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
In eukaryotic cells, protein synthesis is a complex and multi-step process that has several mechanisms to start the translation including cap-dependent and cap-independent initiation. The translation control of eukary...In eukaryotic cells, protein synthesis is a complex and multi-step process that has several mechanisms to start the translation including cap-dependent and cap-independent initiation. The translation control of eukaryotic gene expression occurs principally at the initiation step. In this context, it is critical that the eukaryotic translation initiation factor eIF4E bind to the 7-methylguanosine (m7G) cap present at the 5'- UTRs of most eukaryotic mRNAs. Combined with other initiation factors, elF4E mediates the mRNA recruitment on ribosomes to start the translation. Moreover, the eIF4E nuclear bodies are involved in the export of specific mRNAs from the nucleus to the cytoplasm. In this review, we focus on the elF4E structure and its physiological functions, and describe the role of eIF4E in cancer development and progression and the current therapeutic strategies to target eIF4E.展开更多
Studies over the past three years have substantially expanded the involvements of eukaryotic initiation factor 3 (eIF3) in messenger RNA (mRNA) translation. It now appears that this multi-subunit complex is involved i...Studies over the past three years have substantially expanded the involvements of eukaryotic initiation factor 3 (eIF3) in messenger RNA (mRNA) translation. It now appears that this multi-subunit complex is involved in every possible form of mRNA translation, controlling every step of protein synthesis from initiation to elongation, termination, and quality control in positive as well as negative fashion. Through the study of eIF3, we are beginning to appreciate protein synthesis as a highly integrated process coordinating protein production with protein folding, subcellular targeting, and degradation. At the same time, eIF3 subunits appear to have specific functions that probably vary between different tissues and individual cells. Considering the broad functions of eIF3 in protein homeostasis, it comes as little surprise that eIF3 is increasingly implicated in major human diseases and first attempts at therapeutically targeting eIF3 have been undertaken. Much remains to be learned, however, about subunit- and tissue-specific functions of eIF3 in protein synthesis and disease and their regulation by environmental conditions and post-translational modifications.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
tRNA-derived small RNAs(tsRNAs)are novel non-coding RNAs that are involved in the occurrence and progression of diverse diseases.However,their exact presence and function in hepatocellular carcinoma(HCC)remain unclear...tRNA-derived small RNAs(tsRNAs)are novel non-coding RNAs that are involved in the occurrence and progression of diverse diseases.However,their exact presence and function in hepatocellular carcinoma(HCC)remain unclear.Here,differentially expressed tsRNAs in HCC were profiled.A novel tsRNA,tRNAGln-TTG derived 5′-tiRNA-Gln,is significantly downregulated,and its expression level is correlated with progression in patients.In HCC cells,5′-tiRNA-Gln overexpression impaired the proliferation,migration,and invasion in vitro and in vivo,while 5′-tiRNA-Gln knockdown yielded opposite results.5′-tiRNA-Gln exerted its function by binding eukaryotic initiation factor 4A-I(EIF4A1),which unwinds complex RNA secondary structures during translation initiation,causing the partial inhibition of translation.The suppressed downregulated proteins include ARAF,MEK1/2 and STAT3,causing the impaired signaling pathway related to HCC progression.Furthermore,based on the construction of a mutant 5′-tiRNA-Gln,the sequence of forming intramolecular G-quadruplex structure is crucial for 5′-tiRNA-Gln to strongly bind EIF4A1 and repress translation.Clinically,5′-tiRNA-Gln expression level is negatively correlated with ARAF,MEK1/2,and STAT3 in HCC tissues.Collectively,these findings reveal that 5′-tiRNA-Gln interacts with EIF4A1 to reduce related mRNA binding through the intramolecular Gquadruplex structure,and this process partially inhibits translation and HCC progression.展开更多
Ras homolog enriched in brain(Rheb) is a small GTPase that activates mammalian target of rapamycin complex 1(mTORC1).Previous studies have shown that constitutively active Rheb can enhance the regeneration of sensory ...Ras homolog enriched in brain(Rheb) is a small GTPase that activates mammalian target of rapamycin complex 1(mTORC1).Previous studies have shown that constitutively active Rheb can enhance the regeneration of sensory axons after spinal cord injury by activating downstream effectors of mTOR.S6K1 and4E-BP1 are important downstream effectors of mTORC1.In this study,we investigated the role of Rheb/mTOR and its downstream effectors S6K1 and 4E-BP1in the protection of retinal ganglion cells.We transfected an optic nerve crush mouse model with adeno-associated viral 2-mediated constitutively active Rheb and observed the effects on retinal ganglion cell survival and axon regeneration.We found that overexpression of constitutively active Rheb promoted survival of retinal ganglion cells in the acute(14 days) and chronic(21 and 42 days) stages of injury.We also found that either co-expression of the dominant-negative S6K1mutant or the constitutively active 4E-BP1 mutant together with constitutively active Rheb markedly inhibited axon regeneration of retinal ganglion cells.This suggests that mTORC1-mediated S6K1 activation and 4E-BP1 inhibition were necessary components for constitutively active Rheb-induced axon regeneration.However,only S6K1 activation,but not 4E-BP1 knockdown,induced axon regeneration when applied alone.Furthermore,S6K1 activation promoted the survival of retinal ganglion cells at 14 days post-injury,whereas 4E-BP1 knockdown unexpectedly slightly decreased the survival of retinal ganglion cells at 14 days postinjury.Ove rexpression of constitutively active 4E-BP1 increased the survival of retinal ganglion cells at 14 days post-injury.Likewise,co-expressing constitutively active Rheb and constitutively active 4E-BP1 markedly increased the survival of retinal ganglion cells compared with overexpression of constitutively active Rheb alone at 14 days post-injury.These findings indicate that functional 4E-BP1 and S6K1 are neuroprotective and that 4E-BP1 may exert protective effects through a pathway at least partially independent of Rhe b/mTOR.Together,our results show that constitutively active Rheb promotes the survival of retinal ganglion cells and axon regeneration through modulating S6K1 and 4E-BP1 activity.Phosphorylated S6K1 and 4E-BP1 promote axon regeneration but play an antagonistic role in the survival of retinal ganglion cells.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
