Eukaryotic initiation factor 5A2(eIF5A2),as one of the two isoforms in the family,is reported to be a novel oncogenic protein that is involved in multiple aspects of many types of human cancer.Overexpression or gene a...Eukaryotic initiation factor 5A2(eIF5A2),as one of the two isoforms in the family,is reported to be a novel oncogenic protein that is involved in multiple aspects of many types of human cancer.Overexpression or gene amplification of EIF5A2 has been demonstrated in many cancers.Accumulated evidence shows that eIF5A2 initiates tumor formation,enhances cancer cell growth,increases cancer cell metastasis,and promotes treatment resistance through multiple means,including inducing epithelial–mesenchymal transition,cytoskeletal rearrangement,angiogenesis,and metabolic reprogramming.Expression of eIF5A2 in cancer correlates with poor survival,advanced disease stage,as well as metastasis,suggesting that eIF5A2 function is crucial for tumor development and maintenance but not for normal tissue homeostasis.All these studies suggest that eIF5A2 is a useful biomarker in the prediction of cancer prognosis and serves as an anticancer molecular target.This review focuses on the expression,subcellular localization,post-translational modifications,and regulatory networks of eIF5A2,as well as its biochemical functions and evolving clinical applications in cancer,especially in human digestive system neoplasms.展开更多
AIM: To study the localization and function of a eukaryotic initiation factor 2 (eIF2α)-associated 67-kDa glycoprotein (p67).METHODS: Immunofluorescence staining,35S-Met/Cys metabolic labeling,Western blotting analys...AIM: To study the localization and function of a eukaryotic initiation factor 2 (eIF2α)-associated 67-kDa glycoprotein (p67).METHODS: Immunofluorescence staining,35S-Met/Cys metabolic labeling,Western blotting analysis,sucrose gradient centrifugation and high speed centrifugation were used to determine the localization of proteins in transiently transfected COS-1 cells.Transient co-transfection followed by co-immunoprecipitation was used to study the interaction between p67 and double-stranded RNA (dsRNA)-dependent protein kinase (PKR).Wheat germ agglutinin agarose beads were used to absorb glycosylated proteins.In vivo 32P-labeling followed by immunoprecipitation and Western blotting were used to measure PKR autophosphorylation,eIF2α phosphorylation,and p67 expression in normal and breast cancer cells.RESULTS: The image from immunofluorescence staining showed that p67 was overexpressed in the cytosol but not in the nucleus.In a sucrose gradient,approxi-mately 30% of the overexpressed p67 was bound with ribosomes.p67 interacted with the kinase domain,butnot the dsRNA-binding domains of PKR.Only the glycosylated p67 was associated with the ribosome,and p67 did not compete with PKR for ribosome binding.In breast cancer cells,there was increased autophosphorylation of PKR but no phosphorylation of eIF2α,compared with normal breast cells.α The ratio of glycosylated/deglycosylated p67 was altered in breast cancer cells.CONCLUSION: Glycosylation of p67 is required for its ribosomal association and can potentially inhibit PKR via interaction with the kinase domain of PKR.展开更多
The relationship between angiogenesis and eukaryotic translation initiation factor 4E （EIF4E） expression level in non Hodgkin lymphoma （NHL） was studied. Mean microvessel density （MVD） and EIF4E were detected in...The relationship between angiogenesis and eukaryotic translation initiation factor 4E （EIF4E） expression level in non Hodgkin lymphoma （NHL） was studied. Mean microvessel density （MVD） and EIF4E were detected in 52 lymph node samples paraffin sections of patients with newly diagnosed NHL by the way of immunohistochemistry. Antisense EIF4E cDNA was cloned into plasmid pcDNA3.1 （＋） and transfected into Raji cells. A series of angiogenesis related factors,including vascular endothelial growth factor （VEGF）, matrix metalloproteinases 9 （MMP-9） and tissue inhibitor of metalloproteinases-2 （TIMP-2） proteins were detected by Western blot. The results showed that： （1） The Expression of EIF4E and MVD was higher in aggressive lymphomas than in indolent lymphomas（P〈0.05）and the expression of EIF4E was positively correlated with MVD in lymph node of NHL（r=0. 695, P〈0.01）. （2） Antisense EIF4E eukaryocytic expression vector （pcDNA3. 1-EIF4Eas） was constructed successfully. （3） EIF4E, VEGF and MMP-9 were expressed at high levels in Raji cells as compared to normal human peripheral blood monocular cells （NHPMC）, and blockage of EIF4E expression brought down the expression of VEGF and MMP-9. However, TIMP-2 was undetectable in Rail cells, although a moderate level of TIMP-2 was detected in NHPMC. It was concluded that the increased EIF4E expression was associated with aggressive property of NHL.展开更多
