Viruses are representative of a global threat to agricultural production. Genetic resistance is the preferred strategy for the control of viral infection and against loss of crop yield. Viral protein synthesis require...Viruses are representative of a global threat to agricultural production. Genetic resistance is the preferred strategy for the control of viral infection and against loss of crop yield. Viral protein synthesis requires host cellular factors for translating their viral RNAs, and for regulating their replication and cell to cell systemic movement. Therefore, the viruses are dependent on cellular translation factors. Mutations in the gene encoding eIF4E and eIF4G or their isoforms, eIFiso4 E, eIFiso4 G and eIF2Bβ have been mapped as a source of plant potyvirus while other genus of plant virus recessive resistance genes in many species are originated from these loci. Some of other plant translation factors, such as eIF3,eIF4 A-like helicases, eEF1A and eEF1B, which are required in interacting with viral RNAs and regulating various aspects of the infection cycle,have also been identified. Here, we summarized the mechanisms utilized by RNA viruses of eukaryotic plants and the essential roles of e IFs in virus infection. Moreover, we discussed the potential of e IFs as a target gene in the development of genetic resistance to viruses for crop improvement. This review highlighted newly revealed examples of abnormal translational strategies and provided insights into natural host resistance mechanisms that have been linked to 3 cap-independent translational enhancer activity.展开更多
AIM:To study the expression of eukaryotic translation initiation factor 4E(eIF4E),which is closely correlated with malignant tumors,and its relationship to prognosis in hepatocellular carcinoma. METHODS:Western blotti...AIM:To study the expression of eukaryotic translation initiation factor 4E(eIF4E),which is closely correlated with malignant tumors,and its relationship to prognosis in hepatocellular carcinoma. METHODS:Western blotting was performed to quantify the elF4E protein expression in the normal human liver cell line L02 and the hepatoma cell lines Hep3B, HepG2,and Huh7.Forty-six hepatocellular carcinoma samples with complete clinical data were obtained from Changzheng Hospital during the period of December 2008 to July 2009.The expression of eIF4E in the tumor samples and their adjacent tissues were detected by immunohistochemistry.The relationship between the test results and hepatocellular carcinoma(HCC) prognosis was statistically analysed by using a COX proportional hazard model. RESULTS:Western blotting analysis showed that there were distinct eIF4E protein bands in all three of the hepatoma cell lines.In particular,the HepG2 cell line had the highest level of eIF4E protein expression.The L02 cell group had a low eIF4E expression.Immunohistochemical assay showed that there were 32 cases in which the tumour tissue expression was higher than their adjacent tissues,accounting for 69.57%.There were also 14 cases in which the tumour tissue expression was lower or no significant difference was found, accounting for 30.43%.COX proportional hazards model analysis showed that HCC prognosis was related to the depth of invasion,the overexpression of eIF4E and p53, possibly as independent HCC prognostic predictors. CONCLUSION:In summary,eIF4E expression is associated with liver cancer,and patients with high eIF4E expression levels have a higher risk of recurrence.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
Characterization of genes related to sweetpotato viral disease resistance is critical for understanding plant-pathogen interactions, especially with feathery mottle virus infection. For example, genes encoding eukaryo...Characterization of genes related to sweetpotato viral disease resistance is critical for understanding plant-pathogen interactions, especially with feathery mottle virus infection. For example, genes encoding eukaryotic translation initiation factor (eIF)4E, its isoforms, eIF(iso)4E, and the cap-binding protein (CBP) in plants, have been implicated in viral infections aside from their importance in protein synthesis. Full-length cDNA encoding these putative eIF targets from susceptible/resistant and unknown hexaploid sweetpotato (Ipomoea batatas L. Lam) were amplified based on primers designed from the diploid wild-type relative Ipomoea trifida consensus sequences, and designated IbeIF4E, IbeIF(iso)4E and IbCBP. Comparative analyses following direct-sequencing of PCR-amplified cDNAs versus the cloned cDNA sequences identified multiple homeoalleles: one to four IbeIF4E, two to three IbeIF(iso)4E, and two IbCBP within all cultivars tested. Open reading frames were in the length of 696 bp IbeIF4E, 606 bp IbeIF(iso)4E, and 675 bp IbCBP. The encoded single polypeptide lengths were 232, 202, and 225 amino acids for IbeIF4E, IbeIF(iso)4E, and IbCBP, with a calculated protein molecular mass of 26 kDa, 22.8 kDa, and 25.8 kDa, while their theoretical isoelectric points were 5.1, 5.57, and 6.6, respectively. Although the homeoalleles had similar sequence lengths, single nucleotide polymorphisms and multi-allelic variations were detected within the coding sequences. The multi-sequence alignment performed revealed a 66.9% - 96.7% sequence similarity between the predicted amino acid sequences obtained from the homeoalleles and closely related species. Furthermore, phylogenetic analysis revealed ancestral relationships between the eIF4E homeoalleles and other species. The outcome herein on the eIF4E superfamily and its correlation in sequence variations suggest opportunities to decipher the role of eIF4E in hexaploid sweetpotato feathery mottle virus infection.展开更多
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
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
基金The authors thank Mr.Tomas Maher from the Department of Biology at the Pennsylvania State University for language editing.This work is supported by the National Natural Science Foundation of Zhejiang Province(Grant No.LZ20C150002)and the National Natural Science Foundation of China(Grant No.31872095).
