Background and Aims:Ras-related nuclear(RAN)protein is a small GTP-binding protein that is indispensable for the translocation of RNA and proteins through the nuclear pore complex.Recent studies have indicated that RA...Background and Aims:Ras-related nuclear(RAN)protein is a small GTP-binding protein that is indispensable for the translocation of RNA and proteins through the nuclear pore complex.Recent studies have indicated that RAN plays an important role in virus infection.However,the role of RAN in hepatitis C virus(HCV)infection is unclear.The objective of this study was to investigate the role and underlying mechanisms of RAN in HCV infection.Methods:Huh7.5.1 cells were infected with the JC1-Luc virus for 24 h and then were incubated with complete medium for an additional 48 h.HCV infection and RAN expression were determined using luciferase assay,quantitative reverse transcription-PCR and western blotting.Small interfering RNA was used to silence RAN.Western blotting and immunofluorescence were used to evaluate the cytoplasmic translocation of polypyrimidine tract-binding(PTB),and coimmunoprecipitation was used to examine the interaction between RAN and PTB.Results:HCV infection significantly induced RAN expression and cytoplasmic redistribution of PTB.Knockdown of RAN dramatically inhibited HCV infection and the cytoplasmic accumulation of PTB.Colocalization of RAN and PTB was determined by immunofluorescence,and a direct interaction of RAN with PTB was demonstrated by coimmunoprecipitation.Conclusions:PTB in the host cytoplasm is directly associated with HCV replication.These findings demonstrate that the involvement of RAN in HCV infection is mediated by influencing the cytoplasmic translocation of PTB.展开更多
Epidermal growth factor （EGF） may increase cell motility, an event implicated in cancer cell invasion and metastasis. However, the underlying mechanisms for EGF-induced cell motility remain elusive. In this study, w...Epidermal growth factor （EGF） may increase cell motility, an event implicated in cancer cell invasion and metastasis. However, the underlying mechanisms for EGF-induced cell motility remain elusive. In this study, we found that EGF treatment could activate Ras-related C3 botulinum toxin substrate 1 （Racl）, PI3K/Akt and p21- actived kinase （PAK1） along with cell migration. Ectopic expression of PAK1 K299R, a dominant negative PAK1 mutant, could largely abolish EGF-induced cell migration. Blocking PI3K/Akt signalling with LY294002 or Akt siRNA remarkably inhibited both EGF-induced PAK1 activation and cell migration. Furthermore, expression of dominant-negative Racl （T17N） could largely block EGF-induced PI3K/Akt-PAK1 activation and cell migration. Interestingly, EGF could induce a significant production of ROS, and N-acetyl-L-cysteine, a scavenger of ROS which abolished the EGF-induced ROS generation, cell migration, as well as activation of PI3K/Akt and PAK, but not Racl. Our study demonstrated that EGF-induced cell migration involves a cascade of signalling events, including activation of Racl, generation of ROS and subsequent activation of PI3K/Akt and PAK1.展开更多
Aging skeletons display decreased bone mass,increased marrow adiposity,and impaired bone marrow mesenchymal stem cells(MSCs).Apoptosis is a programmed cell death process that generates a large number of apoptotic vesi...Aging skeletons display decreased bone mass,increased marrow adiposity,and impaired bone marrow mesenchymal stem cells(MSCs).Apoptosis is a programmed cell death process that generates a large number of apoptotic vesicles(apoVs).Dysregulated apoptosis has been closely linked to senescence-associated diseases.However,whether apoVs mediate agingrelated bone loss is not clear.In this study,we showed that young MSC-derived apoVs effectively rejuvenated the nuclear abnormalities of aged bone marrow MSCs and restored their impaired self-renewal,osteo-/adipo-genic lineage differentiation capacities via activating autophagy.Mechanistically,apoptotic young MSCs generated and enriched a high level of Ras-related protein 7(Rab7)into apoVs.Subsequently,recipient aged MSCs reused apoV-derived Rab7 to restore autolysosomes formation,thereby contributing to autophagy flux activation and MSC rejuvenation.Moreover,systemic infusion of young MSC-derived apoVs enhanced bone mass,reduced marrow adiposity,and recused the impairment of recipient MSCs in aged mice.Our findings reveal the role of apoVs in rejuvenating aging-MSCs via restoring autolysosome formation and provide a potential approach for treating age-related bone loss.展开更多
