Conserved dopamine neurotrophic factor protects and rescues dopaminergic neurodegeneration induced by 6-hydroxydopamine in vivo,but its potential value in treating Parkinson＇s disease remains controversial.Here,we us...Conserved dopamine neurotrophic factor protects and rescues dopaminergic neurodegeneration induced by 6-hydroxydopamine in vivo,but its potential value in treating Parkinson＇s disease remains controversial.Here,we used the proteasome inhibitors lactacystin and MG132 to induce neurodegeneration of PC12 cells.Afterwards,conserved dopamine neurotrophic factor was administrated as a therapeutic factor,both pretreatment and posttreatment.Our results showed that（1）conserved dopamine neurotrophic factor enhanced lactacystin/MG132-induced cell viability and morphology,and attenuated alpha-synuclein accumulation in differentiated PC12 cells.（2）Enzyme linked immunosorbent assay showed up-regulated 26S proteasomal activity in MG132-induced PC12 cells after pre-and posttreatment with conserved dopamine neurotrophic factor.Similarly,26S proteasome activity was upregulated in lactacystin-induced PC12 cells pretreated with conserved dopamine neurotrophic factor.（3）With regard proteolytic enzymes（specifically,glutamyl peptide hydrolase,chymotrypsin,and trypsin）,glutamyl peptide hydrolase activity was up-regulated in lactacystin/MG132-administered PC12 cells after pre-and posttreatment with conserved dopamine neurotrophic factor.However,upregulation of chymotrypsin activity was only observed in MG132-administered PC12 cells pretreated with conserved dopamine neurotrophic factor.There was no change in trypsin expression.We conclude that conserved dopamine neurotrophic factor develops its neurotrophic effects by modulating proteasomal activities,and thereby protects and rescues PC12 cells against neurodegeneration.展开更多
Studies on rodents and humans demonstrate an inherited predisposition to hepatocellular carcinoma （HCC）. Analysis of the molecular alterations involved in the acquisition of a phenotype resistant or susceptible to h...Studies on rodents and humans demonstrate an inherited predisposition to hepatocellular carcinoma （HCC）. Analysis of the molecular alterations involved in the acquisition of a phenotype resistant or susceptible to hepatocarcinogenesis showed a deregulation of G1 and S phases in HCC of genetically susceptible F344 rats and a G1-S block in lesions of resistant Brown norway （BN） rats. Unrestrained extracellular signal-regulated kinase （ERK） activity linked to proteasomal degradation of dual-specificity phosphatase 1 （DUSP1）, a specific ERK inhibitor, by the CKS1-SKP2 ubiquitin ligase complex occurs in more aggressive HCC of F344 rats and humans. This mechanism is less active in HCC of BN rats and human HCC with better prognosis. Upregulation of iNos cross-talk with IKK/NF-KB and RAS/ERK pathways occurs in rodent liver lesions at higher levels in the most aggressive models represented by HCC of F344 rats and c-Myc-TGF-α transgenic mice. iNOS, IKK/NF-κB, and RAS/ERK upregulation is highest in human HCC with a poorer prognosis and positively correlates with tumor proliferation, genomic instability and microvascularization, and negatively with apoptosis. Thus, cell cycle regulation and the activity of signal transduction pathways seem to be modulated by HCC modifier genes, and differences in their efficiency influence the susceptibility to hepatocarcinogenesis and probably the prognosis of human HCC.展开更多
As a result of accumulating methylglyoxal and advanced glycation end products in the brains of patients with Alzheimer’s disease,it is considered a protein precipitation disease.The ubiquitin proteasome system is one...As a result of accumulating methylglyoxal and advanced glycation end products in the brains of patients with Alzheimer’s disease,it is considered a protein precipitation disease.The ubiquitin proteasome system is one of the most important mechanisms for cells to degrade proteins,and thus is very important for maintaining normal physiological function of the nervous system.This study recruited 48 individuals with Alzheimer’s disease(20 males and 