Vanishing white matter disease （VWM）, a human atitosomal recessive inherited leukoencephalopathy, is due to mutations in eukaryotic initiation factor 2B （elF2B）. elF2B is responsible for tile initiation of protein...Vanishing white matter disease （VWM）, a human atitosomal recessive inherited leukoencephalopathy, is due to mutations in eukaryotic initiation factor 2B （elF2B）. elF2B is responsible for tile initiation of protein synthesis by its guanine nucleotide exchange lhctor （GEF） activity. Mutations ofelF2B impair GEF activity at different degree. Previous studies implied improperly activated unlblded protein response （UPR） and endoplasmic reticulum stress （ERS） participated in the pathogenesis ofVWM. Autophagy relieves endoplasmic reticulum load by eliminating the unfolded protein. It is still unknown the effects of genotypes on the pathogenesis. In this work, UPR and autophagy flux were analyzed with different mutational types. Methods： ERS tolerance, reflected by apoptosis and cell viability, was detected in human oligodendrocyte cell line transfected with the wild type, or different mutations of p. Argl 13 His, p. Arg269＊ or p. Ser610-Asp613del in el F2 Be. A representative U PR-PERK component of activating transcription lhctor 4 （ATF4） was measured under the basal condition and ERS induction. Autophagy was analyzed the flux in the presence of lysosomal inhibitors. Results： The degree of ERS tolerance varied in different genotypes. The truncated or deletion mutant showed prominent apoptosis cell viability declination after ERS induction. The most seriously damaged GEF activity ofp. Arg269＊ group underwent spontaneous apoptosis. The truncated or deletion mutant showed elevated ATF4 under basal as well as ERS condition. Decreased expression of LC3-1 and LC3-11 in the mutants reflected an impaired autophagy flux, which was more obvious in the truncated or deletion mutants alter ERS induction. Conclusions： GEF activities in dilt;erent genotypes could influence the cell ERS tolerance as well as compensatory pathways of UPR and autophagy. Oligodendrocytes with truncated or deletion inutants showed less tolerable to ERS.展开更多
Eukaryotic translation initiation factor eIF2B,the guanine nucleotide exchange factor(GEF)for eIF2,catalyzes conversion of eIF2·GDP to eIF2·GTP.The eIF2B is composed of five subunits,α,β,γ,δandε,within ...Eukaryotic translation initiation factor eIF2B,the guanine nucleotide exchange factor(GEF)for eIF2,catalyzes conversion of eIF2·GDP to eIF2·GTP.The eIF2B is composed of five subunits,α,β,γ,δandε,within which theεsubunit is responsible for catalyzing the guanine exchange reaction.Here we present the crystal structure of the C-terminal domain of human eIF2Bε(eIF2Bε-CTD)at 2.0-Åresolution.The structure resembles a HEAT motif and three charge-rich areas on its surface can be identified.When compared to yeast eIF2Bε-CTD,one area involves highly conserved AA boxes while the other two are only partially conserved.In addition,the previously reported mutations in human eIF2Bε-CTD,which are related to the loss of the GEF activity and human VWM disease,have been discussed.Based on the structure,most of such mutations tend to destabilize the HEAT motif.展开更多