Background:Our previous studies demonstrated that eyes absent homolog 4(EYA4),a member of the eye devel-opment-related EYA family in Drosophila,is frequently methylated and silenced in hepatocellular carcinoma(HCC)spe...Background:Our previous studies demonstrated that eyes absent homolog 4(EYA4),a member of the eye devel-opment-related EYA family in Drosophila,is frequently methylated and silenced in hepatocellular carcinoma(HCC)specimens and associated with shorter survival.The current work aimed to explore the mechanisms through which EYA4 functions as a tumor suppressor in HCC.Methods:Stable EYA4-expressing plasmid(pEYA4)transfectants of the human HCC cell lines Huh-7 and PLC/PRF/5(PLC)were established.Xenografts tumors were established via subcutaneous injection of the stable transfectants into BALB/c nude mice.Tissue samples were obtained from 75 pathologically diagnosed HCC patients.Quantitative real-time polymerase chain reaction,Western blotting and immunohistochemistry were performed to determine the expression of EYA4 in cell lines,xenografts and clinical specimens.The cell proliferation,colony formation,invasiveness and tumor formation of stable transfectants were studied.A gene expression microarray was utilized to screen genes regulated by EYA4 expression.The effect of EYA4 on nuclear factor-κB(NF-κB)/RAS-related protein 1(RAP1)signaling was demonstrated through the co-transfection of pEYA4 and Flag-tagged RAS-related protein 1A gene-expressing plasmid(Flag-RAP1A),functional studies,chromatin immunoprecipitation,immunofluorescence staining and cellular ubiquitination assay.Results:The restoration of EYA4 expression in HCC cell lines suppressed cell proliferation,inhibited clonogenic outgrowth,reduced cell invasion and restrained xenograft tumor growth,and Flag-RAP1A reversed the suppressive effects of pEYA4 in vitro.Activation of NF-κB with tumor necrosis factor-α(TNF-α)increased the binding of p65 to the RAP1A gene promoter and up-regulated RAP1 protein expression.The inhibition of NF-κB with BAY 11-7085 and p65 siRNA successfully blocked TNF-α-induced RAP1 up-regulation.EYA4 antagonized the TNF-α-induced phosphoryla-tion and ubiquitination of inhibitor of NF-κBα(IκBα)as well as the nuclear translocation and transactivation of p65,resulting in repressed NF-κB activity and RAP1 expression.Blocking the serine/threonine phosphatase activity of EYA4 with calyculin A notably abrogated its suppressive effect on NF-κB activity.In addition,EYA4 expression was inversely correlated with IκBα/RAP1 activity in clinical HCC specimens.Conclusion:Our findings provide a functional and mechanistic basis for identifying EYA4 as a bona fide tumor sup-pressor that disrupts aberrant activation of the NF-κB/RAP1 signaling pathway and thus orchestrates a physiological impediment to HCC growth and invasion.展开更多
Metastasis is one of the main reasons causing death in cancer patients.It was reported that chemotherapy might induce metastasis.In order to uncover the mechanism of chemotherapy-induced metastasis and find solutions ...Metastasis is one of the main reasons causing death in cancer patients.It was reported that chemotherapy might induce metastasis.In order to uncover the mechanism of chemotherapy-induced metastasis and find solutions to inhibit treatment-induced metastasis,the relationship between epithelial-mesenchymal transition(EMT)and doxorubicin(DOX)treatment was investigated and a redox-sensitive small interfering RNA(siRNA)delivery system was designed.DOX-related reactive oxygen species(ROS)were found to be responsible for the invasiveness of tumor cells in vitro,causing enhanced EMT and cytoskeleton reconstruction regulated by Ras-related C3 botulinum toxin substrate 1(RAC1).In order to decrease RAC1,a redox-sensitive glycolipid drug delivery system(chitosan-ss-stearylamine conjugate(CSO-ss-SA))was designed to carry siRNA,forming a gene delivery system(CSO-ss-SA/siRNA)downregulating RAC1.CSO-ss-SA/siRNA exhibited an enhanced redox sensitivity compared to nonresponsive complexes in 10 mmol/L glutathione(GSH)and showed a significant safety.CSO-ss-SA/siRNA could effectively transmit siRNA into tumor cells,reducing the expression of RAC1 protein by 38.2%and decreasing the number of tumor-induced invasion cells by 42.5%.When combined with DOX,CSO-ss-SA/siRNA remarkably inhibited the chemotherapy-induced EMT in vivo and enhanced therapeutic efficiency.The present study indicates that RAC1 protein is a key regulator of chemotherapy-induced EMT and CSO-ss-SA/siRNA silencing RAC1 could efficiently decrease the tumor metastasis risk after chemotherapy.展开更多
基金The work was supported by the Anhui Provincial Natural Science Foundation(1608085QH172)States S&T Projects of 13th Five Year(2018ZX10302206),Chinese Founda-tion for Hepatitis Prevention and Control(TQGB20200151,TQGB20180367)Anhui Key Program of Medical Scien-tific Research of China(#2010A010).
