AIM:To investigate the role of inositol-requiring enzyme 1α(IRE1α) in gut development of Xenopus lavies embryos.METHODS:Xenopus embryos were obtained with in vitro fertilization and cultured in 0.1 × MBSH.One a...AIM:To investigate the role of inositol-requiring enzyme 1α(IRE1α) in gut development of Xenopus lavies embryos.METHODS:Xenopus embryos were obtained with in vitro fertilization and cultured in 0.1 × MBSH.One and half nanogram of IRE1α,1 ng of IRE1α-GR mRNA,1 ng of IRE1αΔC-GR mRNA,and 50 ng of IRE1α morpholino oligonucleotide(MO) or XBP1(C)MO were injected into four blastomeres at 4-cell stage for scoring the phenotype and marker gene analysis.To rescue the effect of IRE1α MO,1 ng of IRE1α-GR mRNA was coinjected with 50 ng of MO.For the activation of the GR-fusion proteins,dexamethasone was prepared as 5 mmol/L stock solutions in 100% ethanol and applied to the mRNA injected embryos at desired stages in a concentration of 10 μmol/L in 0.1 × MBSH.Embryos were kept in dexamethasone up to stage 41.Whole-mount in situ hybridization was used to determine specific gene expression,such as IRE1α,IRE1β,Xbra and Xsox17α.IRE1α protein expression during Xenopus embryogenesis was detected by Western blotting.RESULTS:In the whole-mount in situ hybridization analysis,xenopus IRE1α and IRE1β showed quite different expression pattern during tadpole stage.The relatively higher expression of IRE1α was observed in the pancreas,and significant transcription of IRE1β was found in the liver.IRE1α protein could be detected at all developmental stages analyzed,from stage 1 to stage 42.Gain-of-function assay showed that IRE1α mRNA injected embryos at tailbud stage were nearly normal and the expression of the pan-mesodermal marker gene Xbra and the endodermal gene Xsox17α at stage 10.5 was not significantly changed in embryos injected with IRE1α mRNA as compared to uninjected control embryos.And at tadpole stage,the embryos injected with IRE1α-GR mRNA did not display overt phenotype,such as gut-coiling defect.Loss-of-function assay demonstrated that the IRE1α MO injected embryos were morphologically normal before the tailbud stages.We did not observe a significant change of mesodermal and endodermal marker gene expression,while after stage 40,about 80% of the MO injected embryos exhibited dramatic gut defects in which the guts did not coil,but other structures outside the gastrointestinal tract were relatively normal.To test if the phenotypes were specifically caused by the knockdown of IRE1α,a rescue experiment was performed by co-injection of IRE1α-GR mRMA with IRE1α MO.The data obtained demonstrated that the gut coiling defect was rescued.The deletion mutant of IRE1α was constructed,consisting of the N-terminal part without the C-terminal kinase and RNase domains named IRE1αΔC,to investigate the functional domain of IRE1α.Injection of IRE1αΔCGR mRNA caused similar morphological alterations with gut malformation by interfering with the function of endogenous xIRE1α.In order to investigate if IRE1α/XBP1 pathway was involved in gut development,50 ng of XBP1 MO was injected and the results showed that knockdown of XBP1 resulted in similar morphological alterations with gut-coiling defect at tadpole stage.CONCLUSION:IRE1α is not required for germ layer formation but for gut development in Xenopus lavies and it may function via XBP1-dependent pathway.展开更多
We previously reported that miR-124-3p is markedly upregulated in microglia-derived exosomes following repetitive mild traumatic brain injury.However,its impact on neuronal endoplasmic reticulum stress following repet...We previously reported that miR-124-3p is markedly upregulated in microglia-derived exosomes following repetitive mild traumatic brain injury.However,its impact on neuronal endoplasmic reticulum stress following repetitive mild traumatic brain injury remains unclear.In this study,we first used an HT22 scratch injury model to mimic traumatic brain injury,then co-cultured the HT22 cells with BV2 microglia expressing high levels of miR-124-3p.We found that exosomes containing high levels of miR-124-3p attenuated apoptosis and endoplasmic reticulum stress.Furthermore,luciferase reporter assay analysis confirmed that miR-124-3p bound specifically to the endoplasmic reticulum stress-related