Objective Cisplatin(CDDP)-based chemotherapy is a first-line,drug regimen for muscle-invasive bladder cancer(BC)and metastatic bladder cancer.Clinically,resistance to CDDP restricts the clinical benefit of some bladde...Objective Cisplatin(CDDP)-based chemotherapy is a first-line,drug regimen for muscle-invasive bladder cancer(BC)and metastatic bladder cancer.Clinically,resistance to CDDP restricts the clinical benefit of some bladder cancer patients.AT-rich interaction domain 1A(ARID1A)gene mutation occurs frequently in bladder cancer;however,the role of CDDP sensitivity in BC has not been studied.Methods We established ARID1A knockout BC cell lines using CRISPR/Cas9 technology.IC50 determination,flow cytometry analysis of apoptosis,and tumor xenograft assays were performed to verify changes in the CDDP sensitivity of BC cells losing ARID1A.qRT-PCR,Western blotting,RNA interference,bioinformatic analysis,and ChIP-qPCR analysis were performed to further explore the potential mechanism of ARID1A inactivation in CDDP sensitivity in BC.Results It was found that ARID1A inactivation was associated with CDDP resistance in BC cells.Mechanically,loss of ARID1A promoted the expression of eukaryotic translation initiation factor 4A3(EIF4A3)through epigenetic regulation.Increased expression of EIF4A3 promoted the expression of hsa_circ_0008399(circ0008399),a novel circular RNA(circRNA)identified in our previous study,which,to some extent,showed that ARID1A deletion caused CDDP resistance through the inhibitory effect of circ0008399 on the apoptosis of BC cells.Importantly,EIF4A3-IN-2 specifically inhibited the activity of EIF4A3 to reduce circ0008399 production and restored the sensitivity of ARID1A inactivated BC cells to CDDP.Conclusion Our research deepens the understanding of the mechanisms of CDDP resistance in BC and elucidates a potential strategy to improve the efficacy of CDDP in BC patients with ARID1A deletion through combination therapy targeting EIF4A3.展开更多
BACKGROUND Breast cancer(BC) remains a public health problem. Tamoxifen(TAM) resistance has caused great difficulties for treatment of BC patients. Eukaryotic translation initiation factor 4E binding protein 1(EIF4EBP...BACKGROUND Breast cancer(BC) remains a public health problem. Tamoxifen(TAM) resistance has caused great difficulties for treatment of BC patients. Eukaryotic translation initiation factor 4E binding protein 1(EIF4EBP1) plays critical roles in the tumorigenesis and progression of BC. However, the expression and mechanism of EIF4EBP1 in determining the efficacy of TAM therapy in BC patients are still unclear.AIM To investigate the expression and functions of EIF4EBP1 in determining the efficacy of TAM therapy in BC patients.METHODS High-throughput sequencing data of breast tumors were downloaded from the Gene Expression Omnibus database. Differential gene expression analysis identified EIF4EBP1 to be significantly upregulated in cancer tissues. Its prognostic value was analyzed. The biological function and related pathways of EIF4EBP1 was analyzed. Subsequently, the expression of EIF4EBP1 was determined by real-time reverse transcription polymerase chain reaction and western blotting. Cell Counting Kit-8 assays, colony formation assay and wound healing assay were used to understand the phenotypes of function of EIF4EBP1.RESULTS EIF4EBP1 was upregulated in the TAM-resistant cells, and EIF4EBP1 was related to the prognosis of BC patients. Gene Set Enrichment Analysis showed that EIF4EBP1 might be involved in Hedgehog signaling pathways. Decreasing the expression of EIF4EBP1 could reverse TAM resistance, whereas overexpression of EIF4EBP1 promoted TAM resistance.CONCLUSION This study indicated that EIF4EBP1 was overexpressed in the BC and TAM-resistant cell line, which increased cell proliferation, invasion, migration and TAM resistance in BC cells.展开更多
[Objectives] To study the therapeutic effect and mechanism of New Maixian Powder on ulcerative colitis( UC) rats through observing its regulatory effect on the protein kinase R-like endoplasmic reticulum kinase( PERK)...[Objectives] To study the therapeutic effect and mechanism of New Maixian Powder on ulcerative colitis( UC) rats through observing its regulatory effect on the protein kinase R-like endoplasmic reticulum kinase( PERK)/eukaryotic translation initiation factor-2α( e IF-2α)/nuclear transcription factor-kappa B( NF-κB) signaling pathway. [Methods]First,60 SD rats were randomly divided into normal group,model group,mesalazine group,and New Maixian Powder low,medium and high dose groups,10 rats each group. Then,dextran sulfate sodium( DSS) was used to induce UC rats. The mesalazine group was given 0. 42 g/( kg·d) of mesalazine sustained-release granule suspension,New Maixian Powder low,medium and high dose groups were given 1. 5,3,and 6 g/( kg·d) of New Maixian Powder suspension,respectively,and other groups were given an equal volume of physiological saline,continuous intragastric administration for 14 d. Next,the disease activity index( DAI) of UC rats was evaluated; the expression of NF-κB in serum was measured by enzyme-linked immunosorbent assay( ELISA); the expression of PERK and e IF-2α protein and m RNA in colon tissue was detected by Western blot and real-time quantitative polymerase chain reaction( RT q-PCR). [Results] Compared with the normal group,the DAI score and serum NF-κB level in the model group were significantly higher( P < 0. 05),and PERK and e IF-2α protein and m RNA levels in the colon tissue were increased( P < 0. 05); compared with the model group,the DAI score decreased and serum NF-κB level declined in the New Maixian Powder group,and the expression of PERK and e IF-2α protein and m RNA in New Maixian Powder medium dose and high dose groups declined( P < 0. 05). [Conclusions]New Maixian Powder has good therapeutic effect on UC rats,and its mechanism may be connected with the inhibition of the activation of PERK/e IF-2α/NF-κB signaling pathway.展开更多