文摘Background and Aims:Ras-related nuclear(RAN)protein is a small GTP-binding protein that is indispensable for the translocation of RNA and proteins through the nuclear pore complex.Recent studies have indicated that RAN plays an important role in virus infection.However,the role of RAN in hepatitis C virus(HCV)infection is unclear.The objective of this study was to investigate the role and underlying mechanisms of RAN in HCV infection.Methods:Huh7.5.1 cells were infected with the JC1-Luc virus for 24 h and then were incubated with complete medium for an additional 48 h.HCV infection and RAN expression were determined using luciferase assay,quantitative reverse transcription-PCR and western blotting.Small interfering RNA was used to silence RAN.Western blotting and immunofluorescence were used to evaluate the cytoplasmic translocation of polypyrimidine tract-binding(PTB),and coimmunoprecipitation was used to examine the interaction between RAN and PTB.Results:HCV infection significantly induced RAN expression and cytoplasmic redistribution of PTB.Knockdown of RAN dramatically inhibited HCV infection and the cytoplasmic accumulation of PTB.Colocalization of RAN and PTB was determined by immunofluorescence,and a direct interaction of RAN with PTB was demonstrated by coimmunoprecipitation.Conclusions:PTB in the host cytoplasm is directly associated with HCV replication.These findings demonstrate that the involvement of RAN in HCV infection is mediated by influencing the cytoplasmic translocation of PTB.
基金supported by grants from the National Natural Science Foundation of China (No. 30872926)the Program for AdvancedTalents within Six Industries of Jiangsu Province (08-D) to Dr. Luo Gu+1 种基金the Science Development Foundation of Nanjing Medical University (No. 2010NJMUZ35)the Research Program funded by Schoolof Basic Medical Science, Nanjing Medical University to Dr. Jun Du
文摘Epidermal growth factor （EGF） may increase cell motility, an event implicated in cancer cell invasion and metastasis. However, the underlying mechanisms for EGF-induced cell motility remain elusive. In this study, we found that EGF treatment could activate Ras-related C3 botulinum toxin substrate 1 （Racl）, PI3K/Akt and p21- actived kinase （PAK1） along with cell migration. Ectopic expression of PAK1 K299R, a dominant negative PAK1 mutant, could largely abolish EGF-induced cell migration. Blocking PI3K/Akt signalling with LY294002 or Akt siRNA remarkably inhibited both EGF-induced PAK1 activation and cell migration. Furthermore, expression of dominant-negative Racl （T17N） could largely block EGF-induced PI3K/Akt-PAK1 activation and cell migration. Interestingly, EGF could induce a significant production of ROS, and N-acetyl-L-cysteine, a scavenger of ROS which abolished the EGF-induced ROS generation, cell migration, as well as activation of PI3K/Akt and PAK, but not Racl. Our study demonstrated that EGF-induced cell migration involves a cascade of signalling events, including activation of Racl, generation of ROS and subsequent activation of PI3K/Akt and PAK1.
基金This work was supported by grants from the National Natural Science Foundation of China(No.82170924)the National Key R&D Program of China(No.2021YFA1100600)+2 种基金the Pearl River Talent Recruitment Program(Nos.2019ZT08Y485 and 2019JC01Y138)the Guangdong Financial Fund for High-Caliber Hospital Construction(174-2018-XMZC-0001-03-0125,C-03 and D-11)the Sun Yat-sen University Young Teacher Key Cultivation Project(No.18ykzd05).
文摘Aging skeletons display decreased bone mass,increased marrow adiposity,and impaired bone marrow mesenchymal stem cells(MSCs).Apoptosis is a programmed cell death process that generates a large number of apoptotic vesicles(apoVs).Dysregulated apoptosis has been closely linked to senescence-associated diseases.However,whether apoVs mediate agingrelated bone loss is not clear.In this study,we showed that young MSC-derived apoVs effectively rejuvenated the nuclear abnormalities of aged bone marrow MSCs and restored their impaired self-renewal,osteo-/adipo-genic lineage differentiation capacities via activating autophagy.Mechanistically,apoptotic young MSCs generated and enriched a high level of Ras-related protein 7(Rab7)into apoVs.Subsequently,recipient aged MSCs reused apoV-derived Rab7 to restore autolysosomes formation,thereby contributing to autophagy flux activation and MSC rejuvenation.Moreover,systemic infusion of young MSC-derived apoVs enhanced bone mass,reduced marrow adiposity,and recused the impairment of recipient MSCs in aged mice.Our findings reveal the role of apoVs in rejuvenating aging-MSCs via restoring autolysosome formation and provide a potential approach for treating age-related bone loss.