28 females aged 75±6 years)and 50 healthy volunteers(21 males and 29 females aged 72±7 years)from the Affiliated Hospital of Youjiang Medical University for Nationalities(Baise,China)between 2014 and 2017.Plasma levels of malondialdehyde and H2O2 were measured by colorimetry,while glyoxalase 1 activity was detected by spectrophotometry.In addition,20S proteasome activity in erythrocytes was measured with a fluorescent substrate method.Ubiquitin and glyoxalase 1 protein expression in erythrocyte membranes was detected by western blot assay.The results demonstrated that compared with the control group,patients with Alzheimer’s disease exhibited increased plasma malondialdehyde and H2O2 levels,and decreased glyoxalase 1 activity;however,expression level of glyoxalase 1 protein remained unchanged.Moreover,activity of the 20S proteasome was decreased and expression of ubiquitin protein was increased in erythrocytes.These findings indicate that proteasomal and glyoxalase activities may be involved in the occurrence of Alzheimer’s disease,and erythrocytes may be a suitable tissue for Alzheimer’s disease studies.This study was approved by the Ethics Committee of Youjiang Medical University for Nationalities(approval No.YJ12017013)on May 3,2017.展开更多
Pregnane X receptor(PXR)is a ligand-activated nuclear receptor that transcriptionally upregulates drug-metabolizing enzymes[e.g.,cytochrome P4503A4(CYP3A4)]and transporters.Although the regulation of PXR target genes ...Pregnane X receptor(PXR)is a ligand-activated nuclear receptor that transcriptionally upregulates drug-metabolizing enzymes[e.g.,cytochrome P4503A4(CYP3A4)]and transporters.Although the regulation of PXR target genes is well-characterized,less is known about the regulation of PXR protein level.By screening an RNAi library,we identified the F-box-only protein 44(FBXO44)as a novel E3ligase for PXR.PXR abundance increases upon knockdown of FBXO44,and,inversely,decreases upon overexpression of FBXO44.Further analysis revealed that FBXO44 interacts with PXR,leading to its ubiquitination and proteasomal degradation,and we determined that the F-box associated domain of FBXO44 and the ligand binding domain of PXR are required for the functional interaction.In summary,FBXO44 regulates PXR protein abundance,which has downstream consequences for CYP3A4 levels and drug-drug interactions.The results of this study provide new insight into the molecular mechanisms that regulate PXR protein level and activity and suggest the importance of considering how modulating E3ubiquitin ligase activities will affect PXR-mediated drug metabolism.展开更多
Non-alcoholic fatty liver disease(NAFLD),characterized by hepatic steatosis,is one of the commonest causes of liver dysfunction.Adipose triglyceride lipase(ATGL)is closely related to lipid turnover and hepatic steatos...Non-alcoholic fatty liver disease(NAFLD),characterized by hepatic steatosis,is one of the commonest causes of liver dysfunction.Adipose triglyceride lipase(ATGL)is closely related to lipid turnover and hepatic steatosis as the speed-limited triacylglycerol lipase in liver lipolysis.However,the expression and regulation of ATGL in NAFLD remain unclear.Herein,our results showed that ATGL protein levels were decreased in the liver tissues of high-fat diet(HFD)-fed mice,naturally obese mice,and cholangioma/hepatic carcinoma patients with hepatic steatosis,as well as in the oleic acid-induced hepatic steatosis cell model,while ATGL mRNA levels were not changed.ATGL protein was mainly degraded through the proteasome pathway in hepatocytes.Beta-transducin repeat containing(BTRC)was upregulated and negatively correlated with the decreased ATGL level in these hepatic steatosis models.Consequently,BTRC was identified as the E3 ligase for ATGL through predominant ubiquitination at the lysine 135 residue.Moreover,adenovirus-mediated knockdown of BTRC ameliorated steatosis in HFD-fed mouse livers and oleic acid-treated liver cells via upregulating the ATGL level.Taken together,BTRC plays a crucial role in hepatic steatosis as a new ATGL E3 ligase and may serve as a potential therapeutic target for treating NAFLD.展开更多