Eukaryotic translation initiation factor 5A (eIFSA) is a protein-translation initiation factor in eukaryotic cells. Recent studies found that elFSA plays an important role in regulating the processes of cellular sen...Eukaryotic translation initiation factor 5A (eIFSA) is a protein-translation initiation factor in eukaryotic cells. Recent studies found that elFSA plays an important role in regulating the processes of cellular senescence and death, environmental stress response and immune response in animal and plant cells. In the present study, a cDNA containing the complete amino acid sequence of eIFSA was obtained for the first time by sequencing the Litopenaeus vannamei cDNA library, which contained a 474 bp long open reading frame encoding 157 amino acids, with the predicted molecular weight of about 17. 257 ku and theoretical isoelectric point of 5.06. Comparison analysis showed that the amino acid sequence of elFSA gene in L vannamei shared relatively high homology with that in other species. Real-time quantitative RT-PCR results indicated that the mRNA expression of elFSA gene in different tissues of L. vannamei exhibited no significant difference. Real-time quantitative RT-PCR analysis of L. vannamei hepatopancreas infected with WSSV, TSV and IHHNV showed that the mRNA levels of elFSA gene was re- spectively significantly increased, which was 2.2, 2.5 and 1.6 times of that in control group, indicating that eIFSA may be involved in the antiviral immune response of L. vannamei.展开更多
The Shine-Dalgarno (SD) sequence, when present, is known to promote translation initiation in a bacterial cell. However, the thermodynamic stability of the messenger RNA (mRNA) through its secondary structures has an ...The Shine-Dalgarno (SD) sequence, when present, is known to promote translation initiation in a bacterial cell. However, the thermodynamic stability of the messenger RNA (mRNA) through its secondary structures has an inhibitory effect on the efficiency of translation. This poses the question of whether bacterial mRNAs with SD have low secondary structure formation or not. About 3500 protein-coding genes in <i>Rhodobacter sphaeroides</i> were analyzed and a sliding window analysis of the last 100 nucleotides of the 5’ UTR and the first 100 nucleotides of ORFs was performed using <i>RNAfold</i>, a software for RNA secondary structure analysis. It was shown that mRNAs with SD are less stable than those without SD for genes located on the primary chromosome, but not for the plasmid encoded genes. Furthermore, mRNA stability is similar for genes within each chromosome except those encoded by the accessory chromosome (second chromosome). Results highlight the possible contribution of other factors like replicon-specific nucleotide composition (GC content), codon bias, and protein stability in determining the efficiency of translation initiation in both SD-dependent and SD-independent translation systems.展开更多
Alternative translational initiation is an important mechanism to increase the diversity of gene products. Although some of alternative translational initiation events have been reported, such information remains anec...Alternative translational initiation is an important mechanism to increase the diversity of gene products. Although some of alternative translational initiation events have been reported, such information remains anecdotal and does not allow for any generalizations. The number of the known alternative translational initiation genes is so few that we know little about its mechanism. There is a great demand to discover more alternative translational initiation genes. However, it is arduously time-consuming to discover novel alternative translational initiation genes by the experimental method. Therefore we systematically analyzed protein sequences available in public database and predicted 1237 protein clusters as potential alternative translational initiation events. We concluded that about 8%—10% of human genes have alternative translational initiation sites. The results significantly increased the number of alternative translation initiation events and indicated that alternative translation initiation is an important and general regulation mechanism in the cellular process.展开更多
Coding regions have complex interactions among multiple selective forces,which are manifested as biases in nucleotide composition.Previous studies have revealed a decreasing GC gradient from the 5′-end to 3′-end of ...Coding regions have complex interactions among multiple selective forces,which are manifested as biases in nucleotide composition.Previous studies have revealed a decreasing GC gradient from the 5′-end to 3′-end of coding regions in various organisms.We confirmed that this gradient is universal in eukaryotic genes,but the decrease only starts from the~25th codon.This trend is mostly found in nonsynonymous(ns)sites at which the GC gradient is universal across the eukaryotic genome.Increased GC contents at ns sites result in cheaper amino acids,indicating a universal selection for energy efficiency toward the N-termini of encoded proteins.Within a genome,the decreasing GC gradient is intensified from lowly to highly expressed genes(more and more protein products),further supporting this hypothesis.This reveals a conserved selective constraint for cheaper amino acids at the translation start that drives the increased GC contents at ns sites.Elevated GC contents can facilitate transcription but result in a more stable local secondary structure around the start codon and subsequently impede translation initiation.Conversely,the GC gradients at four-fold and two-fold synonymous sites vary across species.They could decrease or increase,suggesting different constraints acting at the GC contents of different codon sites in different species.This study reveals that the overall GC contents at the translation start are consequences of complex interactions among several major biological processes that shape the nucleotide sequences,especially efficient energy usage.展开更多
