression of p–p65 and TRAF6 proteins and K63-linked ubiquitination of TRAF6 were increased gradually with the prolongation of reoxgenation time(P<0.05).The Co-IP assay revealed that NLRC3 and TRAF6 can bind to each other directly.However,NLRC3 had no effect on the expression of TRAF6 protein.The ubiquitination test results showed that the K63-linked ubiquitination level of TRAF6 in H/R+Lv–NLRC3 group was significantly lower than that in the H/R+negative control(NC)group(P<0.05).Moreover,the activation of NF–κB in H/R+Lv–NLRC3 group was inhibited compared with that in the H/R+NC group,and the level of the inflammatory factor IL–1βin the cell culture supernatant was also decreased accordingly(P<0.05).Conclusions:NLRC3 might alleviate H/R-induced inflammation in RAW264.7 cells by inhibiting K63-linked ubiquitination of TRAF6.展开更多
Transcription factor Oct4 plays critical roles in maintaining pluripotency and controlling lineage commitment of embryonic stem cells （ESCs）. Our previous study indicates that Wwp2, a mouse HECT-type E3 ubiquitin li...Transcription factor Oct4 plays critical roles in maintaining pluripotency and controlling lineage commitment of embryonic stem cells （ESCs）. Our previous study indicates that Wwp2, a mouse HECT-type E3 ubiquitin ligase, ubiquitinates Oct4 and promotes its degradation in a heterologous system. However, roles of Wwp2 in regulating en- dogenous Oct4 protein levels as well as molecular characteristics of the function of Wwp2 have not been determined. Here, we report that Wwp2 plays an important role in Oct4 ubiquitination and degradation during differentiation of embryonal carcinoma cells （ECCs）, although it does not appear to affect Oct4 protein levels in the undifferentiated ECCs and ESCs. Importantly, inhibition of Wwp2 expression by specific RNA interference elevates the Oct4 protein level, leading to attenuation in retinoid acid-induced activation of differentiation-related marker genes. Mechanisti- cally, Wwp2 catalyzes Oct4 poly-ubiquitination via the lysine 63 linkage in a dosage-dependent manner. Interest- ingly, Wwp2 also regulates its own ligase activity in a similar manner. Moreover, auto-ubiquitination of Wwp2 occurs through an intra-molecular mechanism. Taken together, these results demonstrate a crucial role of Wwp2 in con- trolling endogenous Oct4 protein levels during differentiation processes of ECCs and suggest an interesting dosage- dependent mechanism for regulating the catalytic activity of the E3 ubiquitin ligase, Wwp2.展开更多
Cyclophilin A (CypA) is a peptidyl-prolyl cis/trans isomerase that interacts with the matrix protein (M1) of influenza A virus (IAV) and restricts virus replication by regulating the ubiquitin–proteasome-mediated deg...Cyclophilin A (CypA) is a peptidyl-prolyl cis/trans isomerase that interacts with the matrix protein (M1) of influenza A virus (IAV) and restricts virus replication by regulating the ubiquitin–proteasome-mediated degradation of M1. However,the mechanism by which CypA regulates M1 ubiquitination remains unknown. In this study, we reported that E3 ubiquitin ligase AIP4 promoted K48-linked ubiquitination of M1 at K102 and K104, and accelerated ubiquitin–proteasome-mediated degradation of M1. The recombinant IAV with mutant M1 (K102 R/K104 R) could not be rescued, suggesting that the ubiquitination of M1 at K102/K104 was essential for IAV replication. Furthermore, CypA inhibited AIP4-mediated M1 ubiquitination by impairing the interaction between AIP4 and M1. More importantly, both the mutations of M1 (K102 R/K104 R) and CypA inhibited the nuclear export of M1, indicating that CypA regulates the cellular localization of M1 via inhibition of AIP4-mediated M1 ubiquitination at K102 and K104, which results in the reduced replication of IAV.Collectively, our findings reveal a novel ubiquitination-based mechanism by which CypA regulates the replication of IAV.展开更多
Fanconi anemia(FA)is a rare recessive hereditary disease characterized clinically by congenital defects,progressive bone-marrow failure,and cancer predisposition.Cells from FA patients exhibit hypersensitivity to DNA ...Fanconi anemia(FA)is a rare recessive hereditary disease characterized clinically by congenital defects,progressive bone-marrow failure,and cancer predisposition.Cells from FA patients exhibit hypersensitivity to DNA cross-linking agents,such as mitomycin C(MMC).To date,at least 12 FA genes have been found deleted or mutated in FA cells,and 10 FA gene products form a core complex involved in FA/BRCA2 DNA repair pathway-FA pathway.The ubiquitin E3 ligase FANCL,an important factor of FA core complex,co-functions with a new ubiquitin conjugating enzyme UBE2T to catalyze the monoubiquitination of FANCD2.FANCD2-Ub binds BRCA2 to form a new complex located in chromatin foci and then take part in DNA repair process.The deubiquitylating enzyme USP1 removes the mono-ubiquitin from FANCD2-Ub following completion of the repair process,then restores the blocked cell cycle to normal order by shutting off the FA pathway.In a word,the FANCD2 activity adjusted exquisitely by ubiquitination and/or deubiquitination in vivo may co-regulate the FA pathway involving in variant DNA repair pathway.展开更多