Objective The expression levels of histone deacetylase 2(HDAC2),eukaryotic initiation factor 5(eIF5),and eukaryotic initiation factor 6(eIF6),and relationship between HDAC2 and eIF5 or eIF6 in lung cancer tissues were...Objective The expression levels of histone deacetylase 2(HDAC2),eukaryotic initiation factor 5(eIF5),and eukaryotic initiation factor 6(eIF6),and relationship between HDAC2 and eIF5 or eIF6 in lung cancer tissues were investigated,in order to charify the relationship between HDAC2 and the prognosis of lung cancer patients and its influence on the expression of eIF5 and eIF6.Methods The expression of HDAC2,eIF5,and eIF6 in lung cancer tissues was detected by quantitative reverse transcription polymerase chain reaction.The expression correlation between HDAC2 and eIF5 or eIF6 was tested using a t test.The correlation between HDAC2 and eIF5 or eIF6 was analyzed using the TCGA database.The identified cells were constructed with small interfering siRNA and HDAC2 overexpression plasmid.The proliferation and migration ability of the identified cells was investigated by CCK8 and Transwell assays,respectively.Results HDAC2,eIF5,and eIF6 were overexpressed in lung cancer tissues,and HDAC2 expression level was negatively correlated with the prognosis of lung cancer patients.HDAC2 expression level was positively correlated with eIF5 and eIF6 expression levels.HDAC2 could regulate the expression of eIF5 and eIF6.The regulation of proliferation and invasion of lung cancer cells by HDAC2 depended on eIF5 and eIF6.Conclusion HDAC2,eIF5,and eIF6 were closely related with lung cancer tumorigenesis,which might be potential biological markers and therapeutic targets for lung cancer.展开更多
The retinal ganglion cells of the optic nerve have a limited capacity for self-repair after injury.Valproate is a histone deacetylase inhibitor and multitarget drug,which has been demonstrated to protect retinal neuro...The retinal ganglion cells of the optic nerve have a limited capacity for self-repair after injury.Valproate is a histone deacetylase inhibitor and multitarget drug,which has been demonstrated to protect retinal neurons.In this study,we established rat models of optic nerve-crush injury and injected valproate into the vitreous cavity immediately after modeling.We evaluated changes in the ultrastructure morphology of the endoplasmic reticulum of retinal ganglion cells over time via transmission electron microscope.Immunohistochemistry and western blot assay revealed that valproate upregulated the expression of the endoplasmic reticulum stress marker glucose-regulated protein 78 and downregulated the expression of transcription factor C/EBP homologous protein,phosphorylated eukaryotic translation initiation factor 2α,and caspase-12 in the endoplasmic reticulum of retinal ganglion cells.These findings suggest that valproate reduces apoptosis of retinal ganglion cells in the rat after optic nerve-crush injury by attenuating phosphorylated eukaryotic translation initiation factor 2α-C/EBP homologous protein signaling and caspase-12 activation during endoplasmic reticulum stress.These findings represent a newly discovered mechanism that regulates how valproate protects neurons.展开更多
基金Supported by Natural Science Foundation of Hubei Province,No.2016CFB596Wuhan City Medical Research Project,Nos.WX15B14and WX17Q39Hubei Province Scientific Research Project,No.WJ2015MB137
文摘Eukaryotic initiation factor 5A2(eIF5A2),as one of the two isoforms in the family,is reported to be a novel oncogenic protein that is involved in multiple aspects of many types of human cancer.Overexpression or gene amplification of EIF5A2 has been demonstrated in many cancers.Accumulated evidence shows that eIF5A2 initiates tumor formation,enhances cancer cell growth,increases cancer cell metastasis,and promotes treatment resistance through multiple means,including inducing epithelial–mesenchymal transition,cytoskeletal rearrangement,angiogenesis,and metabolic reprogramming.Expression of eIF5A2 in cancer correlates with poor survival,advanced disease stage,as well as metastasis,suggesting that eIF5A2 function is crucial for tumor development and maintenance but not for normal tissue homeostasis.All these studies suggest that eIF5A2 is a useful biomarker in the prediction of cancer prognosis and serves as an anticancer molecular target.This review focuses on the expression,subcellular localization,post-translational modifications,and regulatory networks of eIF5A2,as well as its biochemical functions and evolving clinical applications in cancer,especially in human digestive system neoplasms.