OCT4 is one of the key transcription factors in maintaining the pluripotency and self-renewal of embryonic stem (ES) cells.Human OCT4 can generate two isoforms OCT4A and OCT4B by alternative splicing.OCT4B1 is a rec...OCT4 is one of the key transcription factors in maintaining the pluripotency and self-renewal of embryonic stem (ES) cells.Human OCT4 can generate two isoforms OCT4A and OCT4B by alternative splicing.OCT4B1 is a recently discovered novel OCT4 spliced variant,which has been considered as a putative marker of stemness.Compared with the OCT4B mRNA,OCT4B1 mRNA is generated by retaining intron 2 as a cryptic exon which contains a TGA stop codon in it.As a result,the protein product of OCT4B1 mRNA could be truncated.Interestingly,we present here that OCT4B1 can indirectly produce the same protein products as OCT4B.We have demonstrated that OCT4B1 mRNA can be spliced into OCT4B mRNA,and encode three protein isoforms.The splicing of OCT4B1 mRNA into OCT4B mRNA can be remarkably inhibited by the mutation of the classical splicing site.Our result suggests that OCT4B mRNA may originate from OCT4B1 mRNA by alternative splicing.展开更多
TRPP2, a Ca^(2+)-permeable non-selective cation channel, has been shown to negatively regulate cell cycle, but the mechanism underlying this regulation is unknown. Tumor necrosis factor a(TNF-α) is a proinflammatory ...TRPP2, a Ca^(2+)-permeable non-selective cation channel, has been shown to negatively regulate cell cycle, but the mechanism underlying this regulation is unknown. Tumor necrosis factor a(TNF-α) is a proinflammatory cytokine extensively involved in immune system regulation, cell proliferation and cell survival. However, the effects and mechanisms for the role of TNF-αin laryngeal cancer remain unclear. Here, we demonstrated using western blot analyses and intracellular Ca^(2+) concentration measurements that TNF-α treatment suppressed both TRPP2 expression and ATP-induced Ca^(2+) release in a laryngeal cancer cell line(Hep-2). Knockdown of TRPP2 by a specific siRNA significantly decreased ATP-induced Ca^(2+) release and abolished the effect of TNF-α on the ATP-induced Ca^(2+) release. TNF-α treatment also enhanced Hep-2 cell proliferation and growth, as determined using cell counting and flow cytometry cell cycle assays. Moreover, TNF-α treatment down-regulated phosphorylated protein kinase R-like endoplasmic reticulum kinase(p-PERK) and phosphorylated eukaryotic translation initiation factor(p-eIF2α)expression levels, without affecting PERK and eIF2 a expression levels in Hep-2 cells. We concluded that suppressing TRPP2 expression and TRPP2-mediated Ca^(2+) signaling may be one mechanism underlying TNF-α-enhanced Hep-2 cell proliferation.These results offer new insights into the mechanisms of TNF-α-mediated laryngeal cancer cell proliferation, and provide evidences showing a potential role of TNF-α in the development of laryngeal cancer.展开更多
Mutations of the genes encoding aminoacyl-tRNA synthetases are highly associated with various central nervous system disorders.Recurrent mutations,including c.5A>G,p.D2G;c.1367C>T,p.S456L;c.1535G>A,p.R512Q an...Mutations of the genes encoding aminoacyl-tRNA synthetases are highly associated with various central nervous system disorders.Recurrent mutations,including c.5A>G,p.D2G;c.1367C>T,p.S456L;c.1535G>A,p.R512Q and c.1846_1847del,p.Y616Lfs*6 of RARS1 gene,which encodes two forms of human cytoplasmic arginyl-tRNA synthetase(hArgRS),are linked to Pelizaeus-Merzbacher-like disease(PMLD)with unclear pathogenesis.Among these mutations,c.5A>G is the most extensively reported mutation,leading to a p.D2G mutation in the N-terminal extension of the long-form hArgRS.Here,we showed the detrimental effects of R512Q substitution andΔC mutations on the structure and function of hArgRS,while the most frequent mutation c.5A>G,p.D2G acted in a different manner without impairing hArgRS activity.The nucleotide substitution c.5A>G reduced translation of hArgRS mRNA,and an upstream open reading frame contributed to the suppressed translation of the downstream main ORF.Taken together,our results elucidated distinct pathogenic mechanisms of various RARS1 mutations in PMLD.展开更多
Stress granules are non-membranous cytoplasmic foci induced by various stress conditions.It is a protective strategy used by cells to suppress overall translation during stress.In cancer cells,it was thought that the ...Stress granules are non-membranous cytoplasmic foci induced by various stress conditions.It is a protective strategy used by cells to suppress overall translation during stress.In cancer cells,it was thought that the formation of stress granules could protect them from apoptosis and induces resistance towards anti-cancer drugs or radiation treatment which makes the stress granules a potential target for cancer treatment.However,most of our understanding of stress granules are still in the stage of molecular and cell biology,and a transitional gap for its actual effect on clinical settings remains.In this review,we summarize the mechanism and effect of stress granules formation in cancer and try to illuminate its potential applications in cancer therapy,using breast cancer as an example.展开更多
Native promoters that can drive high and stable transgene expression are important tools for modifying plant traits.Although several such promoters have been reported in soybean(Glycine max),few of them function at mu...Native promoters that can drive high and stable transgene expression are important tools for modifying plant traits.Although several such promoters have been reported in soybean(Glycine max),few of them function at multiple growth and development stages and during nodule development.Here,we report that the promoters of 40S RIBOSOMAL PROTEIN SMALL SUBUNIT S28(RPS28)and EUKARYOTIC TRANSLATION INITIATION FACTOR 1(EIF1)are ideal for high expression of transgene.Through bioinformatic analysis,we determined that RPS28 and EIF1 were highly expressed during soybean growth and development,nodule development,and various biotic and abiotic stresses.Fusion of both RPS28 and EIF1 promoters,with or without their first intron,with the reporter geneβ-GLUCURONIDASE(uidA)in transgenic soybean,resulted in high GUS activity in seedlings,seeds,and nodules.Fluorimetric GUS assays showed that the RPS28 promoter and the EIF1 promoter yielded high expression,comparable to the soybean Ubiquitin(GmUbi)promoter.RPS28 and EIF1 promoters were also highly expressed in Arabidopsis thaliana and Nicotiana benthamiana.Our results indicate the potential of RPS28 and EIF1 promoters to facilitate future genetic engineering and breeding to improve the quality and yield of soybean,as well as in a wide variety of other plant species.展开更多
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.