The adaptor protein NUMB is involved in asymmetric division and cell fate determination and recognized as an antagonist of Notch.Previous studies have proved that Notch activation in osteoblasts contributes to a high ...The adaptor protein NUMB is involved in asymmetric division and cell fate determination and recognized as an antagonist of Notch.Previous studies have proved that Notch activation in osteoblasts contributes to a high bone mass. In this study, however, an osteopenic phenotype was found in 9-week-old mice using osteoblastic specific Col1a1–2.3-Cre to ablate both Numb and its homologue Numbl. The trabecular bone mass decreased dramatically while the cortical bone mass was unaffected. Here, the Notch signal was not activated,while the tensin homologue deleted on human chromosome 10(PTEN), which dephosphorylates phosphatidylinositide 3-kinases, was elevated, attenuating protein kinase B(Akt). The ubiquitination assay revealed that NUMB may physiologically promote PTEN ubiquitination in the presence of neural precursor cell-expressed developmentally downregulated protein 4–1. In addition, the deficiency of Numb/Numbl also activated the Hedgehog pathway through GLI1. This process was found to improve the ratio of the receptor activator of nuclear factor-k B ligand to osteoprotegerin, which enhanced the differentiation of osteoclasts and bone resorption. In conclusion, this study provides an insight into new functons of NUMB and NUMBL on bone homeostasis.展开更多
A major impedance to neuronal regeneration after peripheral nerve injury (PNI) is the activation of various programmed cell death mechanisms in the dorsal root ganglion. Ferroptosis is a form of programmed cell death ...A major impedance to neuronal regeneration after peripheral nerve injury (PNI) is the activation of various programmed cell death mechanisms in the dorsal root ganglion. Ferroptosis is a form of programmed cell death distinguished by imbalance in iron and thiol metabolism, leading to lethal lipid peroxidation. However, the molecular mechanisms of ferroptosis in the context of PNI and nerve regeneration remain unclear. Ferroportin (Fpn), the only known mammalian nonheme iron export protein, plays a pivotal part in inhibiting ferroptosis by maintaining intracellular iron homeostasis. Here, we explored in vitro and in vivo the involvement of Fpn in neuronal ferroptosis. We first delineated that reactive oxygen species at the injury site induces neuronal ferroptosis by increasing intracellular iron via accelerated UBA52-driven ubiquitination and degradation of Fpn, and stimulation of lipid peroxidation. Early administration of the potent arterial vasodilator, hydralazine (HYD), decreases the ubiquitination of Fpn after PNI by binding to UBA52, leading to suppression of neuronal cell death and significant acceleration of axon regeneration and motor function recovery. HYD targeting of ferroptosis is a promising strategy for clinical management of PNI.展开更多
Activation of nuclear factor erythroid 2-related factor 2(Nrf2)by Kelch-like ECH-associated protein 1(Keap1)alkylation plays a central role in anti-inflammatory therapy.However,activators of Nrf2 through alkylation of...Activation of nuclear factor erythroid 2-related factor 2(Nrf2)by Kelch-like ECH-associated protein 1(Keap1)alkylation plays a central role in anti-inflammatory therapy.However,activators of Nrf2 through alkylation of Keap1-Kelch domain have not been identified.Deoxynyboquinone(DNQ)is a natural small molecule discovered from marine actinomycetes.The current study was designed to investigate the anti-inflammatory effects and molecular mechanisms of DNQ via alkylation of Keap1.DNQ exhibited significant anti-inflammatory properties both in vitro and in vivo.The pharmacophore responsible for the anti-inflammatory properties of DNQ was determined to be theα,β-unsaturated amides moieties by a chemical reaction between DNQ and N-acetylcysteine.DNQ exerted anti-inflammatory effects through activation of Nrf2/ARE pathway.Keap1 was demonstrated to be the direct target of DNQ and bound with DNQ through conjugate addition reaction involving alkylation.The specific alkylation site of DNQ on Keap1 for Nrf2 activation was elucidated with a synthesized probe in conjunction with liquid chromatography-tandem mass spectrometry.DNQ triggered the ubiquitination and subsequent degradation of Keap1 by alkylation of the cysteine residue 489(Cys489)on Keap1-Kelch domain,ultimately enabling the activation of Nrf2.Our findings revealed that DNQ exhibited potent anti-inflammatory capacity throughα,β-unsaturated amides moieties active group which specifically activated Nrf2 signal pathway via alkylation/ubiquitination of Keap1-Kelch domain,suggesting the potential values of targeting Cys489 on Keap1-Kelch domain by DNQ-like small molecules in inflammatory therapies.展开更多
TANK-binding kinase 1(TBK1)is a nodal protein involved in multiple signal transduction pathways.In RNA virus-mediated innate immunity,TBK1 is recruited to the prion-like platform formed by MAVS and subsequently activa...TANK-binding kinase 1(TBK1)is a nodal protein involved in multiple signal transduction pathways.In RNA virus-mediated innate immunity,TBK1 is recruited to the prion-like platform formed by MAVS and subsequently activates the transcription factors IRF3/7 and NF-κB to produce type I interferon(IFN)and proinflammatory cytokines for the signaling cascade.In this study,TRAF7 was identified as a negative regulator of innate immune signaling.TRAF7 interacts with TBK1 and promotes K48-linked polyubiquitination and degradation of TBK1 through its RING domain,impairing the activation of IRF3 and the production of IFN-β.In addition,we found that the conserved cysteine residues at position 131 of TRAF7 are necessary for its function toward TBK1.Knockout of TRAF7 could facilitate the activation of IRF3 and increase the transcript levels of downstream antiviral genes.These data suggest that TRAF7 negatively regulates innate antiviral immunity by promoting the K48-linked ubiquitination of TBK1.展开更多
基金supported by the National Natural Science Foundation of China,Nos.81672161,81871785,82372411(to ZY)the Health Research Project of Health Commission of Anhui Province,No.AHWJ2023A30106(to YX).