The NS5A non-structural protein of classical swine fever virus(CSFV)is a multifunctional protein involved in viral genomic replication,protein translation,assembly of infectious virus particles,and regulation of cellu...The NS5A non-structural protein of classical swine fever virus(CSFV)is a multifunctional protein involved in viral genomic replication,protein translation,assembly of infectious virus particles,and regulation of cellular signaling pathways.Previous report showed that NS5A inhibited nuclear factor kappa B(NF-κB)signaling induced by poly(I:C);however,the mechanism involved has not been elucidated.Here,we reported that NS5A directly interacted with NF-κB essential modulator(NEMO),a regulatory subunit of the IκB kinase(IKK)complex,to inhibit the NF-κB signaling pathway.Further investigations showed that the zinc finger domain of NEMO and the aa 126–250 segment of NS5A are essential for the interaction between NEMO and NS5A.Mechanistic analysis revealed that NS5A mediated the proteasomal degradation of NEMO.Ubiquitination assay showed that NS5A induced the K27-linked but not the K48-linked polyubiquitination of NEMO for proteasomal degradation.In addition,NS5A blocked the K63-linked polyubiquitination of NEMO,thus inhibiting IKK phosphorylation,IκBαdegradation,and NF-κB activation.These findings revealed a novel mechanism by which CSFV inhibits host innate immunity,which might guide the drug design against CSFV in the future.展开更多
Background The mechanism of hepatitis B virus(HBV)-induced carcinogenesis remains an area of interest.The accumulation of hepatitis B surface antigen in the endoplasmic reticulum(ER)of hepatocytes stimulates persisten...Background The mechanism of hepatitis B virus(HBV)-induced carcinogenesis remains an area of interest.The accumulation of hepatitis B surface antigen in the endoplasmic reticulum(ER)of hepatocytes stimulates persistent ER stress.Activity of the unfolded protein response(UPR)pathway of ER stress may play an important role in inflammatory cancer transformation.How the protective UPR pathway is hijacked by cells as a tool for malignant transformation in HBV-related hepatocellular carcinoma(HCC)is still unclear.Here,we aimed to define the key molecule hyaluronan-mediated motility receptor(HMMR)in this process and explore its role under ER stress in HCC development.Methods An HBV-transgenic mouse model was used to characterize the pathological changes during the tumor progression.Proteomics and transcriptomics analyses were performed to identify the potential key molecule,screen the E3 ligase,and define the activation pathway.Quantitative real-time PCR and Western blotting were conducted to detect the expression of genes in tissues and cell lines.Luciferase reporter assay,chromatin immunoprecipitation,coimmunoprecipitation,immunoprecipitation,and immunofluorescence were employed to investigate the molecular mechanisms of HMMR under ER stress.Immunohistochemistry was used to clarify the expression patterns of HMMR and related molecules in human tissues.Results We found sustained activation of ER stress in the HBV-transgenic mouse model of hepatitis-fibrosis-HCC.HMMR was transcribed by c/EBP homologous protein(CHOP)and degraded by tripartite motif containing 29(TRIM29)after ubiquitination under ER stress,which caused the inconsistent expression of mRNA and protein.Dynamic expression of TRIM29 in the HCC progression regulated the dynamic expression of HMMR.HMMR could alleviate ER stress by increasing autophagic lysosome activity.The negative correlation between HMMR and ER stress,positive correlation between HMMR and autophagy,and negative correlation between ER stress and autophagy were verified in human tissues.Conclus展开更多