protein IRE1α,while an IRE1αfunctional salvage experiment confirmed that miR-124-3p targeted IRE1αand reduced its expression,thereby inhibiting endoplasmic reticulum stress in injured neurons.Finally,we delivered microglia-derived exosomes containing miR-124-3p intranasally to a mouse model of repetitive mild traumatic brain injury and found that endoplasmic reticulum stress and apoptosis levels in hippocampal neurons were significantly reduced.These findings suggest that,after repetitive mild traumatic brain injury,miR-124-3 can be transferred from microglia-derived exosomes to injured neurons,where it exerts a neuroprotective effect by inhibiting endoplasmic reticulum stress.Therefore,microglia-derived exosomes containing miR-124-3p may represent a novel therapeutic strategy for repetitive mild traumatic brain injury.展开更多
Objective:To investigate the effects of astragalosideⅣ(AS-Ⅳ)on podocyte injury of diabetic nephropathy(DN)and reveal its potential mechanism.Methods:In in vitro experiment,podocytes were divided into 4 groups,normal...Objective:To investigate the effects of astragalosideⅣ(AS-Ⅳ)on podocyte injury of diabetic nephropathy(DN)and reveal its potential mechanism.Methods:In in vitro experiment,podocytes were divided into 4 groups,normal,high glucose(HG),inositol-requiring enzyme 1(IRE-1)αactivator(HG+thapsigargin1μmol/L),and IRE-1αinhibitor(HG+STF-083010,20μmol/L)groups.Additionally,podocytes were divided into 4 groups,including normal,HG,AS-Ⅳ(HG+AS-Ⅳ20μmol/L),and IRE-1αinhibitor(HG+STF-083010,20μmol/L)groups,respectively.After 24 h treatment,the morphology of podocytes and endoplasmic reticulum(ER)was observed by electron microscopy.The expressions of glucose-regulated protein 78(GRP78)and IRE-1αwere detected by cellular immunofluorescence.In in vivo experiment,DN rat model was established via a consecutive 3-day intraperitoneal streptozotocin(STZ)injections.A total of 40 rats were assigned into the normal,DN,AS-Ⅳ[AS-Ⅳ40 mg/(kg·d)],and IRE-1αinhibitor[STF-083010,10 mg/(kg·d)]groups(n=10),respectively.The general condition,24-h urine volume,random blood glucose,urinary protein excretion rate(UAER),blood urea nitrogen(BUN),and serum creatinine(SCr)levels of rats were measured after 8 weeks of intervention.Pathological changes in the renal tissue were observed by hematoxylin and eosin(HE)staining.Quantitative reverse transcription-polymerase chain reaction(RT-PCR)and Western blot were used to detect the expressions of GRP78,IRE-1α,nuclear factor kappa Bp65(NF-κBp65),interleukin(IL)-1β,NLR family pyrin domain containing 3(NLRP3),caspase-1,gasdermin D-N(GSDMD-N),and nephrin at the mRNA and protein levels in vivo and in vitro,respectively.Results:Cytoplasmic vacuolation and ER swelling were observed in the HG and IRE-1αactivator groups.Podocyte morphology and ER expansion were improved in AS-Ⅳand IRE-1αinhibitor groups compared with HG group.Cellular immunofluorescence showed that compared with the normal group,the fluorescence intensity of GRP78 and IRE-1αin the HG and IRE-1αactivator groups were significantly increased whereas decreased in AS-Ⅳand IRE-1αinhibitor groups(P<0.05).Compared with the normal group,the mRNA and protein expressions of GRP78,IRE-1α,NF-κBp65,IL-1β,NLRP3,caspase-1 and GSDMD-N in the HG group was increased(P<0.05).Compared with HG group,the expression of above indices was decreased in the AS-Ⅳand IRE-1αinhibitor groups,and the expression in the IRE-1αactivator group was increased(P<0.05).The expression of nephrin was decreased in the HG group,and increased in AS-Ⅳand IRE-1αinhibitor groups(P<0.05).The in vivo experiment results revealed that compared to the normal group,the levelse of blood glucose,triglyceride,total cholesterol,BUN,SCr and urinary protein in the DN group were higher(P<0.05).Compared with DN group,the above indices in AS-Ⅳand IRE-1αinhibitor groups were decreased(P<0.05).HE staining revealed glomerular hypertrophy,mesangial widening and mesangial cell proliferation in the renal tissue of the DN group.Compared with the DN group,the above pathological changes in renal tissue of AS-Ⅳand IRE-1αinhibitor groups were alleviated.Quantitative RT-PCR and Western blot results of GRP78,IRE-1α,NF-κBp65,IL-1β,NLRP3,caspase-1 and GSDMD-N were consistent with immunofluorescence analysis.Conclusion:AS-Ⅳcould reduce ERS and inflammation,improve podocyte pyroptosis,thus exerting a podocyteprotective effect in DN,through regulating IRE-1α/NF-κB/NLRP3 signaling pathway.展开更多