文摘Ferroptosis constitutes a pivotal pathological event following spinal cord injury and presents substantial challenges to the restoration of neurological function.Cystine-glutamate transporter SLC7A11 is essential for maintaining cellular redox homeostasis and resisting ferroptosis.However,the mechanisms underlying neuronal ferroptosis caused by SLC7A11 downregulation following spinal cord injury remain unclear.Herein,we provide evidence that tumor protein 53,a negative regulator of SLC7A11,was significantly upregulated post-spinal cord injury.Transcriptomic analysis indicated that tumor protein 53 was associated with injury severity.We subsequently confirmed that tumor protein 53 inhibition restored the expressions of SLC7A11 and glutathione peroxidase 4,alleviated neuronal ferroptosis,and improved neurological function in a contusion spinal cord injury rat model.The regulatory effects of tumor protein 53 on the transcription and ubiquitination of SLC7A11 were further elucidated using chromatin immunoprecipitation polymerase chain reaction and cleavage under targets and tagmentation techniques.Additionally,Kelch-like protein 4,an E3 ubiquitin ligase adaptor,was demonstrated to play an important role in the tumor protein 53-mediated ubiquitination of SLC7A11.In summary,the present study elucidated the possible mechanisms of tumor protein 53-mediated neuronal ferroptosis in spinal cord injury,thereby providing potential targets and insights for clinical translation.
文摘Oral squamous cell carcinoma(OSCC)is the most common head and neck malignancy worldwide,accounting for more than 90%of all oral cancers,and is characterized by high invasiveness and poor long-term prognosis.Its etiology is multifactorial,involving tobacco use,alcohol consumption,and human papillomavirus(HPV)infection.Oral leukoplakia and erythroplakia are the main precancerous lesions lesions,with oral leukoplakia being the most common.Both OSCC and premalignant lesions are closely associated with aberrant activation of multiple signaling pathways.Post-translational modifications(such as ubiquitination and deubiquitination)play key roles in regulating these pathways by controlling protein stability and activity.Growing evidence indicates that dysregulated ubiquitination/deubiquitination can mediate OSCC initiation and progression via aberrant activation of signaling pathways.The ubiquitination/deubiquitination process mainly involves E3 ligases(E3s)that catalyze substrate ubiquitination,deubiquitinating enzymes(DUBs)that remove ubiquitin chains,and the 26S proteasome complex that degrades ubiquitinated substrates.Abnormal expression or mutation of E3s and DUBs can lead to altered stability of critical tumorrelated proteins,thereby driving OSCC initiation and progression.Therefore,understanding the aberrantly activated signaling pathways in OSCC and the ubiquitination/deubiquitination mechanisms within these pathways will help elucidate the molecular mechanisms and improve OSCC treatment by targeting relevant components.Here,we summarize four aberrantly activated signaling pathways in OSCC―the PI3K/AKT/mTOR pathway,Wnt/β-catenin pathway,Hippo pathway,and canonical NF-κB pathway―and systematically review the regulatory mechanisms of ubiquitination/deubiquitination within these pathways,along with potential drug targets.PI3K/AKT/mTOR pathway is aberrantly activated in approximately 70%of OSCC cases.It is modulated by E3s(e.g.,FBXW7 and NEDD4)and DUBs(e.g.,USP7 and USP10):FBXW7 and USP10 inhibit signaling,while NEDD4 and USP7 potentiate it.Aberrant activation of the Wnt/β-catenin pathway leads toβ-catenin nuclear translocation and induction of cell proliferation.This pathway is modulated by E3s(e.g.,c-Cbl and RNF43)and DUBs(e.g.,USP9X and USP20):c-Cbl and RNF43 inhibit signaling,while USP9X and USP20 potentiate it.Hippo pathway inactivation permits YAP/TAZ to enter the nucleus and promotes cancer cell metastasis.This pathway is modulated by E3s(e.g.,CRL4^(DCAF1) and SIAH2)and DUBs(e.g.,USP1 and USP21):CRL4^(DCAF1) and SIAH2 inhibit signaling,while USP1 and USP21 potentiate it.Persistent activation of the canonical NF-κB pathway is associated with an inflammatory microenvironment and chemotherapy resistance.This pathway is modulated by E3s(e.g.,TRAF6 and LUBAC)and DUBs(e.g.,A20 and CYLD):A20 and CYLD inhibit signaling,while TRAF6 and LUBAC potentiate it.Targeting these E3s and DUBs provides directions for OSCC drug research.Small-molecule inhibitors such as YCH2823(a USP7 inhibitor),GSK2643943A(a USP20 inhibitor),and HOIPIN-8(a LUBAC inhibitor)have shown promising antitumor activity in preclinical models;PROTAC molecules,by binding to surface sites of target proteins and recruiting E3s,achieve targeted ubiquitination and degradation of proteins insensitive to small-molecule inhibitors,for example,PU7-1-mediated USP7 degradation,offering new strategies to overcome traditional drug limitations.Currently,NX-1607(a Cbl-b inhibitor)has entered phase I clinical trials,with preliminary results confirming its safety and antitumor activity.Future research on aberrant E3s and DUBs in OSCC and the development of highly specific inhibitors will be of great significance for OSCC precision therapy.
基金Supported by Key Project of Anhui Provincial Education Department,No.2022AH050486and 2021 High-level Talent Introduction Scientific Project of Anhui University of Chinese Medicine,No.2022rczd005.