Background:Age-related macular degeneration(AMD)is the leading cause of vision loss worldwide.However,the mechanisms involved in the development and progression of AMD are poorly delineated.We aimed to explore the cri...Background:Age-related macular degeneration(AMD)is the leading cause of vision loss worldwide.However,the mechanisms involved in the development and progression of AMD are poorly delineated.We aimed to explore the critical genes involved in the progression of AMD.Methods:The differentially expressed genes(DEGs)in AMD retinal pigment epithelial(RPE)/choroid tissues were identified using the microarray datasets GSE99248 and GSE125564,which were downloaded from the gene expression omnibus database.The overlapping DEGs from the two datasets were screened to identify DEG-related biological pathways using gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses.The hub genes were identified from these DEGs through protein-protein interaction network analyses.The expression levels of hub genes were evaluated by quantitative real-time polymerase chain reaction following the induction of senescence in ARPE-19 with FK866.Following the identification of AMD-related key genes,the potential small molecule compounds targeting the key genes were predicted by PharmacoDB.Finally,a microRNA-gene interaction network was constructed.Results:Microarray analyses identified 174 DEGs in the AMD RPE compared to the healthy RPE samples.These DEGs were primarily enriched in the pathways involved in the regulation of DNA replication,cell cycle,and proteasome-mediated protein polyubiquitination.Among the top ten hub genes,HSP90AA1,CHEK1,PSMA4,PSMD4,and PSMD8 were upregulated in the senescent ARPE-19 cells.Additionally,the drugs targeting HSP90AA1,CHEK1,and PSMA4 were identified.We hypothesize that Hsa-miR-16-5p might target four out of the five key DEGs in the AMD RPE.Conclusions:Based on our findings,HSP90AA1 is likely to be a central gene controlling the DNA replication and proteasome-mediated polyubiquitination during the RPE senescence observed in the progression of AMD.Targeting HSP90AA1,CHEK1,PSMA4,PSMD4,and/or PSMD8 genes through specific miRNAs or small molecules might potentially alleviate the progression of AMD展开更多
Inflammasomes are essential components of the innate immune system and its defense against infections,whereas the dysregulation of inflammasome activation has a detrimental effect on human health.The activation of inf...Inflammasomes are essential components of the innate immune system and its defense against infections,whereas the dysregulation of inflammasome activation has a detrimental effect on human health.The activation of inflammasomes is subjected to tight regulation to maintain immune homeostasis,yet the underlying mechanism remains elusive.Here,we identify USP3 as a direct deubiquitinating enzyme(DUB)for ASC,the central adapter mediating the assembly and activation of most inflammasomes.USP3 removes the K48-linked ubiquitination on ASC and strengthens its stability by blocking proteasomal degradation.Additionally,USP3 promotes inflammasome activation,and this function was confirmed in mouse models of aluminum(Alum)-induced peritonitis,F.novicida infection and flagellin-induced pneumonia in vivo.Our work unveils that USP3 functions as a key regulator of ASC ubiquitination and maintains the physiological role of ASC in mediating inflammasome activation,and we propose a new mechanism by which the ubiquitination of ASC regulates inflammasome activation.展开更多
Androgen receptor （AR） is able to promote stress-induced cell death independently of its transcription activity in androgen-independent prostate cancer cells. Yet, the underlying mechanism is incompletely understood...Androgen receptor （AR） is able to promote stress-induced cell death independently of its transcription activity in androgen-independent prostate cancer cells. Yet, the underlying mechanism is incompletely understood. Here, we report that stress-induced proteasomal degradation of AR contributes to its pro-death activity. Upon exposure to ul- traviolet fight and staurosporine, AR underwent proteasomal degradation. Blockade of AR degradation significantly suppressed stress-induced apoptosis in androgen-independent prostate cancer cells. Ectopic expression of the AR N-terminal （AR-N） domain, which lacks DNA- and ligand-binding abilities, led to cell death without any additional death stimuli. Truncation analysis revealed that AR-N domain contains several sub-domains that regulate the pro- death activity of AR, specifically the first 105 amino acids, which function as a minimal pro-death domain acting upstream of caspases. The pro-apoptotic activity of AR N-terminal fragments was suppressed by ectopic expression of Bcl-2 or selected caspase inhibitors. Thus, our results reveal a novel mechanism by which AR promotes stressinduced cell death in androgen-independent prostate cancer cells.展开更多