文摘AIM: To study the localization and function of a eukaryotic initiation factor 2 (eIF2α)-associated 67-kDa glycoprotein (p67).METHODS: Immunofluorescence staining,35S-Met/Cys metabolic labeling,Western blotting analysis,sucrose gradient centrifugation and high speed centrifugation were used to determine the localization of proteins in transiently transfected COS-1 cells.Transient co-transfection followed by co-immunoprecipitation was used to study the interaction between p67 and double-stranded RNA (dsRNA)-dependent protein kinase (PKR).Wheat germ agglutinin agarose beads were used to absorb glycosylated proteins.In vivo 32P-labeling followed by immunoprecipitation and Western blotting were used to measure PKR autophosphorylation,eIF2α phosphorylation,and p67 expression in normal and breast cancer cells.RESULTS: The image from immunofluorescence staining showed that p67 was overexpressed in the cytosol but not in the nucleus.In a sucrose gradient,approxi-mately 30% of the overexpressed p67 was bound with ribosomes.p67 interacted with the kinase domain,butnot the dsRNA-binding domains of PKR.Only the glycosylated p67 was associated with the ribosome,and p67 did not compete with PKR for ribosome binding.In breast cancer cells,there was increased autophosphorylation of PKR but no phosphorylation of eIF2α,compared with normal breast cells.α The ratio of glycosylated/deglycosylated p67 was altered in breast cancer cells.CONCLUSION: Glycosylation of p67 is required for its ribosomal association and can potentially inhibit PKR via interaction with the kinase domain of PKR.
文摘The relationship between angiogenesis and eukaryotic translation initiation factor 4E （EIF4E） expression level in non Hodgkin lymphoma （NHL） was studied. Mean microvessel density （MVD） and EIF4E were detected in 52 lymph node samples paraffin sections of patients with newly diagnosed NHL by the way of immunohistochemistry. Antisense EIF4E cDNA was cloned into plasmid pcDNA3.1 （＋） and transfected into Raji cells. A series of angiogenesis related factors,including vascular endothelial growth factor （VEGF）, matrix metalloproteinases 9 （MMP-9） and tissue inhibitor of metalloproteinases-2 （TIMP-2） proteins were detected by Western blot. The results showed that： （1） The Expression of EIF4E and MVD was higher in aggressive lymphomas than in indolent lymphomas（P〈0.05）and the expression of EIF4E was positively correlated with MVD in lymph node of NHL（r=0. 695, P〈0.01）. （2） Antisense EIF4E eukaryocytic expression vector （pcDNA3. 1-EIF4Eas） was constructed successfully. （3） EIF4E, VEGF and MMP-9 were expressed at high levels in Raji cells as compared to normal human peripheral blood monocular cells （NHPMC）, and blockage of EIF4E expression brought down the expression of VEGF and MMP-9. However, TIMP-2 was undetectable in Rail cells, although a moderate level of TIMP-2 was detected in NHPMC. It was concluded that the increased EIF4E expression was associated with aggressive property of NHL.
基金grants from the Natural Science Foundation of China，National Key Technology R and D Program，Key Laboratory Program of Ministry of Education
文摘Vanishing white matter disease （VWM）, a human atitosomal recessive inherited leukoencephalopathy, is due to mutations in eukaryotic initiation factor 2B （elF2B）. elF2B is responsible for tile initiation of protein synthesis by its guanine nucleotide exchange lhctor （GEF） activity. Mutations ofelF2B impair GEF activity at different degree. Previous studies implied improperly activated unlblded protein response （UPR） and endoplasmic reticulum stress （ERS） participated in the pathogenesis ofVWM. Autophagy relieves endoplasmic reticulum load by eliminating the unfolded protein. It is still unknown the effects of genotypes on the pathogenesis. In this work, UPR and autophagy flux were analyzed with different mutational types. Methods： ERS tolerance, reflected by apoptosis and cell viability, was detected in human oligodendrocyte cell line transfected with the wild type, or different mutations of p. Argl 13 His, p. Arg269＊ or p. Ser610-Asp613del in el F2 Be. A representative U PR-PERK component of activating transcription lhctor 4 （ATF4） was measured under the basal condition and ERS induction. Autophagy was analyzed the flux in the presence of lysosomal inhibitors. Results： The degree of ERS tolerance varied in different genotypes. The truncated or deletion mutant showed prominent apoptosis cell viability declination after ERS induction. The most seriously damaged GEF activity ofp. Arg269＊ group underwent spontaneous apoptosis. The truncated or deletion mutant showed elevated ATF4 under basal as well as ERS condition. Decreased expression of LC3-1 and LC3-11 in the mutants reflected an impaired autophagy flux, which was more obvious in the truncated or deletion mutants alter ERS induction. Conclusions： GEF activities in dilt;erent genotypes could influence the cell ERS tolerance as well as compensatory pathways of UPR and autophagy. Oligodendrocytes with truncated or deletion inutants showed less tolerable to ERS.