文摘In eukaryotic cells, protein synthesis is a complex and multi-step process that has several mechanisms to start the translation including cap-dependent and cap-independent initiation. The translation control of eukaryotic gene expression occurs principally at the initiation step. In this context, it is critical that the eukaryotic translation initiation factor eIF4E bind to the 7-methylguanosine (m7G) cap present at the 5'- UTRs of most eukaryotic mRNAs. Combined with other initiation factors, elF4E mediates the mRNA recruitment on ribosomes to start the translation. Moreover, the eIF4E nuclear bodies are involved in the export of specific mRNAs from the nucleus to the cytoplasm. In this review, we focus on the elF4E structure and its physiological functions, and describe the role of eIF4E in cancer development and progression and the current therapeutic strategies to target eIF4E.
基金D.A.W.'s lab at Xiamen University is funded through grants 81773771 and 31770813 from the National Science Foundation of China and the 1000 Talent Program.
文摘Studies over the past three years have substantially expanded the involvements of eukaryotic initiation factor 3 (eIF3) in messenger RNA (mRNA) translation. It now appears that this multi-subunit complex is involved in every possible form of mRNA translation, controlling every step of protein synthesis from initiation to elongation, termination, and quality control in positive as well as negative fashion. Through the study of eIF3, we are beginning to appreciate protein synthesis as a highly integrated process coordinating protein production with protein folding, subcellular targeting, and degradation. At the same time, eIF3 subunits appear to have specific functions that probably vary between different tissues and individual cells. Considering the broad functions of eIF3 in protein homeostasis, it comes as little surprise that eIF3 is increasingly implicated in major human diseases and first attempts at therapeutically targeting eIF3 have been undertaken. Much remains to be learned, however, about subunit- and tissue-specific functions of eIF3 in protein synthesis and disease and their regulation by environmental conditions and post-translational modifications.
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generously supported by the National Natural Science Foundation of China(Nos.82072650 and 81902405)Key Research and Development Program of Zhejiang Province(No.2021C03121)+1 种基金2019 Liver Cancer Diagnosis and Treatment Communication Fund(No.CXPJJH11900009-12)Grant from Health Commission of Zhejiang Province(No.JBZX-202004).
文摘tRNA-derived small RNAs(tsRNAs)are novel non-coding RNAs that are involved in the occurrence and progression of diverse diseases.However,their exact presence and function in hepatocellular carcinoma(HCC)remain unclear.Here,differentially expressed tsRNAs in HCC were profiled.A novel tsRNA,tRNAGln-TTG derived 5′-tiRNA-Gln,is significantly downregulated,and its expression level is correlated with progression in patients.In HCC cells,5′-tiRNA-Gln overexpression impaired the proliferation,migration,and invasion in vitro and in vivo,while 5′-tiRNA-Gln knockdown yielded opposite results.5′-tiRNA-Gln exerted its function by binding eukaryotic initiation factor 4A-I(EIF4A1),which unwinds complex RNA secondary structures during translation initiation,causing the partial inhibition of translation.The suppressed downregulated proteins include ARAF,MEK1/2 and STAT3,causing the impaired signaling pathway related to HCC progression.Furthermore,based on the construction of a mutant 5′-tiRNA-Gln,the sequence of forming intramolecular G-quadruplex structure is crucial for 5′-tiRNA-Gln to strongly bind EIF4A1 and repress translation.Clinically,5′-tiRNA-Gln expression level is negatively correlated with ARAF,MEK1/2,and STAT3 in HCC tissues.Collectively,these findings reveal that 5′-tiRNA-Gln interacts with EIF4A1 to reduce related mRNA binding through the intramolecular Gquadruplex structure,and this process partially inhibits translation and HCC progression.
基金National Natural Science Foundation of China,Nos.82070967,81770930the Natural Science Foundation of Hunan Province,No.2020jj4788 (all to BJ)。
文摘Ras homolog enriched in brain(Rheb) is a small GTPase that activates mammalian target of rapamycin complex 1(mTORC1).Previous studies have shown that constitutively active Rheb can enhance the regeneration of sensory axons after spinal cord injury by activating downstream effectors of mTOR.S6K1 and4E-BP1 are important downstream effectors of mTORC1.In this study,we investigated the role of Rheb/mTOR and its downstream effectors S6K1 and 4E-BP1in the protection of retinal ganglion cells.We transfected an optic nerve crush mouse model with adeno-associated viral 2-mediated constitutively active Rheb and observed the effects on retinal ganglion cell survival and axon regeneration.We found that overexpression of constitutively active Rheb promoted survival of retinal ganglion cells in the acute(14 days) and chronic(21 and 42 days) stages of injury.We also found that either co-expression of the dominant-negative S6K1mutant or the constitutively active 4E-BP1 mutant together with constitutively active Rheb markedly inhibited axon regeneration of retinal ganglion cells.This suggests that mTORC1-mediated S6K1 activation and 4E-BP1 inhibition were necessary components for constitutively active Rheb-induced axon regeneration.However,only S6K1 activation,but not 4E-BP1 knockdown,induced axon regeneration when applied alone.Furthermore,S6K1 activation promoted the survival of retinal ganglion cells at 14 days post-injury,whereas 4E-BP1 knockdown unexpectedly slightly decreased the survival of retinal ganglion cells at 14 days postinjury.Ove rexpression of constitutively active 4E-BP1 increased the survival of retinal ganglion cells at 14 days post-injury.Likewise,co-expressing constitutively active Rheb and constitutively active 4E-BP1 markedly increased the survival of retinal ganglion cells compared with overexpression of constitutively active Rheb alone at 14 days post-injury.These findings indicate that functional 4E-BP1 and S6K1 are neuroprotective and that 4E-BP1 may exert protective effects through a pathway at least partially independent of Rhe b/mTOR.Together,our results show that constitutively active Rheb promotes the survival of retinal ganglion cells and axon regeneration through modulating S6K1 and 4E-BP1 activity.Phosphorylated S6K1 and 4E-BP1 promote axon regeneration but play an antagonistic role in the survival of retinal ganglion cells.