Although the functional parameters of micro RNAs(mi RNAs)have been explored to some extent,the roles of these molecules in coronavirus infection and the regulatory mechanism of mi RNAs in virus infection are still unc...Although the functional parameters of micro RNAs(mi RNAs)have been explored to some extent,the roles of these molecules in coronavirus infection and the regulatory mechanism of mi RNAs in virus infection are still unclear.Transmissible gastroenteritis virus(TGEV)is an enteropathgenic coronavirus and causes high morbidity and mortality in suckling piglets.Here,we demonstrated that microRNA-27b-3p(miR-27b-3p)suppressed TGEV replication by directly targeting porcine suppressor of cytokine signaling 6(SOCS6),while TGEV infection downregulated miR-27b-3p expression in swine testicular(ST)cells and in piglets.Mechanistically,the decrease of miR-27b-3p expression during TGEV infection was mediated by the activated inositolrequiring enzyme 1(IRE1)pathway of the endoplasmic reticulum(ER)stress.Further studies showed that when ER stress was induced by TGEV,IRE1 acted as an RNase activated by autophosphorylation and unconventionally spliced m RNA encoding a potent transcription factor,X-box-binding protein 1(Xbp1s).Xbp1s inhibited the transcription of miR-27 and ultimately reduced the production of miR-27b-3p.Therefore,our findings indicate that TGEV inhibits the expression of an anti-coronavirus micro RNA through the IRE1 pathway and suggest a novel way in which coronavirus regulates the host cell response to infection.展开更多
Endoplasmic reticulum(ER)stress occurs when ER homeostasis is perturbed with accumulation of unfolded/misfolded protein or calcium depletion.The unfolded protein response(UPR),comprising of inositol-requiring enzyme 1...Endoplasmic reticulum(ER)stress occurs when ER homeostasis is perturbed with accumulation of unfolded/misfolded protein or calcium depletion.The unfolded protein response(UPR),comprising of inositol-requiring enzyme 1 a(IRE1 a),double-stranded RNA-dependent protein kinase(PKR)-like ER kinase(PERK)and activating transcription factor 6(ATF6)signaling pathways,is a protective cellular response activated by ER stress.However,UPR activation can also induce cell death upon persistent ER stress.The liver is susceptible to ER stress given its synthetic and other biological functions.Numerous studies from human liver samples and animal disease models have indicated a crucial role of ER stress and the UPR signaling pathways in the pathogenesis of liver diseases,including non-alcoholic fatty liver disease(NAFLD),alcoholic liver disease(ALD),alpha-1 antitrypsin(AAT)deficiency(AATD),cholestatic liver disease,drug-induced liver injury,ischemia/reperfusion(I/R)injury,viral hepatitis and hepatocel-lular carcinoma(HCC).Extensive investigations have demonstrated the potential underlying mechanisms of the induction of ER stress and the contribution of the UPR pathways during the development of the diseases.Moreover,ER stress and the UPR proteins and genes have become emerging therapeutic targets to treat liver diseases.展开更多
Objective:To examine whether exposure of mouse neuronal cells to radiofrequency fields used in mobile communication devices can induce stress in endoplasmic reticulum(ER)and activate unfolded protein response(UPR).Met...Objective:To examine whether exposure of mouse neuronal cells to radiofrequency fields used in mobile communication devices can induce stress in endoplasmic reticulum(ER)and activate unfolded protein response(UPR).Methods:HT22 mouse hippocampus neuronal cells were exposed to continuous wave 900 MHz radiofrequency fields(RF)at 120μW/cm2 power intensity for 4 h/d for 5 consecutive days.The positive control cells were irradiated with 4 Gy of 60Coγ-rays at a dose rate of 0.5 Gy/min(GR).Twenty-four hours after the last exposure,cells were collected,and the expressions of sensor transmembrane proteins were detected using Western blot analysis.Results:The expression levels of Ire1,PERK,p-IRE1 and p-PERK,GRP78 and CHOP proteins were detected.There were no statistically significant differences