基金supported by National Natural Science Foundation of China(Grant Number 81472261)Natural Science Foundation of Guangdong Province(Grant Numbers 2014A030310033 and 2015A030313032)+1 种基金Science and Technology Planning Project of Guangdong Province(Grant Number 2013B021800122)Science and Technology Planning Projects of Guangzhou City(Grant Number 201604020044).
文摘Background:Our previous studies demonstrated that eyes absent homolog 4(EYA4),a member of the eye devel-opment-related EYA family in Drosophila,is frequently methylated and silenced in hepatocellular carcinoma(HCC)specimens and associated with shorter survival.The current work aimed to explore the mechanisms through which EYA4 functions as a tumor suppressor in HCC.Methods:Stable EYA4-expressing plasmid(pEYA4)transfectants of the human HCC cell lines Huh-7 and PLC/PRF/5(PLC)were established.Xenografts tumors were established via subcutaneous injection of the stable transfectants into BALB/c nude mice.Tissue samples were obtained from 75 pathologically diagnosed HCC patients.Quantitative real-time polymerase chain reaction,Western blotting and immunohistochemistry were performed to determine the expression of EYA4 in cell lines,xenografts and clinical specimens.The cell proliferation,colony formation,invasiveness and tumor formation of stable transfectants were studied.A gene expression microarray was utilized to screen genes regulated by EYA4 expression.The effect of EYA4 on nuclear factor-κB(NF-κB)/RAS-related protein 1(RAP1)signaling was demonstrated through the co-transfection of pEYA4 and Flag-tagged RAS-related protein 1A gene-expressing plasmid(Flag-RAP1A),functional studies,chromatin immunoprecipitation,immunofluorescence staining and cellular ubiquitination assay.Results:The restoration of EYA4 expression in HCC cell lines suppressed cell proliferation,inhibited clonogenic outgrowth,reduced cell invasion and restrained xenograft tumor growth,and Flag-RAP1A reversed the suppressive effects of pEYA4 in vitro.Activation of NF-κB with tumor necrosis factor-α(TNF-α)increased the binding of p65 to the RAP1A gene promoter and up-regulated RAP1 protein expression.The inhibition of NF-κB with BAY 11-7085 and p65 siRNA successfully blocked TNF-α-induced RAP1 up-regulation.EYA4 antagonized the TNF-α-induced phosphoryla-tion and ubiquitination of inhibitor of NF-κBα(IκBα)as well as the nuclear translocation and transactivation of p65,resulting in repressed NF-κB activity and RAP1 expression.Blocking the serine/threonine phosphatase activity of EYA4 with calyculin A notably abrogated its suppressive effect on NF-κB activity.In addition,EYA4 expression was inversely correlated with IκBα/RAP1 activity in clinical HCC specimens.Conclusion:Our findings provide a functional and mechanistic basis for identifying EYA4 as a bona fide tumor sup-pressor that disrupts aberrant activation of the NF-κB/RAP1 signaling pathway and thus orchestrates a physiological impediment to HCC growth and invasion.
基金Project supported by the National Natural Science Foundation of China(No.81773648)the Zhejiang Provincial Natural Science Foundation of China(No.D19H30001)the Chinese Postdoc Funding(No.2018M630686).
文摘Metastasis is one of the main reasons causing death in cancer patients.It was reported that chemotherapy might induce metastasis.In order to uncover the mechanism of chemotherapy-induced metastasis and find solutions to inhibit treatment-induced metastasis,the relationship between epithelial-mesenchymal transition(EMT)and doxorubicin(DOX)treatment was investigated and a redox-sensitive small interfering RNA(siRNA)delivery system was designed.DOX-related reactive oxygen species(ROS)were found to be responsible for the invasiveness of tumor cells in vitro,causing enhanced EMT and cytoskeleton reconstruction regulated by Ras-related C3 botulinum toxin substrate 1(RAC1).In order to decrease RAC1,a redox-sensitive glycolipid drug delivery system(chitosan-ss-stearylamine conjugate(CSO-ss-SA))was designed to carry siRNA,forming a gene delivery system(CSO-ss-SA/siRNA)downregulating RAC1.CSO-ss-SA/siRNA exhibited an enhanced redox sensitivity compared to nonresponsive complexes in 10 mmol/L glutathione(GSH)and showed a significant safety.CSO-ss-SA/siRNA could effectively transmit siRNA into tumor cells,reducing the expression of RAC1 protein by 38.2%and decreasing the number of tumor-induced invasion cells by 42.5%.When combined with DOX,CSO-ss-SA/siRNA remarkably inhibited the chemotherapy-induced EMT in vivo and enhanced therapeutic efficiency.The present study indicates that RAC1 protein is a key regulator of chemotherapy-induced EMT and CSO-ss-SA/siRNA silencing RAC1 could efficiently decrease the tumor metastasis risk after chemotherapy.