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.
基金This work was supported by grants from the National Natural Science Foundation of China(No.81974396,No.81874091,No.82072840,and No.82102734)the Natural Science Foundation of Hubei Province(No.2020CFB829)the Health Commission of Hubei Province Scientific Research Project(No.WJ2021F081).
文摘Objective Cisplatin(CDDP)-based chemotherapy is a first-line,drug regimen for muscle-invasive bladder cancer(BC)and metastatic bladder cancer.Clinically,resistance to CDDP restricts the clinical benefit of some bladder cancer patients.AT-rich interaction domain 1A(ARID1A)gene mutation occurs frequently in bladder cancer;however,the role of CDDP sensitivity in BC has not been studied.Methods We established ARID1A knockout BC cell lines using CRISPR/Cas9 technology.IC50 determination,flow cytometry analysis of apoptosis,and tumor xenograft assays were performed to verify changes in the CDDP sensitivity of BC cells losing ARID1A.qRT-PCR,Western blotting,RNA interference,bioinformatic analysis,and ChIP-qPCR analysis were performed to further explore the potential mechanism of ARID1A inactivation in CDDP sensitivity in BC.Results It was found that ARID1A inactivation was associated with CDDP resistance in BC cells.Mechanically,loss of ARID1A promoted the expression of eukaryotic translation initiation factor 4A3(EIF4A3)through epigenetic regulation.Increased expression of EIF4A3 promoted the expression of hsa_circ_0008399(circ0008399),a novel circular RNA(circRNA)identified in our previous study,which,to some extent,showed that ARID1A deletion caused CDDP resistance through the inhibitory effect of circ0008399 on the apoptosis of BC cells.Importantly,EIF4A3-IN-2 specifically inhibited the activity of EIF4A3 to reduce circ0008399 production and restored the sensitivity of ARID1A inactivated BC cells to CDDP.Conclusion Our research deepens the understanding of the mechanisms of CDDP resistance in BC and elucidates a potential strategy to improve the efficacy of CDDP in BC patients with ARID1A deletion through combination therapy targeting EIF4A3.
文摘BACKGROUND Breast cancer(BC) remains a public health problem. Tamoxifen(TAM) resistance has caused great difficulties for treatment of BC patients. Eukaryotic translation initiation factor 4E binding protein 1(EIF4EBP1) plays critical roles in the tumorigenesis and progression of BC. However, the expression and mechanism of EIF4EBP1 in determining the efficacy of TAM therapy in BC patients are still unclear.AIM To investigate the expression and functions of EIF4EBP1 in determining the efficacy of TAM therapy in BC patients.METHODS High-throughput sequencing data of breast tumors were downloaded from the Gene Expression Omnibus database. Differential gene expression analysis identified EIF4EBP1 to be significantly upregulated in cancer tissues. Its prognostic value was analyzed. The biological function and related pathways of EIF4EBP1 was analyzed. Subsequently, the expression of EIF4EBP1 was determined by real-time reverse transcription polymerase chain reaction and western blotting. Cell Counting Kit-8 assays, colony formation assay and wound healing assay were used to understand the phenotypes of function of EIF4EBP1.RESULTS EIF4EBP1 was upregulated in the TAM-resistant cells, and EIF4EBP1 was related to the prognosis of BC patients. Gene Set Enrichment Analysis showed that EIF4EBP1 might be involved in Hedgehog signaling pathways. Decreasing the expression of EIF4EBP1 could reverse TAM resistance, whereas overexpression of EIF4EBP1 promoted TAM resistance.CONCLUSION This study indicated that EIF4EBP1 was overexpressed in the BC and TAM-resistant cell line, which increased cell proliferation, invasion, migration and TAM resistance in BC cells.
基金Supported by Science and Technology Program of Zhejiang Province(2016C33085)
文摘[Objectives] To study the therapeutic effect and mechanism of New Maixian Powder on ulcerative colitis( UC) rats through observing its regulatory effect on the protein kinase R-like endoplasmic reticulum kinase( PERK)/eukaryotic translation initiation factor-2α( e IF-2α)/nuclear transcription factor-kappa B( NF-κB) signaling pathway. [Methods]First,60 SD rats were randomly divided into normal group,model group,mesalazine group,and New Maixian Powder low,medium and high dose groups,10 rats each group. Then,dextran sulfate sodium( DSS) was used to induce UC rats. The mesalazine group was given 0. 42 g/( kg·d) of mesalazine sustained-release granule suspension,New Maixian Powder low,medium and high dose groups were given 1. 5,3,and 6 g/( kg·d) of New Maixian Powder suspension,respectively,and other groups were given an equal volume of physiological saline,continuous intragastric administration for 14 d. Next,the disease activity index( DAI) of UC rats was evaluated; the expression of NF-κB in serum was measured by enzyme-linked immunosorbent assay( ELISA); the expression of PERK and e IF-2α protein and m RNA in colon tissue was detected by Western blot and real-time quantitative polymerase chain reaction( RT q-PCR). [Results] Compared with the normal group,the DAI score and serum NF-κB level in the model group were significantly higher( P < 0. 05),and PERK and e IF-2α protein and m RNA levels in the colon tissue were increased( P < 0. 05); compared with the model group,the DAI score decreased and serum NF-κB level declined in the New Maixian Powder group,and the expression of PERK and e IF-2α protein and m RNA in New Maixian Powder medium dose and high dose groups declined( P < 0. 05). [Conclusions]New Maixian Powder has good therapeutic effect on UC rats,and its mechanism may be connected with the inhibition of the activation of PERK/e IF-2α/NF-κB signaling pathway.