in the expression levels of IRE1 and PERK proteins in control(CT),sham(SH)-,RF-and GR-exposed cells(P<0.05).The phosphorylated protein levels of p-IRE1 and p-PERK were significantly increased in cells exposed to RF and GR(P<0.05).The expression levels of GRP78 and CHOP were significantly increased in RF-and GR-exposed cells compared to CT and SH-exposed cells(P<0.05).Cells treated with 1μg/ml TM for 24 h showed significantly increased expression levels of GRP78 and CHOP proteins compared to controls(P<0.05).In the presence of 2 mmol/L PBA,TM-induced increased levels of GRP78 and CHOP proteins were reduced(P<0.05).Conclusions:The exposure of non-ionizing 900 MHz RF was able to cause stress in HT22 mouse neuronal cells and activated UPR in ER.Since UPR plays an important role in both cell survival(when UPR is mitigated)and apoptosis/death(under unresolvable stress conditions),further studies are required to determine the fate of the cells exposed to RF.展开更多
基金Supported by The National Natural Science Foundation of China,No.30971680A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions, No.JX10131801101
文摘AIM:To investigate the role of inositol-requiring enzyme 1α(IRE1α) in gut development of Xenopus lavies embryos.METHODS:Xenopus embryos were obtained with in vitro fertilization and cultured in 0.1 × MBSH.One and half nanogram of IRE1α,1 ng of IRE1α-GR mRNA,1 ng of IRE1αΔC-GR mRNA,and 50 ng of IRE1α morpholino oligonucleotide(MO) or XBP1(C)MO were injected into four blastomeres at 4-cell stage for scoring the phenotype and marker gene analysis.To rescue the effect of IRE1α MO,1 ng of IRE1α-GR mRNA was coinjected with 50 ng of MO.For the activation of the GR-fusion proteins,dexamethasone was prepared as 5 mmol/L stock solutions in 100% ethanol and applied to the mRNA injected embryos at desired stages in a concentration of 10 μmol/L in 0.1 × MBSH.Embryos were kept in dexamethasone up to stage 41.Whole-mount in situ hybridization was used to determine specific gene expression,such as IRE1α,IRE1β,Xbra and Xsox17α.IRE1α protein expression during Xenopus embryogenesis was detected by Western blotting.RESULTS:In the whole-mount in situ hybridization analysis,xenopus IRE1α and IRE1β showed quite different expression pattern during tadpole stage.The relatively higher expression of IRE1α was observed in the pancreas,and significant transcription of IRE1β was found in the liver.IRE1α protein could be detected at all developmental stages analyzed,from stage 1 to stage 42.Gain-of-function assay showed that IRE1α mRNA injected embryos at tailbud stage were nearly normal and the expression of the pan-mesodermal marker gene Xbra and the endodermal gene Xsox17α at stage 10.5 was not significantly changed in embryos injected with IRE1α mRNA as compared to uninjected control embryos.And at tadpole stage,the embryos injected with IRE1α-GR mRNA did not display overt phenotype,such as gut-coiling defect.Loss-of-function assay demonstrated that the IRE1α MO injected embryos were morphologically normal before the tailbud stages.We did not observe a significant change of mesodermal and endodermal marker gene expression,while after stage 40,about 80% of the MO injected embryos exhibited dramatic gut defects in which the guts did not coil,but other structures outside the gastrointestinal tract were relatively normal.To test if the phenotypes were specifically caused by the knockdown of IRE1α,a rescue experiment was performed by co-injection of IRE1α-GR mRMA with IRE1α MO.The data obtained demonstrated that the gut coiling defect was rescued.The deletion mutant of IRE1α was constructed,consisting of the N-terminal part without the C-terminal kinase and RNase domains named IRE1αΔC,to investigate the functional domain of IRE1α.Injection of IRE1αΔCGR mRNA caused similar morphological alterations with gut malformation by interfering with the function of endogenous xIRE1α.In order to investigate if IRE1α/XBP1 pathway was involved in gut development,50 ng of XBP1 MO was injected and the results showed that knockdown of XBP1 resulted in similar morphological alterations with gut-coiling defect at tadpole stage.CONCLUSION:IRE1α is not required for germ layer formation but for gut development in Xenopus lavies and it may function via XBP1-dependent pathway.