文摘Viruses are representative of a global threat to agricultural production. Genetic resistance is the preferred strategy for the control of viral infection and against loss of crop yield. Viral protein synthesis requires host cellular factors for translating their viral RNAs, and for regulating their replication and cell to cell systemic movement. Therefore, the viruses are dependent on cellular translation factors. Mutations in the gene encoding eIF4E and eIF4G or their isoforms, eIFiso4 E, eIFiso4 G and eIF2Bβ have been mapped as a source of plant potyvirus while other genus of plant virus recessive resistance genes in many species are originated from these loci. Some of other plant translation factors, such as eIF3,eIF4 A-like helicases, eEF1A and eEF1B, which are required in interacting with viral RNAs and regulating various aspects of the infection cycle,have also been identified. Here, we summarized the mechanisms utilized by RNA viruses of eukaryotic plants and the essential roles of e IFs in virus infection. Moreover, we discussed the potential of e IFs as a target gene in the development of genetic resistance to viruses for crop improvement. This review highlighted newly revealed examples of abnormal translational strategies and provided insights into natural host resistance mechanisms that have been linked to 3 cap-independent translational enhancer activity.
文摘AIM:To study the expression of eukaryotic translation initiation factor 4E(eIF4E),which is closely correlated with malignant tumors,and its relationship to prognosis in hepatocellular carcinoma. METHODS:Western blotting was performed to quantify the elF4E protein expression in the normal human liver cell line L02 and the hepatoma cell lines Hep3B, HepG2,and Huh7.Forty-six hepatocellular carcinoma samples with complete clinical data were obtained from Changzheng Hospital during the period of December 2008 to July 2009.The expression of eIF4E in the tumor samples and their adjacent tissues were detected by immunohistochemistry.The relationship between the test results and hepatocellular carcinoma(HCC) prognosis was statistically analysed by using a COX proportional hazard model. RESULTS:Western blotting analysis showed that there were distinct eIF4E protein bands in all three of the hepatoma cell lines.In particular,the HepG2 cell line had the highest level of eIF4E protein expression.The L02 cell group had a low eIF4E expression.Immunohistochemical assay showed that there were 32 cases in which the tumour tissue expression was higher than their adjacent tissues,accounting for 69.57%.There were also 14 cases in which the tumour tissue expression was lower or no significant difference was found, accounting for 30.43%.COX proportional hazards model analysis showed that HCC prognosis was related to the depth of invasion,the overexpression of eIF4E and p53, possibly as independent HCC prognostic predictors. CONCLUSION:In summary,eIF4E expression is associated with liver cancer,and patients with high eIF4E expression levels have a higher risk of recurrence.
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.
文摘Characterization of genes related to sweetpotato viral disease resistance is critical for understanding plant-pathogen interactions, especially with feathery mottle virus infection. For example, genes encoding eukaryotic translation initiation factor (eIF)4E, its isoforms, eIF(iso)4E, and the cap-binding protein (CBP) in plants, have been implicated in viral infections aside from their importance in protein synthesis. Full-length cDNA encoding these putative eIF targets from susceptible/resistant and unknown hexaploid sweetpotato (Ipomoea batatas L. Lam) were amplified based on primers designed from the diploid wild-type relative Ipomoea trifida consensus sequences, and designated IbeIF4E, IbeIF(iso)4E and IbCBP. Comparative analyses following direct-sequencing of PCR-amplified cDNAs versus the cloned cDNA sequences identified multiple homeoalleles: one to four IbeIF4E, two to three IbeIF(iso)4E, and two IbCBP within all cultivars tested. Open reading frames were in the length of 696 bp IbeIF4E, 606 bp IbeIF(iso)4E, and 675 bp IbCBP. The encoded single polypeptide lengths were 232, 202, and 225 amino acids for IbeIF4E, IbeIF(iso)4E, and IbCBP, with a calculated protein molecular mass of 26 kDa, 22.8 kDa, and 25.8 kDa, while their theoretical isoelectric points were 5.1, 5.57, and 6.6, respectively. Although the homeoalleles had similar sequence lengths, single nucleotide polymorphisms and multi-allelic variations were detected within the coding sequences. The multi-sequence alignment performed revealed a 66.9% - 96.7% sequence similarity between the predicted amino acid sequences obtained from the homeoalleles and closely related species. Furthermore, phylogenetic analysis revealed ancestral relationships between the eIF4E homeoalleles and other species. The outcome herein on the eIF4E superfamily and its correlation in sequence variations suggest opportunities to decipher the role of eIF4E in hexaploid sweetpotato feathery mottle virus infection.
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.
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.