文摘BACKGROUND Diabetes has a substantial impact on public health,highlighting the need for novel treatments.Ubiquitination,an intracellular protein modification process,is emerging as a promising strategy for regulating pathological mechanisms.We hypothesize that ubiquitination plays a critical role in the development and progression of diabetes and its complications,and that understanding these mechanisms can lead to new therapeutic approaches.AIM To uncover the research trends and advances in diabetes ubiquitination and its complications,we conducted a bibliometric analysis.METHODS Studies on ubiquitination in diabetes mellitus and its complications were retrieved from the Web of Science Core Collection.Visual mapping analysis was conducted using the CiteSpace software.RESULTS We gathered 791 articles published over the past 23 years,focusing on ubiquitination in diabetes and its associated complications.These articles originated from 54 countries and 386 institutions,with China as the leading contributor.Shanghai Jiao Tong University has the highest number of publications in this field.The most prominent authors contributing to this research area include Wei-Hua Zhang,with Zhang Y being the most frequently cited author.Additionally,The Journal of Biological Chemistry is noted as the most cited in this field.The predominant keywords included expression,activation,oxidative stress,phosphorylation,ubiquitination,degradation,and insulin resistance.CONCLUSION The role of ubiquitination in diabetes and its complications,such as diabetic nephropathy and cardiomyopathy,is a key research focus.However,these areas require further investigations.
文摘During the process of organizing our original data,we unfortunately identified two error in the figures within our published article.In Fig.1,the online version incorrectly labels the SNI+NAC group as the sham+NAC group.We have revised the grouping annotations in Fig.1 and have labeled the DHE staining in the figure to present the experimental design more clearly.
基金supported by the National Key Research and Development Program of China(2022YFE0203900,2024YFD2401101)China Agriculture Research System(CARS-46)+1 种基金National Natural Science Foundation of China(32473201)Guangdong S&T Program(2022B1111030001,2024B1212040007)。
文摘Ring finger protein 122(RNF122),an E3 ubiquitin ligase,orchestrates antiviral immune responses in mammals by targeting retinoic acid-inducible gene 1 and melanoma differentiation-associated gene 5 for ubiquitination.However,its functional relevance in teleosts has yet to be clearly defined,particularly regarding the identification of substrate-specific regulatory sites.This study characterized RNF122 from mandarin fish(Siniperca chuatsi),termed scRNF122,and investigated its regulatory impact on stimulator of interferon genes(STING)-mediated antiviral signaling.Results showed that scRNF122 expression was up-regulated in response to mandarin fish ranavirus(MRV)infection,and its overexpression suppressed scSTING-mediated interferon(IFN)production and enhanced MRV replication.Co-immunoprecipitation confirmed a direct interaction between scRNF122 and scSTING.Functional assays demonstrated that scRNF122 facilitated scSTING degradation through the ubiquitin-proteasome pathway,a process impeded by MG132 treatment.Ubiquitination analyses of various scSTING mutants revealed that scRNF122 catalyzed scSTING ubiquitination at K95,K117,and K155 residues.Moreover,scRNF122 significantly impaired scSTING-dependent antiviral responses by engaging negative regulatory elements within the signaling cascade.Overall,scRNF122 was identified as a negative modulator of STING-mediated IFN signaling in mandarin fish,diminishing STING-dependent antiviral activity and promoting its degradation via the ubiquitin-proteasome pathway at lysine residues K95,K117,and K155.These findings provide mechanistic insight into the post-translational control of STING in teleosts and establish a foundation for future investigations into antiviral immune regulation.
基金Co-first authors:Yu-Xing Tang 0000-0003-4382-4942Co-first authors:Wei-Zi Wu+8 种基金Corresponding author:Gang Chen,MD,Professor,Department of Pathology,The First Affiliated Hospital of Guangxi Medical University,No.6 Shuangyong Road,Nanning 530021,Guangxi Zhuang Autonomous Region,China.chengang@gxmu.edu.cn,0000-0003-2402-2987Co-corresponding authors:Yan-Ting ZhanSheng-Sheng Zhou,0000-0003-2414-460XDa-Tong Zeng,0000-0002-3338-4122Guang-Cai Zheng,0009-0001-5921-6688Rong-Quan He,0000-0002-7752-2080Di-Yuan Qin,0009-0003-3214-4762Wan-Ying Huang,0000-0002-8314-5963Yu-Lu Tang,0009-0004-0462-618X。
文摘BACKGROUND ANAPC1,a key regulator of the ubiquitination in tumour development,has not been thoroughly studied in hepatocellular carcinoma(HCC).AIM To elucidate the expression of ANAPC1 in HCC and its potential regulatory mechanism related to ubiquitination.METHODS Bulk RNA(RNA sequencing and microarrays),immunohistochemistry(IHC)tissues,and single-cell RNA sequencing(scRNA-seq)data were integrated to comprehensively investigate ANAPC1 expression in HCC.Clustered regularly interspaced short palindromic repeats analysis was performed to assess growth in HCC cell lines following ANAPC1 knockout.Enrichment analyses were conducted to explore the functions of ANAPC1.ScRNA-seq data was used to examine the cell cycle and metabolic levels.CellChat analysis was applied to investigate the interactions between ANAPC1 and different cell types.The relationship between ANAPC1 expression and drug concentration was analyzed.RESULTS ANAPC1 messenger RNA was found to be upregulated in bulk RNA,IHC tissues samples and malignant hepatocytes.The proliferation of JHH2 cell lines was most significantly inhibited after ANAPC1 knockdown.In biological pathways,the development of HCC was found to be linked to the regulation of ubiquitin-mediated proteolysis.Additionally,scRNA-seq results indicated that highly expressed ANAPC1 was in the G2/M phase,with increased glycolysis/gluconeogenesis activity.A CellChat analysis showed that ANAPC1 was associated with the regulation of the migration inhibitory factor-(cluster of differentiation 74+C-X-C chemokine receptor type 4)pathway.Higher ANAPC1 expression correlated with stronger effects of sorafenib,dasatinib,ibrutinib,lapatinib,nilotinib and afatinib.CONCLUSION The high expression level of ANAPC1 may regulate the cell cycle and metabolic levels of HCC through the ubiquitination-related pathway,thereby promoting disease progression.