程序性死亡受体配体1(programmed death ligand 1,PD-L1)是肿瘤免疫检查点阻断治疗中的重要靶点,其在多种细胞中均有表达。肿瘤细胞可通过高表达PD-L1来增强程序性死亡受体1(programmed death 1,PD-1)抑制信号,从而促进肿瘤免疫逃逸。...程序性死亡受体配体1(programmed death ligand 1,PD-L1)是肿瘤免疫检查点阻断治疗中的重要靶点,其在多种细胞中均有表达。肿瘤细胞可通过高表达PD-L1来增强程序性死亡受体1(programmed death 1,PD-1)抑制信号,从而促进肿瘤免疫逃逸。近年来,以抗PD-1/PD-L1抗体为代表的肿瘤免疫治疗给癌症治疗带来了革命性的变化。然而,肿瘤免疫治疗仅能对部分患者产生持久的疗效,多数患者对肿瘤免疫治疗的应答短暂或没有应答。研究发现,PD-L1的降解对肿瘤免疫治疗应答至关重要。本文综述了PD-L1的溶酶体降解途径、蛋白酶体降解途径及PD-L1降解与肿瘤免疫治疗的相互作用,旨在为进一步增强肿瘤免疫治疗的应答率和应答范围提供研究思路。展开更多
基金supported by the Natural Science Foundation of Anhui Province of China,No.11040606Q11the National Natural Science Foundation of China,No.81100960
文摘Conserved dopamine neurotrophic factor protects and rescues dopaminergic neurodegeneration induced by 6-hydroxydopamine in vivo,but its potential value in treating Parkinson＇s disease remains controversial.Here,we used the proteasome inhibitors lactacystin and MG132 to induce neurodegeneration of PC12 cells.Afterwards,conserved dopamine neurotrophic factor was administrated as a therapeutic factor,both pretreatment and posttreatment.Our results showed that（1）conserved dopamine neurotrophic factor enhanced lactacystin/MG132-induced cell viability and morphology,and attenuated alpha-synuclein accumulation in differentiated PC12 cells.（2）Enzyme linked immunosorbent assay showed up-regulated 26S proteasomal activity in MG132-induced PC12 cells after pre-and posttreatment with conserved dopamine neurotrophic factor.Similarly,26S proteasome activity was upregulated in lactacystin-induced PC12 cells pretreated with conserved dopamine neurotrophic factor.（3）With regard proteolytic enzymes（specifically,glutamyl peptide hydrolase,chymotrypsin,and trypsin）,glutamyl peptide hydrolase activity was up-regulated in lactacystin/MG132-administered PC12 cells after pre-and posttreatment with conserved dopamine neurotrophic factor.However,upregulation of chymotrypsin activity was only observed in MG132-administered PC12 cells pretreated with conserved dopamine neurotrophic factor.There was no change in trypsin expression.We conclude that conserved dopamine neurotrophic factor develops its neurotrophic effects by modulating proteasomal activities,and thereby protects and rescues PC12 cells against neurodegeneration.
基金Supported by Grants from the"Associazione Italiana Ricerche sul Cancro"
文摘Studies on rodents and humans demonstrate an inherited predisposition to hepatocellular carcinoma （HCC）. Analysis of the molecular alterations involved in the acquisition of a phenotype resistant or susceptible to hepatocarcinogenesis showed a deregulation of G1 and S phases in HCC of genetically susceptible F344 rats and a G1-S block in lesions of resistant Brown norway （BN） rats. Unrestrained extracellular signal-regulated kinase （ERK） activity linked to proteasomal degradation of dual-specificity phosphatase 1 （DUSP1）, a specific ERK inhibitor, by the CKS1-SKP2 ubiquitin ligase complex occurs in more aggressive HCC of F344 rats and humans. This mechanism is less active in HCC of BN rats and human HCC with better prognosis. Upregulation of iNos cross-talk with IKK/NF-KB and RAS/ERK pathways occurs in rodent liver lesions at higher levels in the most aggressive models represented by HCC of F344 rats and c-Myc-TGF-α transgenic mice. iNOS, IKK/NF-κB, and RAS/ERK upregulation is highest in human HCC with a poorer prognosis and positively correlates with tumor proliferation, genomic instability and microvascularization, and negatively with apoptosis. Thus, cell cycle regulation and the activity of signal transduction pathways seem to be modulated by HCC modifier genes, and differences in their efficiency influence the susceptibility to hepatocarcinogenesis and probably the prognosis of human HCC.