基金supported by the Haihe Laboratory of Cell Ecosystem Innovation Fund,No.22HHXBSS00047(to PL)the National Natural Science Foundation of China,Nos.82072166(to PL),82071394(to XG)+4 种基金Science and Technology Planning Project of Tianjin,No.20YFZCSY00030(to PL)Science and Technology Project of Tianjin Municipal Health Commission,No.TJWJ2021QN005(to XG)Tianjin Key Medical Discipline(Specialty)Construction Project,No.TJYXZDXK-006ATianjin Municipal Education Commission Scientific Research Program Project,No.2020KJ164(to JZ)China Postdoctoral Science Foundation,No.2022M712392(to ZY).
文摘We previously reported that miR-124-3p is markedly upregulated in microglia-derived exosomes following repetitive mild traumatic brain injury.However,its impact on neuronal endoplasmic reticulum stress following repetitive mild traumatic brain injury remains unclear.In this study,we first used an HT22 scratch injury model to mimic traumatic brain injury,then co-cultured the HT22 cells with BV2 microglia expressing high levels of miR-124-3p.We found that exosomes containing high levels of miR-124-3p attenuated apoptosis and endoplasmic reticulum stress.Furthermore,luciferase reporter assay analysis confirmed that miR-124-3p bound specifically to the endoplasmic reticulum stress-related protein IRE1α,while an IRE1αfunctional salvage experiment confirmed that miR-124-3p targeted IRE1αand reduced its expression,thereby inhibiting endoplasmic reticulum stress in injured neurons.Finally,we delivered microglia-derived exosomes containing miR-124-3p intranasally to a mouse model of repetitive mild traumatic brain injury and found that endoplasmic reticulum stress and apoptosis levels in hippocampal neurons were significantly reduced.These findings suggest that,after repetitive mild traumatic brain injury,miR-124-3 can be transferred from microglia-derived exosomes to injured neurons,where it exerts a neuroprotective effect by inhibiting endoplasmic reticulum stress.Therefore,microglia-derived exosomes containing miR-124-3p may represent a novel therapeutic strategy for repetitive mild traumatic brain injury.