基金supported by grants from the National Natural Science Foundation of China(Grant Nos.82172653 and 82472728)the Key Project of Developmental Biology and Breeding from Hunan Province(Grant No.2022XKQ0205)+1 种基金the Research Team for Reproduction Health and Translational Medicine of Hunan Normal University(Grant No.2023JC101)the Natural Science Foundation of Hunan Province(Grant No.2025JJ80150).
文摘Objective:Osimertinib(OSI)therapy,a cornerstone in treating non-small cell lung cancer(NSCLC),has been severely limited by rapidly developing acquired resistance.Inhibition of bypass activation using a combination strategy holds promise in overcoming this resistance.Biguanides,with excellent anti-tumor effects,have recently attracted much attention for this potential.The current study investigated whether novel biguanide compounds developed by our team could overcome OSI resistance and the underlying mechanisms were explored.Methods:A comprehensive screening assay using OSI-resistant cells identified the optimal combination of biguanide compounds with OSI.Proteomics,co-immunoprecipitation mass spectrometry,RNA sequencing,and homologous recombination assays were used to elucidate the molecular mechanisms underlying combination therapy.NSCLC tumor tissues,especially OSI-resistant tissues,obtained from our clinic were used to assess the correlations between key proteins and OSI resistance.Results:SMK-010,a highly potent biguanide compound,effectively overcame OSI resistance in vitro and in vivo.Mechanistical studies showed that BMI1/FGFR1 pathway activation is responsible for OSI resistance.Specifically,silencing BMI1 promoted NEDD4-mediated FGFR1 ubiquitination and proteasomal degradation,whereas SMK-010 treatment induced FGFR1 lysosomal degradation.This reduction in FGFR1 levels impaired homologous recombination,increased DNA damage,and surmounted OSI resistance.Analysis of clinical samples revealed overexpression of BMI1 and FGFR1 in NSCLC tissues and represented potential biomarkers for OSI resistance.Conclusions:These findings highlight the crucial role of the BMI1/FGFR1 axis in OSI resistance and provide a rational basis for the future clinical application of the biguanide,SMK-010,in combination with OSI.
基金supported by the Innovation Team and Talents Cultivation Program of National Administration of Traditional Chinese Medicine(No.ZYYCXTD-C-202208)2021 Shanghai Science and Technology Innovation Action Plan—Medical Innovation Research Project(No.31801153)the National Natural Youth Science Foundation of China(No.21MC1930500)。
文摘Objective:Gastric cancer(GC)is one of the most common malignancies seen in clinic and requires novel treatment options.Morin is a natural flavonoid extracted from the flower stalk of a highly valuable medicinal plant Prunella vulgaris L.,which exhibits an anti-cancer effect in multiple types of tumors.However,the therapeutic effect and underlying mechanism of morin in treating GC remains elusive.The study aims to explore the therapeutic effect and underlying molecular mechanisms of morin in GC.Methods:For in vitro experiments,the proliferation inhibition of morin was measured by cell counting kit-8 assay and colony formation assay in human GC cell line MKN45,human gastric adenocarcinoma cell line AGS,and human gastric epithelial cell line GES-1;for apoptosis analysis,microscopic photography,Western blotting,ubiquitination analysis,quantitative polymerase chain reaction analysis,flow cytometry,and RNA interference technology were employed.For in vivo studies,immunohistochemistry,biomedical analysis,and Western blotting were used to assess the efficacy and safety of morin in a xenograft mouse model of GC.Results:Morin significantly inhibited the proliferation of GC cells MKN45 and AGS in a dose-and timedependent manner,but did not inhibit human gastric epithelial cells GES-1.Only the caspase inhibitor Z-VAD-FMK was able to significantly reverse the inhibition of proliferation by morin in both GC cells,suggesting that apoptosis was the main type of cell death during the treatment.Morin induced intrinsic apoptosis in a dose-dependent manner in GC cells,which mainly relied on B cell leukemia/lymphoma 2(BCL-2)associated agonist of cell death(BAD)but not phorbol-12-myristate-13-acetate-induced protein 1.The upregulation of BAD by morin was due to blocking the ubiquitination degradation of BAD,rather than the transcription regulation and the phosphorylation of BAD.Furthermore,the combination of morin and BCL-2 inhibitor navitoclax(also known as ABT-737)produced a synergistic inhibitory effect in GC cells through amplifying apoptotic signals.In addition,morin treatment significantly suppressed the growth of GC in vivo by upregulating BAD and the subsequent activation of its downstream apoptosis pathway.Conclusion:Morin suppressed GC by inducing apoptosis,which was mainly due to blocking the ubiquitination-based degradation of the pro-apoptotic protein BAD.The combination of morin and the BCL-2 inhibitor ABT-737 synergistically amplified apoptotic signals in GC cells,which may overcome the drug resistance of the BCL-2 inhibitor.These findings indicated that morin was a potent and promising agent for GC treatment.
文摘3-Hydroxy-3-methylglutaryl coenzyme A （HMG CoA） reductase produces mevalonate, an important intermediate in the synthesis of cholesterol and essential nonsterol isoprenoids. The reductase is subject to an exorbitant amount of feedback control through multiple mechanisms that are mediated by sterol and nonsterol end-products of mevalonate metabolism. Here, I will discuss recent advances that shed light on one mechanism for control of reductase, which involves rapid degradation of the enzyme. Accumulation of certain sterols triggers binding of reductase to endoplasmic reticulum （ER） membrane proteins called Insig-1 and Insig-2. Reductase-Insig binding results in recruitment of a membrane-associated ubiquitin ligase called gp78, which initiates ubiquitination of reductase. This ubiquitination is an obligatory reaction for recognition and degradation of reductase from ER membranes by cytosolic 26S proteasomes. Thus, sterol-accelerated degradation of reductase represents an example of how a general cellular process （ER-associated degradation） is used to control an important metabolic pathway （cholesterol synthesis）.