基金supported by the National Natural Science Foundation of China,No.81860244the Natural Science Foundation of Guangxi Zhuang Autonomous Region of China,No.2018JJA140311 and 2018GXNSFAA281051the Basic Ability Enhancement Program for Young and Middle-aged Teachers of Guangxi Zhuang Autonomous Region of China,No.2017KY0516(all to CDJ)
文摘As a result of accumulating methylglyoxal and advanced glycation end products in the brains of patients with Alzheimer’s disease,it is considered a protein precipitation disease.The ubiquitin proteasome system is one of the most important mechanisms for cells to degrade proteins,and thus is very important for maintaining normal physiological function of the nervous system.This study recruited 48 individuals with Alzheimer’s disease(20 males and 28 females aged 75±6 years)and 50 healthy volunteers(21 males and 29 females aged 72±7 years)from the Affiliated Hospital of Youjiang Medical University for Nationalities(Baise,China)between 2014 and 2017.Plasma levels of malondialdehyde and H2O2 were measured by colorimetry,while glyoxalase 1 activity was detected by spectrophotometry.In addition,20S proteasome activity in erythrocytes was measured with a fluorescent substrate method.Ubiquitin and glyoxalase 1 protein expression in erythrocyte membranes was detected by western blot assay.The results demonstrated that compared with the control group,patients with Alzheimer’s disease exhibited increased plasma malondialdehyde and H2O2 levels,and decreased glyoxalase 1 activity;however,expression level of glyoxalase 1 protein remained unchanged.Moreover,activity of the 20S proteasome was decreased and expression of ubiquitin protein was increased in erythrocytes.These findings indicate that proteasomal and glyoxalase activities may be involved in the occurrence of Alzheimer’s disease,and erythrocytes may be a suitable tissue for Alzheimer’s disease studies.This study was approved by the Ethics Committee of Youjiang Medical University for Nationalities(approval No.YJ12017013)on May 3,2017.
基金supported by the National Institutes of Health National Institute of General Medical Sciences[Grant R35GM118041]supported in part by the National Cancer Institute of the National Institutes of Health under Award Number P30 CA021765。
文摘Pregnane X receptor(PXR)is a ligand-activated nuclear receptor that transcriptionally upregulates drug-metabolizing enzymes[e.g.,cytochrome P4503A4(CYP3A4)]and transporters.Although the regulation of PXR target genes is well-characterized,less is known about the regulation of PXR protein level.By screening an RNAi library,we identified the F-box-only protein 44(FBXO44)as a novel E3ligase for PXR.PXR abundance increases upon knockdown of FBXO44,and,inversely,decreases upon overexpression of FBXO44.Further analysis revealed that FBXO44 interacts with PXR,leading to its ubiquitination and proteasomal degradation,and we determined that the F-box associated domain of FBXO44 and the ligand binding domain of PXR are required for the functional interaction.In summary,FBXO44 regulates PXR protein abundance,which has downstream consequences for CYP3A4 levels and drug-drug interactions.The results of this study provide new insight into the molecular mechanisms that regulate PXR protein level and activity and suggest the importance of considering how modulating E3ubiquitin ligase activities will affect PXR-mediated drug metabolism.
基金supported by grants from the National Natural Science Foundation of China(82070888,82070882,82100917,82273116,82203661,81901557,and 81902693)the National Key R&D Program of China(2018YFA0800403)+3 种基金Guangdong Special Support Program for Young Top Scientist(201629046)Guangdong Natural Science Fund(2021A1515010434,2022A1515012423,2022A1515012513,and 2023A1515010316)the Key Sci-Tech Research Project of Guangzhou Municipality(202201010820)China Postdoctoral Science Foundation(2021M703679 and 2020M683110).
文摘Non-alcoholic fatty liver disease(NAFLD),characterized by hepatic steatosis,is one of the commonest causes of liver dysfunction.Adipose triglyceride lipase(ATGL)is closely related to lipid turnover and hepatic steatosis as the speed-limited triacylglycerol lipase in liver lipolysis.However,the expression and regulation of ATGL in NAFLD remain unclear.Herein,our results showed that ATGL protein levels were decreased in the liver tissues of high-fat diet(HFD)-fed mice,naturally obese mice,and cholangioma/hepatic carcinoma patients with hepatic steatosis,as well as in the oleic acid-induced hepatic steatosis cell model,while ATGL mRNA levels were not changed.ATGL protein was mainly degraded through the proteasome pathway in hepatocytes.Beta-transducin repeat containing(BTRC)was upregulated and negatively correlated with the decreased ATGL level in these hepatic steatosis models.Consequently,BTRC was identified as the E3 ligase for ATGL through predominant ubiquitination at the lysine 135 residue.Moreover,adenovirus-mediated knockdown of BTRC ameliorated steatosis in HFD-fed mouse livers and oleic acid-treated liver cells via upregulating the ATGL level.Taken together,BTRC plays a crucial role in hepatic steatosis as a new ATGL E3 ligase and may serve as a potential therapeutic target for treating NAFLD.
基金the National Nature Science Foundation of China(Grant No.31972677)the Construction Project of Liaoning Provincial Key Laboratory,China(2022JH13/10200026).