基金Supported by National Natural Science Foundation of China(31160531)
文摘Eukaryotic translation initiation factor 5A (eIFSA) is a protein-translation initiation factor in eukaryotic cells. Recent studies found that elFSA plays an important role in regulating the processes of cellular senescence and death, environmental stress response and immune response in animal and plant cells. In the present study, a cDNA containing the complete amino acid sequence of eIFSA was obtained for the first time by sequencing the Litopenaeus vannamei cDNA library, which contained a 474 bp long open reading frame encoding 157 amino acids, with the predicted molecular weight of about 17. 257 ku and theoretical isoelectric point of 5.06. Comparison analysis showed that the amino acid sequence of elFSA gene in L vannamei shared relatively high homology with that in other species. Real-time quantitative RT-PCR results indicated that the mRNA expression of elFSA gene in different tissues of L. vannamei exhibited no significant difference. Real-time quantitative RT-PCR analysis of L. vannamei hepatopancreas infected with WSSV, TSV and IHHNV showed that the mRNA levels of elFSA gene was re- spectively significantly increased, which was 2.2, 2.5 and 1.6 times of that in control group, indicating that eIFSA may be involved in the antiviral immune response of L. vannamei.
文摘The Shine-Dalgarno (SD) sequence, when present, is known to promote translation initiation in a bacterial cell. However, the thermodynamic stability of the messenger RNA (mRNA) through its secondary structures has an inhibitory effect on the efficiency of translation. This poses the question of whether bacterial mRNAs with SD have low secondary structure formation or not. About 3500 protein-coding genes in <i>Rhodobacter sphaeroides</i> were analyzed and a sliding window analysis of the last 100 nucleotides of the 5’ UTR and the first 100 nucleotides of ORFs was performed using <i>RNAfold</i>, a software for RNA secondary structure analysis. It was shown that mRNAs with SD are less stable than those without SD for genes located on the primary chromosome, but not for the plasmid encoded genes. Furthermore, mRNA stability is similar for genes within each chromosome except those encoded by the accessory chromosome (second chromosome). Results highlight the possible contribution of other factors like replicon-specific nucleotide composition (GC content), codon bias, and protein stability in determining the efficiency of translation initiation in both SD-dependent and SD-independent translation systems.
基金the National Natural Science Foundation of China (Grant Nos. 60234020 and 60572086) Tsinghua Basic Research Foundation
文摘Alternative translational initiation is an important mechanism to increase the diversity of gene products. Although some of alternative translational initiation events have been reported, such information remains anecdotal and does not allow for any generalizations. The number of the known alternative translational initiation genes is so few that we know little about its mechanism. There is a great demand to discover more alternative translational initiation genes. However, it is arduously time-consuming to discover novel alternative translational initiation genes by the experimental method. Therefore we systematically analyzed protein sequences available in public database and predicted 1237 protein clusters as potential alternative translational initiation events. We concluded that about 8%—10% of human genes have alternative translational initiation sites. The results significantly increased the number of alternative translation initiation events and indicated that alternative translation initiation is an important and general regulation mechanism in the cellular process.
基金supported by the National Key R&D Program of China(Grant No.2018YFC0910500).
文摘Coding regions have complex interactions among multiple selective forces,which are manifested as biases in nucleotide composition.Previous studies have revealed a decreasing GC gradient from the 5′-end to 3′-end of coding regions in various organisms.We confirmed that this gradient is universal in eukaryotic genes,but the decrease only starts from the~25th codon.This trend is mostly found in nonsynonymous(ns)sites at which the GC gradient is universal across the eukaryotic genome.Increased GC contents at ns sites result in cheaper amino acids,indicating a universal selection for energy efficiency toward the N-termini of encoded proteins.Within a genome,the decreasing GC gradient is intensified from lowly to highly expressed genes(more and more protein products),further supporting this hypothesis.This reveals a conserved selective constraint for cheaper amino acids at the translation start that drives the increased GC contents at ns sites.Elevated GC contents can facilitate transcription but result in a more stable local secondary structure around the start codon and subsequently impede translation initiation.Conversely,the GC gradients at four-fold and two-fold synonymous sites vary across species.They could decrease or increase,suggesting different constraints acting at the GC contents of different codon sites in different species.This study reveals that the overall GC contents at the translation start are consequences of complex interactions among several major biological processes that shape the nucleotide sequences,especially efficient energy usage.
基金supported by the National Basic Research Program of China (973 Program) (No 2006CB943601)the National Natural Science Foundation of China (NSFC) (No 90919042)
文摘OCT4 is one of the key transcription factors in maintaining the pluripotency and self-renewal of embryonic stem (ES) cells.Human OCT4 can generate two isoforms OCT4A and OCT4B by alternative splicing.OCT4B1 is a recently discovered novel OCT4 spliced variant,which has been considered as a putative marker of stemness.Compared with the OCT4B mRNA,OCT4B1 mRNA is generated by retaining intron 2 as a cryptic exon which contains a TGA stop codon in it.As a result,the protein product of OCT4B1 mRNA could be truncated.Interestingly,we present here that OCT4B1 can indirectly produce the same protein products as OCT4B.We have demonstrated that OCT4B1 mRNA can be spliced into OCT4B mRNA,and encode three protein isoforms.The splicing of OCT4B1 mRNA into OCT4B mRNA can be remarkably inhibited by the mutation of the classical splicing site.Our result suggests that OCT4B mRNA may originate from OCT4B1 mRNA by alternative splicing.