文摘Post-translational modification is central to protein stability and to the modulation of protein activity. Various types of protein modification, such as phosphorylation, methylation, acetylation, myristoylation, glycosylation, and ubiquitination, have been reported. Among them, ubiquitination distinguishes itself from others in that most of the ubiquitinated proteins are targeted to the 26S proteasome for degradation. The ubiquitin/26S proteasome system constitutes the major protein degradation pathway in the cell. In recent years, the importance of the ubiquitination machinery in the control of numerous eukaryotic cellular functions has been increasingly appreciated. Increasing number of E3 ubiquitin ligases and their substrates, including a variety of essential cellular regulators have been identified. Studies in the past several years have revealed that the ubiquitination system is important for a broad range of plant developmental processes and responses to abiotic and biotic stresses. This review discusses recent advances in the functional analysis of ubiquitination-associated proteins from plants and pathogens that play important roles in plant-microbe interactions.
文摘DI-3-n-butylphthalide is used to treat mild and moderate acute ischemic stroke.However,the precise underlying mechanism requires further investigation.In this study,we investigated the molecular mechanism of DI-3-n-butylphthalide action by various means.We used hydrogen peroxide to induce injury to PC12cells and RAW264.7 cells to mimic neuronal oxidative stress injury in stroke in vitro and examined the effects of DI-3-n-butylphthalide.We found that DI-3-nbutylphthalide pretreatment markedly inhibited the reduction in viability and reactive oxygen species production in PC12 cells caused by hydrogen peroxide and inhibited cell apoptosis.Furthermore,DI-3-n-butylphthalide pretreatment inhibited the expression of the pro-apoptotic genes Bax and Bnip3.DI-3-nbutylphthalide also promoted ubiquitination and degradation of hypoxia inducible factor 1α,the key transcription factor that regulates Bax and Bnip3 genes.These findings suggest that DI-3-n-butylphthalide exhibits a neuroprotective effect on stroke by promoting hypoxia inducible factor-1α ubiquitination and degradation and inhibiting cell apoptosis.
基金the National Natural Science Foundation of China(Nos.81973524 and 81703754)the 111 Project from Ministry of Education of China and the State Administration of Foreign Export Affairs of China(B18056)+2 种基金the Drug Innovation Major Project(Nos.2018ZX09711-001-007and 2018ZX09735002-003)the“Double First-Class”University Project(CPU2018GF03)the special funds for Science and Technology Development under the Guidance of the Central Government(ZY20198020)。
文摘Polyphyllin I(PPI)purified from Polyphylla rhizomes displays puissant cytotoxicity in many kinds of cancers.Several researches investigated its anti-cancer activity.But novel mechanisms are still worth investigation.This study aimed to explore PPI-induced endoplasmic reticulum(ER)stress as well as the underlying mechanism in non-small cell lung cancer(NSCLC).Cell viability or colony-forming was detected by MTT or crystal violet respectively.Cell cycle,apoptosis,reactive oxygen species(ROS)and mitochondrial membrane potential were assessed by flow cytometry.Gene and protein levels were evaluated by q RT-PCR and immunoblotting respectively.Protein interaction was determined by immunoprecipitation or immunofluorescence assay.Gene overexpression or silencing was carried out by transient transfection with plasmids or small interfering RNAs.The Cancer Genome Atlas(TCGA)database was used for Gene Set Enrichment Analysis(GSEA),survival analysis,gene expression statistics or pathway enrichment assay.PPI inhibited the propagation of NSCLC cells,increased non-viable apoptotic cells,arrested cell cycle at G2/M phase,induced ROS levels but failed to decrease mitochondrial membrane potential.High levels of GRP78 indicates poor prognosis in NSCLC patients.PPI selectively suppressed unfolded protein response(UPR)-induced GRP78 expression,subsequently protected CHOP from GRP78-mediated ubiquitination and degradation.We demonstrated that the natural product PPI,obtained from traditional herbal medicine,deserves for further study as a valuable candidate for lead compound in the chemotherapy of NSCLC.
基金This study was supported by grants from the National Natural Science Foundation of China(81873592)the graduate tutor team construction project of Chongqing Municipal Education Commission Foundation(dstd201801).
文摘Background:NOD-like receptor family CARD domain containing 3(NLRC3)plays an important role in both innate and adaptive immunity.This study was to explore the function and related mechanisms of NLRC3 in a hypoxia/reoxygenation(H/R)-induced inflammatory response in RAW264.7 cells.Methods:Liver ischemia-reperfusion(I/R)model in mice and H/R model in RAW264.7 cells were constructed.Western blotting was used to determine the protein expression level of NLRC3 in liver tissue and NLRC3,TRAF6,p–p65,p65,IκB–α,and the K63-linked ubiquitination level of TRAF6 in cells.The immunofluorescence assay was performed to evaluate the nuclear level of the NF–κB(p65).ELISA was conducted to measure the content of IL–1βin serum and cell supernatant.The interaction between NLRC3 and TRAF6 in cells was analyzed by the Co-IP assay.Results:The NLRC3 protein level in liver tissue was decreased with the prolongation of reperfusion time(P<0.05).The expression of NLRC3 and IκB–αprotein in RAW264.7 was decreased gradually,while the expression of p–p65 and TRAF6 proteins and K63-linked ubiquitination of TRAF6 were increased gradually with the prolongation of reoxgenation time(P<0.05).The Co-IP assay revealed that NLRC3 and TRAF6 can bind to each other directly.However,NLRC3 had no effect on the expression of TRAF6 protein.The ubiquitination test results showed that the K63-linked ubiquitination level of TRAF6 in H/R+Lv–NLRC3 group was significantly lower than that in the H/R+negative control(NC)group(P<0.05).Moreover,the activation of NF–κB in H/R+Lv–NLRC3 group was inhibited compared with that in the H/R+NC group,and the level of the inflammatory factor IL–1βin the cell culture supernatant was also decreased accordingly(P<0.05).Conclusions:NLRC3 might alleviate H/R-induced inflammation in RAW264.7 cells by inhibiting K63-linked ubiquitination of TRAF6.