文摘The NS5A non-structural protein of classical swine fever virus(CSFV)is a multifunctional protein involved in viral genomic replication,protein translation,assembly of infectious virus particles,and regulation of cellular signaling pathways.Previous report showed that NS5A inhibited nuclear factor kappa B(NF-κB)signaling induced by poly(I:C);however,the mechanism involved has not been elucidated.Here,we reported that NS5A directly interacted with NF-κB essential modulator(NEMO),a regulatory subunit of the IκB kinase(IKK)complex,to inhibit the NF-κB signaling pathway.Further investigations showed that the zinc finger domain of NEMO and the aa 126–250 segment of NS5A are essential for the interaction between NEMO and NS5A.Mechanistic analysis revealed that NS5A mediated the proteasomal degradation of NEMO.Ubiquitination assay showed that NS5A induced the K27-linked but not the K48-linked polyubiquitination of NEMO for proteasomal degradation.In addition,NS5A blocked the K63-linked polyubiquitination of NEMO,thus inhibiting IKK phosphorylation,IκBαdegradation,and NF-κB activation.These findings revealed a novel mechanism by which CSFV inhibits host innate immunity,which might guide the drug design against CSFV in the future.
基金National Natural Science Foundation of China,Grant/Award Number:82130084Shaanxi Provincial Key R&D Program,Grant/Award Number:2021SF-110。
文摘Background The mechanism of hepatitis B virus(HBV)-induced carcinogenesis remains an area of interest.The accumulation of hepatitis B surface antigen in the endoplasmic reticulum(ER)of hepatocytes stimulates persistent ER stress.Activity of the unfolded protein response(UPR)pathway of ER stress may play an important role in inflammatory cancer transformation.How the protective UPR pathway is hijacked by cells as a tool for malignant transformation in HBV-related hepatocellular carcinoma(HCC)is still unclear.Here,we aimed to define the key molecule hyaluronan-mediated motility receptor(HMMR)in this process and explore its role under ER stress in HCC development.Methods An HBV-transgenic mouse model was used to characterize the pathological changes during the tumor progression.Proteomics and transcriptomics analyses were performed to identify the potential key molecule,screen the E3 ligase,and define the activation pathway.Quantitative real-time PCR and Western blotting were conducted to detect the expression of genes in tissues and cell lines.Luciferase reporter assay,chromatin immunoprecipitation,coimmunoprecipitation,immunoprecipitation,and immunofluorescence were employed to investigate the molecular mechanisms of HMMR under ER stress.Immunohistochemistry was used to clarify the expression patterns of HMMR and related molecules in human tissues.Results We found sustained activation of ER stress in the HBV-transgenic mouse model of hepatitis-fibrosis-HCC.HMMR was transcribed by c/EBP homologous protein(CHOP)and degraded by tripartite motif containing 29(TRIM29)after ubiquitination under ER stress,which caused the inconsistent expression of mRNA and protein.Dynamic expression of TRIM29 in the HCC progression regulated the dynamic expression of HMMR.HMMR could alleviate ER stress by increasing autophagic lysosome activity.The negative correlation between HMMR and ER stress,positive correlation between HMMR and autophagy,and negative correlation between ER stress and autophagy were verified in human tissues.Conclus
基金supported by grant from the National Natural Science Foundation of China(No.81670841).