基金This work was supported by the National Programs for High Technology Research and Development Program(863 Program)(Grant No.2006AA02A316)the National Basic Research Program(973 Program)(Grant Nos.2004CB520801,2006CB910903,2007CB914304,2009CB825501 and 2010CB912301)+1 种基金the Ministry of Science and Technology,National Natural Science Foundation of China(Grant Nos.30721003 and 30870484)the Chinese Academy of Sciences(Grant No.KSCX2-YW-R61).
文摘Eukaryotic translation initiation factor eIF2B,the guanine nucleotide exchange factor(GEF)for eIF2,catalyzes conversion of eIF2·GDP to eIF2·GTP.The eIF2B is composed of five subunits,α,β,γ,δandε,within which theεsubunit is responsible for catalyzing the guanine exchange reaction.Here we present the crystal structure of the C-terminal domain of human eIF2Bε(eIF2Bε-CTD)at 2.0-Åresolution.The structure resembles a HEAT motif and three charge-rich areas on its surface can be identified.When compared to yeast eIF2Bε-CTD,one area involves highly conserved AA boxes while the other two are only partially conserved.In addition,the previously reported mutations in human eIF2Bε-CTD,which are related to the loss of the GEF activity and human VWM disease,have been discussed.Based on the structure,most of such mutations tend to destabilize the HEAT motif.
基金supported by the Startup Fund for scientific research,Fujian Medical University(No.2018QH1114)Fujian Health and Healthy Middle-aged and Young Backbone Talents Training Project(No.2019-ZQN-4).
文摘Objective The expression levels of histone deacetylase 2(HDAC2),eukaryotic initiation factor 5(eIF5),and eukaryotic initiation factor 6(eIF6),and relationship between HDAC2 and eIF5 or eIF6 in lung cancer tissues were investigated,in order to charify the relationship between HDAC2 and the prognosis of lung cancer patients and its influence on the expression of eIF5 and eIF6.Methods The expression of HDAC2,eIF5,and eIF6 in lung cancer tissues was detected by quantitative reverse transcription polymerase chain reaction.The expression correlation between HDAC2 and eIF5 or eIF6 was tested using a t test.The correlation between HDAC2 and eIF5 or eIF6 was analyzed using the TCGA database.The identified cells were constructed with small interfering siRNA and HDAC2 overexpression plasmid.The proliferation and migration ability of the identified cells was investigated by CCK8 and Transwell assays,respectively.Results HDAC2,eIF5,and eIF6 were overexpressed in lung cancer tissues,and HDAC2 expression level was negatively correlated with the prognosis of lung cancer patients.HDAC2 expression level was positively correlated with eIF5 and eIF6 expression levels.HDAC2 could regulate the expression of eIF5 and eIF6.The regulation of proliferation and invasion of lung cancer cells by HDAC2 depended on eIF5 and eIF6.Conclusion HDAC2,eIF5,and eIF6 were closely related with lung cancer tumorigenesis,which might be potential biological markers and therapeutic targets for lung cancer.
基金supported by the National Natural Science Foundation of China,Nos.30772368(to DH),81371034(to XH)the Key Project of Natural Science Foundation of Shaanxi Province,No.2017JZ025(to DH).
文摘The retinal ganglion cells of the optic nerve have a limited capacity for self-repair after injury.Valproate is a histone deacetylase inhibitor and multitarget drug,which has been demonstrated to protect retinal neurons.In this study,we established rat models of optic nerve-crush injury and injected valproate into the vitreous cavity immediately after modeling.We evaluated changes in the ultrastructure morphology of the endoplasmic reticulum of retinal ganglion cells over time via transmission electron microscope.Immunohistochemistry and western blot assay revealed that valproate upregulated the expression of the endoplasmic reticulum stress marker glucose-regulated protein 78 and downregulated the expression of transcription factor C/EBP homologous protein,phosphorylated eukaryotic translation initiation factor 2α,and caspase-12 in the endoplasmic reticulum of retinal ganglion cells.These findings suggest that valproate reduces apoptosis of retinal ganglion cells in the rat after optic nerve-crush injury by attenuating phosphorylated eukaryotic translation initiation factor 2α-C/EBP homologous protein signaling and caspase-12 activation during endoplasmic reticulum stress.These findings represent a newly discovered mechanism that regulates how valproate protects neurons.