基金We thank Dr Richard Baer （Pathology, Columbia University, New York, USA） for generously providing various Ub mutant plasmids. This study was supported by Grants from the National Natural Science Foundation of China （30871257, 30730051） and the National High Technology Research, Development Program of China （2006CB943901 and 2007CB947904）, the Shanghai Sci- ence and Technology Developmental Foundation （08JC1413100） and the Shanghai Leading Academic Discipline Project （$30201）.
文摘Transcription factor Oct4 plays critical roles in maintaining pluripotency and controlling lineage commitment of embryonic stem cells （ESCs）. Our previous study indicates that Wwp2, a mouse HECT-type E3 ubiquitin ligase, ubiquitinates Oct4 and promotes its degradation in a heterologous system. However, roles of Wwp2 in regulating en- dogenous Oct4 protein levels as well as molecular characteristics of the function of Wwp2 have not been determined. Here, we report that Wwp2 plays an important role in Oct4 ubiquitination and degradation during differentiation of embryonal carcinoma cells （ECCs）, although it does not appear to affect Oct4 protein levels in the undifferentiated ECCs and ESCs. Importantly, inhibition of Wwp2 expression by specific RNA interference elevates the Oct4 protein level, leading to attenuation in retinoid acid-induced activation of differentiation-related marker genes. Mechanisti- cally, Wwp2 catalyzes Oct4 poly-ubiquitination via the lysine 63 linkage in a dosage-dependent manner. Interest- ingly, Wwp2 also regulates its own ligase activity in a similar manner. Moreover, auto-ubiquitination of Wwp2 occurs through an intra-molecular mechanism. Taken together, these results demonstrate a crucial role of Wwp2 in con- trolling endogenous Oct4 protein levels during differentiation processes of ECCs and suggest an interesting dosage- dependent mechanism for regulating the catalytic activity of the E3 ubiquitin ligase, Wwp2.
基金supported by grants from the National Natural Science Foundation of China (31630079,31672531,31572526,and 31802164)the National Key R&D Program of China (2016YFD0500206,2015BAD11B02)+3 种基金the Strategic Priority Research Program of Chinese Academy of Sciences (XDB29010000)the National Science and Technology Major Project (2018ZX10101004)the Emergency Technology Research Issue on Prevention and Control for Human Infection with A (H7N9) Avian Influenza Virus (10600100000015001206)Wenjun Liu is the principal investigator of the Innovative Research Group of National Natural Science Foundation of China (Grant No.81621091)
文摘Cyclophilin A (CypA) is a peptidyl-prolyl cis/trans isomerase that interacts with the matrix protein (M1) of influenza A virus (IAV) and restricts virus replication by regulating the ubiquitin–proteasome-mediated degradation of M1. However,the mechanism by which CypA regulates M1 ubiquitination remains unknown. In this study, we reported that E3 ubiquitin ligase AIP4 promoted K48-linked ubiquitination of M1 at K102 and K104, and accelerated ubiquitin–proteasome-mediated degradation of M1. The recombinant IAV with mutant M1 (K102 R/K104 R) could not be rescued, suggesting that the ubiquitination of M1 at K102/K104 was essential for IAV replication. Furthermore, CypA inhibited AIP4-mediated M1 ubiquitination by impairing the interaction between AIP4 and M1. More importantly, both the mutations of M1 (K102 R/K104 R) and CypA inhibited the nuclear export of M1, indicating that CypA regulates the cellular localization of M1 via inhibition of AIP4-mediated M1 ubiquitination at K102 and K104, which results in the reduced replication of IAV.Collectively, our findings reveal a novel ubiquitination-based mechanism by which CypA regulates the replication of IAV.
基金was supported by the National Natural Sciences Foundation of China(No.30470379).
文摘Fanconi anemia(FA)is a rare recessive hereditary disease characterized clinically by congenital defects,progressive bone-marrow failure,and cancer predisposition.Cells from FA patients exhibit hypersensitivity to DNA cross-linking agents,such as mitomycin C(MMC).To date,at least 12 FA genes have been found deleted or mutated in FA cells,and 10 FA gene products form a core complex involved in FA/BRCA2 DNA repair pathway-FA pathway.The ubiquitin E3 ligase FANCL,an important factor of FA core complex,co-functions with a new ubiquitin conjugating enzyme UBE2T to catalyze the monoubiquitination of FANCD2.FANCD2-Ub binds BRCA2 to form a new complex located in chromatin foci and then take part in DNA repair process.The deubiquitylating enzyme USP1 removes the mono-ubiquitin from FANCD2-Ub following completion of the repair process,then restores the blocked cell cycle to normal order by shutting off the FA pathway.In a word,the FANCD2 activity adjusted exquisitely by ubiquitination and/or deubiquitination in vivo may co-regulate the FA pathway involving in variant DNA repair pathway.