基金supported by the Anhui Provincial Natural Science Foundation (1408085MH157)Supporting Program for Excellent Young Talents in Universities of Anhui Province, Outstanding Young Investigator of Anhui Medical University, National Natural Science Foundation of China (81570403, 81371284)Scientific Research Grant ofAnhui Medical University (2015xk1080)
文摘TRPP2, a Ca^(2+)-permeable non-selective cation channel, has been shown to negatively regulate cell cycle, but the mechanism underlying this regulation is unknown. Tumor necrosis factor a(TNF-α) is a proinflammatory cytokine extensively involved in immune system regulation, cell proliferation and cell survival. However, the effects and mechanisms for the role of TNF-αin laryngeal cancer remain unclear. Here, we demonstrated using western blot analyses and intracellular Ca^(2+) concentration measurements that TNF-α treatment suppressed both TRPP2 expression and ATP-induced Ca^(2+) release in a laryngeal cancer cell line(Hep-2). Knockdown of TRPP2 by a specific siRNA significantly decreased ATP-induced Ca^(2+) release and abolished the effect of TNF-α on the ATP-induced Ca^(2+) release. TNF-α treatment also enhanced Hep-2 cell proliferation and growth, as determined using cell counting and flow cytometry cell cycle assays. Moreover, TNF-α treatment down-regulated phosphorylated protein kinase R-like endoplasmic reticulum kinase(p-PERK) and phosphorylated eukaryotic translation initiation factor(p-eIF2α)expression levels, without affecting PERK and eIF2 a expression levels in Hep-2 cells. We concluded that suppressing TRPP2 expression and TRPP2-mediated Ca^(2+) signaling may be one mechanism underlying TNF-α-enhanced Hep-2 cell proliferation.These results offer new insights into the mechanisms of TNF-α-mediated laryngeal cancer cell proliferation, and provide evidences showing a potential role of TNF-α in the development of laryngeal cancer.
基金supported by the National Key Research and Development Program of China(2017YFA0504000)the Natural Science Foundation of China(91940302,31500644,31570792,31822015,81870896,31670801,31870811)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB19010203)Key Laboratory of Reproductive Genetics(Zhejiang University),Ministry of Education,P.R.China(ZDFY2020-RG-0003)Shanghai Key Laboratory of Embryo Original Diseases(Shelab201904).
文摘Mutations of the genes encoding aminoacyl-tRNA synthetases are highly associated with various central nervous system disorders.Recurrent mutations,including c.5A>G,p.D2G;c.1367C>T,p.S456L;c.1535G>A,p.R512Q and c.1846_1847del,p.Y616Lfs*6 of RARS1 gene,which encodes two forms of human cytoplasmic arginyl-tRNA synthetase(hArgRS),are linked to Pelizaeus-Merzbacher-like disease(PMLD)with unclear pathogenesis.Among these mutations,c.5A>G is the most extensively reported mutation,leading to a p.D2G mutation in the N-terminal extension of the long-form hArgRS.Here,we showed the detrimental effects of R512Q substitution andΔC mutations on the structure and function of hArgRS,while the most frequent mutation c.5A>G,p.D2G acted in a different manner without impairing hArgRS activity.The nucleotide substitution c.5A>G reduced translation of hArgRS mRNA,and an upstream open reading frame contributed to the suppressed translation of the downstream main ORF.Taken together,our results elucidated distinct pathogenic mechanisms of various RARS1 mutations in PMLD.
基金This work was supported by the National Natural Science Foundation of China(No.82002979 and 81702839)the Scientific Research and Development Funds of Peking Uni・versity People's Hospital,China(No.RDY2020-16).
文摘Stress granules are non-membranous cytoplasmic foci induced by various stress conditions.It is a protective strategy used by cells to suppress overall translation during stress.In cancer cells,it was thought that the formation of stress granules could protect them from apoptosis and induces resistance towards anti-cancer drugs or radiation treatment which makes the stress granules a potential target for cancer treatment.However,most of our understanding of stress granules are still in the stage of molecular and cell biology,and a transitional gap for its actual effect on clinical settings remains.In this review,we summarize the mechanism and effect of stress granules formation in cancer and try to illuminate its potential applications in cancer therapy,using breast cancer as an example.
基金supported by National Natural Science Foundationof China(Grant No.31870257 and U21A20181 to X.W,Grant no.32170728 to H.W.)the National Key Research,and Development,Program(Grant No.2018YFE0112100 to X.W.)+1 种基金Excellent Youth Foundation of Henan Province(Grant No.222300420025 to H.W.)the 111 Project of China(Grant No.D16014).
文摘Native promoters that can drive high and stable transgene expression are important tools for modifying plant traits.Although several such promoters have been reported in soybean(Glycine max),few of them function at multiple growth and development stages and during nodule development.Here,we report that the promoters of 40S RIBOSOMAL PROTEIN SMALL SUBUNIT S28(RPS28)and EUKARYOTIC TRANSLATION INITIATION FACTOR 1(EIF1)are ideal for high expression of transgene.Through bioinformatic analysis,we determined that RPS28 and EIF1 were highly expressed during soybean growth and development,nodule development,and various biotic and abiotic stresses.Fusion of both RPS28 and EIF1 promoters,with or without their first intron,with the reporter geneβ-GLUCURONIDASE(uidA)in transgenic soybean,resulted in high GUS activity in seedlings,seeds,and nodules.Fluorimetric GUS assays showed that the RPS28 promoter and the EIF1 promoter yielded high expression,comparable to the soybean Ubiquitin(GmUbi)promoter.RPS28 and EIF1 promoters were also highly expressed in Arabidopsis thaliana and Nicotiana benthamiana.Our results indicate the potential of RPS28 and EIF1 promoters to facilitate future genetic engineering and breeding to improve the quality and yield of soybean,as well as in a wide variety of other plant species.