基金Supported by the International Cooperation Project of Department of Science and Technology of Shanxi Province(No.201903D421057)the Youth Fund Project of Department of Science and Technology of Shanxi Province(No.201901D211485)。
文摘Objective:To investigate the effects of astragalosideⅣ(AS-Ⅳ)on podocyte injury of diabetic nephropathy(DN)and reveal its potential mechanism.Methods:In in vitro experiment,podocytes were divided into 4 groups,normal,high glucose(HG),inositol-requiring enzyme 1(IRE-1)αactivator(HG+thapsigargin1μmol/L),and IRE-1αinhibitor(HG+STF-083010,20μmol/L)groups.Additionally,podocytes were divided into 4 groups,including normal,HG,AS-Ⅳ(HG+AS-Ⅳ20μmol/L),and IRE-1αinhibitor(HG+STF-083010,20μmol/L)groups,respectively.After 24 h treatment,the morphology of podocytes and endoplasmic reticulum(ER)was observed by electron microscopy.The expressions of glucose-regulated protein 78(GRP78)and IRE-1αwere detected by cellular immunofluorescence.In in vivo experiment,DN rat model was established via a consecutive 3-day intraperitoneal streptozotocin(STZ)injections.A total of 40 rats were assigned into the normal,DN,AS-Ⅳ[AS-Ⅳ40 mg/(kg·d)],and IRE-1αinhibitor[STF-083010,10 mg/(kg·d)]groups(n=10),respectively.The general condition,24-h urine volume,random blood glucose,urinary protein excretion rate(UAER),blood urea nitrogen(BUN),and serum creatinine(SCr)levels of rats were measured after 8 weeks of intervention.Pathological changes in the renal tissue were observed by hematoxylin and eosin(HE)staining.Quantitative reverse transcription-polymerase chain reaction(RT-PCR)and Western blot were used to detect the expressions of GRP78,IRE-1α,nuclear factor kappa Bp65(NF-κBp65),interleukin(IL)-1β,NLR family pyrin domain containing 3(NLRP3),caspase-1,gasdermin D-N(GSDMD-N),and nephrin at the mRNA and protein levels in vivo and in vitro,respectively.Results:Cytoplasmic vacuolation and ER swelling were observed in the HG and IRE-1αactivator groups.Podocyte morphology and ER expansion were improved in AS-Ⅳand IRE-1αinhibitor groups compared with HG group.Cellular immunofluorescence showed that compared with the normal group,the fluorescence intensity of GRP78 and IRE-1αin the HG and IRE-1αactivator groups were significantly increased whereas decreased in AS-Ⅳand IRE-1αinhibitor groups(P<0.05).Compared with the normal group,the mRNA and protein expressions of GRP78,IRE-1α,NF-κBp65,IL-1β,NLRP3,caspase-1 and GSDMD-N in the HG group was increased(P<0.05).Compared with HG group,the expression of above indices was decreased in the AS-Ⅳand IRE-1αinhibitor groups,and the expression in the IRE-1αactivator group was increased(P<0.05).The expression of nephrin was decreased in the HG group,and increased in AS-Ⅳand IRE-1αinhibitor groups(P<0.05).The in vivo experiment results revealed that compared to the normal group,the levelse of blood glucose,triglyceride,total cholesterol,BUN,SCr and urinary protein in the DN group were higher(P<0.05).Compared with DN group,the above indices in AS-Ⅳand IRE-1αinhibitor groups were decreased(P<0.05).HE staining revealed glomerular hypertrophy,mesangial widening and mesangial cell proliferation in the renal tissue of the DN group.Compared with the DN group,the above pathological changes in renal tissue of AS-Ⅳand IRE-1αinhibitor groups were alleviated.Quantitative RT-PCR and Western blot results of GRP78,IRE-1α,NF-κBp65,IL-1β,NLRP3,caspase-1 and GSDMD-N were consistent with immunofluorescence analysis.Conclusion:AS-Ⅳcould reduce ERS and inflammation,improve podocyte pyroptosis,thus exerting a podocyteprotective effect in DN,through regulating IRE-1α/NF-κB/NLRP3 signaling pathway.
基金supported by the Heilongjiang Postdoctoral fund(LBH-Z18207)the National Natural Science Foundation of China(31802198)+2 种基金the Fundamental Research Funds for the Provincial Universities(2018-KYYWF-0553)the National Key Research and Development Program of China(2017YFC0908001)the Spark Research Fund from the Fourth Affiliated Hospital of Harbin Medical University(HYDSYXH201914)。
文摘Although the functional parameters of micro RNAs(mi RNAs)have been explored to some extent,the roles of these molecules in coronavirus infection and the regulatory mechanism of mi RNAs in virus infection are still unclear.Transmissible gastroenteritis virus(TGEV)is an enteropathgenic coronavirus and causes high morbidity and mortality in suckling piglets.Here,we demonstrated that microRNA-27b-3p(miR-27b-3p)suppressed TGEV replication by directly targeting porcine suppressor of cytokine signaling 6(SOCS6),while TGEV infection downregulated miR-27b-3p expression in swine testicular(ST)cells and in piglets.Mechanistically,the decrease of miR-27b-3p expression during TGEV infection was mediated by the activated inositolrequiring enzyme 1(IRE1)pathway of the endoplasmic reticulum(ER)stress.Further studies showed that when ER stress was induced by TGEV,IRE1 acted as an RNase activated by autophosphorylation and unconventionally spliced m RNA encoding a potent transcription factor,X-box-binding protein 1(Xbp1s).Xbp1s inhibited the transcription of miR-27 and ultimately reduced the production of miR-27b-3p.Therefore,our findings indicate that TGEV inhibits the expression of an anti-coronavirus micro RNA through the IRE1 pathway and suggest a novel way in which coronavirus regulates the host cell response to infection.