基金provided by Funding of State Key Laboratory of Oral Disease (Sichuan University, SKLOD201702)the National Science Foundation for Excellent Young Scholars of China (81322013)+1 种基金the Innovation Team of Sichuan Province (2015TD0011)Start-up Funding from State Key Laboratory of Oral Disease, West China School of Stomatology, Sichuan University, China (To Peng Liu)
文摘The adaptor protein NUMB is involved in asymmetric division and cell fate determination and recognized as an antagonist of Notch.Previous studies have proved that Notch activation in osteoblasts contributes to a high bone mass. In this study, however, an osteopenic phenotype was found in 9-week-old mice using osteoblastic specific Col1a1–2.3-Cre to ablate both Numb and its homologue Numbl. The trabecular bone mass decreased dramatically while the cortical bone mass was unaffected. Here, the Notch signal was not activated,while the tensin homologue deleted on human chromosome 10(PTEN), which dephosphorylates phosphatidylinositide 3-kinases, was elevated, attenuating protein kinase B(Akt). The ubiquitination assay revealed that NUMB may physiologically promote PTEN ubiquitination in the presence of neural precursor cell-expressed developmentally downregulated protein 4–1. In addition, the deficiency of Numb/Numbl also activated the Hedgehog pathway through GLI1. This process was found to improve the ratio of the receptor activator of nuclear factor-k B ligand to osteoprotegerin, which enhanced the differentiation of osteoclasts and bone resorption. In conclusion, this study provides an insight into new functons of NUMB and NUMBL on bone homeostasis.
基金supported by grants from the National Natural Science Foundation of China(Grant Nos.:82122043,81972052,81902213,82201537,and 81730065)the China Postdoctoral Science Foundation(Grant Nos.:2021M693946 and 2019M653967).
文摘A major impedance to neuronal regeneration after peripheral nerve injury (PNI) is the activation of various programmed cell death mechanisms in the dorsal root ganglion. Ferroptosis is a form of programmed cell death distinguished by imbalance in iron and thiol metabolism, leading to lethal lipid peroxidation. However, the molecular mechanisms of ferroptosis in the context of PNI and nerve regeneration remain unclear. Ferroportin (Fpn), the only known mammalian nonheme iron export protein, plays a pivotal part in inhibiting ferroptosis by maintaining intracellular iron homeostasis. Here, we explored in vitro and in vivo the involvement of Fpn in neuronal ferroptosis. We first delineated that reactive oxygen species at the injury site induces neuronal ferroptosis by increasing intracellular iron via accelerated UBA52-driven ubiquitination and degradation of Fpn, and stimulation of lipid peroxidation. Early administration of the potent arterial vasodilator, hydralazine (HYD), decreases the ubiquitination of Fpn after PNI by binding to UBA52, leading to suppression of neuronal cell death and significant acceleration of axon regeneration and motor function recovery. HYD targeting of ferroptosis is a promising strategy for clinical management of PNI.
基金the Science and Technology Development Fund,Macao SAR(Grant Nos.:No.0159/2020/A3,No.0058/2020/AMJ,No.0096/2019/A2 and SKL-QRCM(UM)-2023-2025)the Research Committee of the University of Macao(Grant No.:MYRG2022-00189-ICMS)+2 种基金the Guangdong Provincial Special Fund for Marine Economic Development Project(Project No.:GDNRC[2021]48)National Natural Science Foundation of China(Grant No.:82260801)K.C.Wong Education Foundation(Grant No.:GJTD-2020-12).
文摘Activation of nuclear factor erythroid 2-related factor 2(Nrf2)by Kelch-like ECH-associated protein 1(Keap1)alkylation plays a central role in anti-inflammatory therapy.However,activators of Nrf2 through alkylation of Keap1-Kelch domain have not been identified.Deoxynyboquinone(DNQ)is a natural small molecule discovered from marine actinomycetes.The current study was designed to investigate the anti-inflammatory effects and molecular mechanisms of DNQ via alkylation of Keap1.DNQ exhibited significant anti-inflammatory properties both in vitro and in vivo.The pharmacophore responsible for the anti-inflammatory properties of DNQ was determined to be theα,β-unsaturated amides moieties by a chemical reaction between DNQ and N-acetylcysteine.DNQ exerted anti-inflammatory effects through activation of Nrf2/ARE pathway.Keap1 was demonstrated to be the direct target of DNQ and bound with DNQ through conjugate addition reaction involving alkylation.The specific alkylation site of DNQ on Keap1 for Nrf2 activation was elucidated with a synthesized probe in conjunction with liquid chromatography-tandem mass spectrometry.DNQ triggered the ubiquitination and subsequent degradation of Keap1 by alkylation of the cysteine residue 489(Cys489)on Keap1-Kelch domain,ultimately enabling the activation of Nrf2.Our findings revealed that DNQ exhibited potent anti-inflammatory capacity throughα,β-unsaturated amides moieties active group which specifically activated Nrf2 signal pathway via alkylation/ubiquitination of Keap1-Kelch domain,suggesting the potential values of targeting Cys489 on Keap1-Kelch domain by DNQ-like small molecules in inflammatory therapies.
基金National Natural Science Foundation of China(Grant Nos.81971502,82060298,31570876).
文摘TANK-binding kinase 1(TBK1)is a nodal protein involved in multiple signal transduction pathways.In RNA virus-mediated innate immunity,TBK1 is recruited to the prion-like platform formed by MAVS and subsequently activates the transcription factors IRF3/7 and NF-κB to produce type I interferon(IFN)and proinflammatory cytokines for the signaling cascade.In this study,TRAF7 was identified as a negative regulator of innate immune signaling.TRAF7 interacts with TBK1 and promotes K48-linked polyubiquitination and degradation of TBK1 through its RING domain,impairing the activation of IRF3 and the production of IFN-β.In addition,we found that the conserved cysteine residues at position 131 of TRAF7 are necessary for its function toward TBK1.Knockout of TRAF7 could facilitate the activation of IRF3 and increase the transcript levels of downstream antiviral genes.These data suggest that TRAF7 negatively regulates innate antiviral immunity by promoting the K48-linked ubiquitination of TBK1.