文摘Background:Age-related macular degeneration(AMD)is the leading cause of vision loss worldwide.However,the mechanisms involved in the development and progression of AMD are poorly delineated.We aimed to explore the critical genes involved in the progression of AMD.Methods:The differentially expressed genes(DEGs)in AMD retinal pigment epithelial(RPE)/choroid tissues were identified using the microarray datasets GSE99248 and GSE125564,which were downloaded from the gene expression omnibus database.The overlapping DEGs from the two datasets were screened to identify DEG-related biological pathways using gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses.The hub genes were identified from these DEGs through protein-protein interaction network analyses.The expression levels of hub genes were evaluated by quantitative real-time polymerase chain reaction following the induction of senescence in ARPE-19 with FK866.Following the identification of AMD-related key genes,the potential small molecule compounds targeting the key genes were predicted by PharmacoDB.Finally,a microRNA-gene interaction network was constructed.Results:Microarray analyses identified 174 DEGs in the AMD RPE compared to the healthy RPE samples.These DEGs were primarily enriched in the pathways involved in the regulation of DNA replication,cell cycle,and proteasome-mediated protein polyubiquitination.Among the top ten hub genes,HSP90AA1,CHEK1,PSMA4,PSMD4,and PSMD8 were upregulated in the senescent ARPE-19 cells.Additionally,the drugs targeting HSP90AA1,CHEK1,and PSMA4 were identified.We hypothesize that Hsa-miR-16-5p might target four out of the five key DEGs in the AMD RPE.Conclusions:Based on our findings,HSP90AA1 is likely to be a central gene controlling the DNA replication and proteasome-mediated polyubiquitination during the RPE senescence observed in the progression of AMD.Targeting HSP90AA1,CHEK1,PSMA4,PSMD4,and/or PSMD8 genes through specific miRNAs or small molecules might potentially alleviate the progression of AMD
基金This work was supported by grants from the National Key Research and Development Program(2021YFC2300603),the National Natural Science Foundation of China(32000633,31730026,81930039)the Natural Science Foundation of Shandong Province(ZR2020QH136)+1 种基金the China Postdoctoral Science Foundation(2020M682187)the Postdoctoral Innovation Project of Shandong Province(202002012).
文摘Inflammasomes are essential components of the innate immune system and its defense against infections,whereas the dysregulation of inflammasome activation has a detrimental effect on human health.The activation of inflammasomes is subjected to tight regulation to maintain immune homeostasis,yet the underlying mechanism remains elusive.Here,we identify USP3 as a direct deubiquitinating enzyme(DUB)for ASC,the central adapter mediating the assembly and activation of most inflammasomes.USP3 removes the K48-linked ubiquitination on ASC and strengthens its stability by blocking proteasomal degradation.Additionally,USP3 promotes inflammasome activation,and this function was confirmed in mouse models of aluminum(Alum)-induced peritonitis,F.novicida infection and flagellin-induced pneumonia in vivo.Our work unveils that USP3 functions as a key regulator of ASC ubiquitination and maintains the physiological role of ASC in mediating inflammasome activation,and we propose a new mechanism by which the ubiquitination of ASC regulates inflammasome activation.
文摘Androgen receptor （AR） is able to promote stress-induced cell death independently of its transcription activity in androgen-independent prostate cancer cells. Yet, the underlying mechanism is incompletely understood. Here, we report that stress-induced proteasomal degradation of AR contributes to its pro-death activity. Upon exposure to ul- traviolet fight and staurosporine, AR underwent proteasomal degradation. Blockade of AR degradation significantly suppressed stress-induced apoptosis in androgen-independent prostate cancer cells. Ectopic expression of the AR N-terminal （AR-N） domain, which lacks DNA- and ligand-binding abilities, led to cell death without any additional death stimuli. Truncation analysis revealed that AR-N domain contains several sub-domains that regulate the pro- death activity of AR, specifically the first 105 amino acids, which function as a minimal pro-death domain acting upstream of caspases. The pro-apoptotic activity of AR N-terminal fragments was suppressed by ectopic expression of Bcl-2 or selected caspase inhibitors. Thus, our results reveal a novel mechanism by which AR promotes stressinduced cell death in androgen-independent prostate cancer cells.
文摘程序性死亡受体配体1(programmed death ligand 1,PD-L1)是肿瘤免疫检查点阻断治疗中的重要靶点,其在多种细胞中均有表达。肿瘤细胞可通过高表达PD-L1来增强程序性死亡受体1(programmed death 1,PD-1)抑制信号,从而促进肿瘤免疫逃逸。近年来,以抗PD-1/PD-L1抗体为代表的肿瘤免疫治疗给癌症治疗带来了革命性的变化。然而,肿瘤免疫治疗仅能对部分患者产生持久的疗效,多数患者对肿瘤免疫治疗的应答短暂或没有应答。研究发现,PD-L1的降解对肿瘤免疫治疗应答至关重要。本文综述了PD-L1的溶酶体降解途径、蛋白酶体降解途径及PD-L1降解与肿瘤免疫治疗的相互作用,旨在为进一步增强肿瘤免疫治疗的应答率和应答范围提供研究思路。