基金This work was supported by USA National Institute of Diabetes and Digestive and Kidney Diseases(NIDDK)R01 DK093807.
文摘Endoplasmic reticulum(ER)stress occurs when ER homeostasis is perturbed with accumulation of unfolded/misfolded protein or calcium depletion.The unfolded protein response(UPR),comprising of inositol-requiring enzyme 1 a(IRE1 a),double-stranded RNA-dependent protein kinase(PKR)-like ER kinase(PERK)and activating transcription factor 6(ATF6)signaling pathways,is a protective cellular response activated by ER stress.However,UPR activation can also induce cell death upon persistent ER stress.The liver is susceptible to ER stress given its synthetic and other biological functions.Numerous studies from human liver samples and animal disease models have indicated a crucial role of ER stress and the UPR signaling pathways in the pathogenesis of liver diseases,including non-alcoholic fatty liver disease(NAFLD),alcoholic liver disease(ALD),alpha-1 antitrypsin(AAT)deficiency(AATD),cholestatic liver disease,drug-induced liver injury,ischemia/reperfusion(I/R)injury,viral hepatitis and hepatocel-lular carcinoma(HCC).Extensive investigations have demonstrated the potential underlying mechanisms of the induction of ER stress and the contribution of the UPR pathways during the development of the diseases.Moreover,ER stress and the UPR proteins and genes have become emerging therapeutic targets to treat liver diseases.
基金This research is supported by funding from the National Natural Science Foundation of China(Grant No.81373025).
文摘Objective:To examine whether exposure of mouse neuronal cells to radiofrequency fields used in mobile communication devices can induce stress in endoplasmic reticulum(ER)and activate unfolded protein response(UPR).Methods:HT22 mouse hippocampus neuronal cells were exposed to continuous wave 900 MHz radiofrequency fields(RF)at 120μW/cm2 power intensity for 4 h/d for 5 consecutive days.The positive control cells were irradiated with 4 Gy of 60Coγ-rays at a dose rate of 0.5 Gy/min(GR).Twenty-four hours after the last exposure,cells were collected,and the expressions of sensor transmembrane proteins were detected using Western blot analysis.Results:The expression levels of Ire1,PERK,p-IRE1 and p-PERK,GRP78 and CHOP proteins were detected.There were no statistically significant differences in the expression levels of IRE1 and PERK proteins in control(CT),sham(SH)-,RF-and GR-exposed cells(P<0.05).The phosphorylated protein levels of p-IRE1 and p-PERK were significantly increased in cells exposed to RF and GR(P<0.05).The expression levels of GRP78 and CHOP were significantly increased in RF-and GR-exposed cells compared to CT and SH-exposed cells(P<0.05).Cells treated with 1μg/ml TM for 24 h showed significantly increased expression levels of GRP78 and CHOP proteins compared to controls(P<0.05).In the presence of 2 mmol/L PBA,TM-induced increased levels of GRP78 and CHOP proteins were reduced(P<0.05).Conclusions:The exposure of non-ionizing 900 MHz RF was able to cause stress in HT22 mouse neuronal cells and activated UPR in ER.Since UPR plays an important role in both cell survival(when UPR is mitigated)and apoptosis/death(under unresolvable stress conditions),further studies are required to determine the fate of the cells exposed to RF.
