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1.
Phys Chem Chem Phys ; 26(14): 10660-10672, 2024 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-38511550

RESUMO

The cap-dependent mRNA translation is dysregulated in many kinds of cancers. The interaction between eIF4E and eIF4G through a canonical eIF4E-binding motif (CEBM) determines the efficacy of the cap-dependent mRNA translation. eIF4E-binding proteins (4E-BPs) share the CEBM and compete with eIF4G for the same binding surface of eIF4E and then inhibit the mRNA translation. 4E-BPs function as tumor repressors in nature. Hyperphosphorylation of 4E-BPs regulates the structure folding and causes the dissociation of 4E-BPs from eIF4E. However, until now, there has been no structure of the full-length 4E-BPs in complex with eIF4E. The regulation mechanism of phosphorylation is still unclear. In this work, we first investigate the interactions of human eIF4E with the CEBM and an auxiliary eIF4E-binding motif (AEBM) in eIF4G and 4E-BPs. The results unravel that the structure and interactions of the CEBM are highly conserved between eIF4G and 4E-BPs. However, the extended CEBM (ECEBM) in 4E-BPs forms a longer helix than that in eIF4G. The residue R62 in the ECEBM of 4E-BP2 forms salt bridges with E32 and E70 of eIF4E. The residue R63 of 4E-BP2 forms two special hydrogen bonds with N77 of eIF4E. Both of these interactions are missing in eIF4G. The AEBM of 4E-BPs folds into a ß-sheet conformation, which protects V81 inside a hydrophobic core in 4E-BP2. In eIF4G, the AEBM exists in a random coil state. The hydrophilic residues S637 and D638 of eIF4G open the hydrophobic core for solvents. The results show that the ECEBM and AEBM may be responsible for the competing advantage of 4E-BP2. Finally, based on our previous work (J. Zeng, F. Jiang and Y. D. Wu, J. Chem. Theory Comput., 2017, 13, 320), the human eIF4E:4E-BP2 complex (eIF4E:BP2P18-I88) including all reported phosphorylation sites is predicted. The eIF4E:BP2P18-I88 complex is different from the existing experimental eIF4E:eIF4G complex and provides an important structure for further studying the regulation mechanism of phosphorylation in 4E-BPs.


Assuntos
Fator de Iniciação 4E em Eucariotos , Fator de Iniciação 4G em Eucariotos , Humanos , Proteínas de Transporte/metabolismo , Fator de Iniciação 4E em Eucariotos/química , Fator de Iniciação 4E em Eucariotos/genética , Fator de Iniciação 4E em Eucariotos/metabolismo , Fator de Iniciação 4G em Eucariotos/química , Fator de Iniciação 4G em Eucariotos/genética , Fator de Iniciação 4G em Eucariotos/metabolismo , Ligação Proteica , Biossíntese de Proteínas
2.
Front Endocrinol (Lausanne) ; 15: 1360043, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38516410

RESUMO

Background: The mechanistic target of rapamycin (mTOR) signaling pathway has a significant effect on central precocious puberty (CPP). However, the causality between mTOR-dependent circulating protein levels and CPP is still unclear. Our aim is to assess the effects of seven mTOR-dependent circulating protein levels on CPP using Mendelian randomization (MR). Methods: Instrumental variables (IVs) for mTOR-dependent circulating protein levels were retrieved from the proteomics-GWAS INTERVAL study and eQTLGen. The summary-level genetic datasets for CPP outcome were obtained from the FinnGen Consortium. Inverse-variance weighted (IVW) was used as the primary method and the pleiotropy, heterogeneity and robustness of the analyses were detected as sensitivity analysis. Positive exposures in the discovery cohort would be revalidated in the validation cohort. Results: This two-sample MR study revealed a causal association between eIF4G level in plasma and CPP in both discovery cohort (IVW: OR = 0.45, 95% CI = 0.22-0.91, p = 0.026) and validation cohort (IVW: OR = 0.45, 95% CI = 0.24-0.85, p = 0.014). Conclusions: There was a causal association between eIF4G level in plasma and CPP. Whether eIF4G can be used for the prevention or treatment of CPP needs to be explored in further studies.


Assuntos
Puberdade Precoce , Serina-Treonina Quinases TOR , Humanos , Serina-Treonina Quinases TOR/genética , Fator de Iniciação 4G em Eucariotos , Análise da Randomização Mendeliana , Puberdade Precoce/genética , Causalidade
3.
Oncogene ; 43(15): 1098-1112, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38388710

RESUMO

The non-canonical translation initiation factor EIF4G2 plays essential roles in cellular stress responses via translation of selective mRNA cohorts. Currently there is limited and conflicting information regarding its involvement in cancer development and progression. Here we assessed its role in endometrial cancer (EC), in a cohort of 280 EC patients across different types, grades, and stages, and found that low EIF4G2 expression highly correlated with poor overall- and recurrence-free survival in Grade 2 EC patients, monitored over a period of up to 12 years. To establish a causative connection between low EIF4G2 expression and cancer progression, we stably knocked-down EIF4G2 in two human EC cell lines in parallel. EIF4G2 depletion resulted in increased resistance to conventional therapies and increased the prevalence of molecular markers for aggressive cell subsets, altering their transcriptional and proteomic landscapes. Prominent among the proteins with decreased abundance were Kinesin-1 motor proteins, KIF5B and KLC1, 2, 3. Multiplexed imaging of the EC patient tumor cohort showed a correlation between decreased expression of the kinesin proteins, and poor survival in patients with tumors of certain grades and stages. These findings reveal potential novel biomarkers for Grade 2 EC with ramifications for patient stratification and therapeutic interventions.


Assuntos
Neoplasias do Endométrio , Cinesinas , Feminino , Humanos , Cinesinas/genética , Proteômica , Linhagem Celular , Neoplasias do Endométrio/genética , Neoplasias do Endométrio/patologia , Fator de Iniciação 4G em Eucariotos/genética , Fator de Iniciação 4G em Eucariotos/metabolismo
4.
J Orthop Surg Res ; 19(1): 134, 2024 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-38342889

RESUMO

Stimulating bone formation potentially suggests therapeutics for orthopedic diseases including osteoporosis and osteoarthritis. Osteoblasts are key to bone remodeling because they act as the only bone-forming cells. miR-877-5p has a chondrocyte-improving function in osteoarthritis, but its effect on osteoblast differentiation is unknown. Here, miR-877-5p-mediated osteoblast differentiation was studied. Real-time reverse transcriptase-polymerase chain reaction was performed to measure miR-877-5p expression during the osteogenic differentiation of MC3T3-E1 cells. Osteoblast markers, including alkaline phosphatase (ALP), collagen type I a1 chain, and osteopontin, were measured and detected by alizarin red staining and ALP staining. Potential targets of miR-877-5p were predicted from three different algorithms: starBase ( http://starbase.sysu.edu.cn/ ), PITA ( http://genie.weizmann.ac.il/pubs/mir07/mir07_data.html ), and miRanda ( http://www.microrna.org/microrna/home.do ). It was further verified by dual luciferase reporter gene assay. The experimental results found that miR-877-5p was upregulated during the osteogenic differentiation of MC3T3-E1 cells. Overexpression of miR-877-5p promoted osteogenic differentiation, which was characterized by increased cell mineralization, ALP activity, and osteogenesis-related gene expression. Knockdown of miR-877-5p produced the opposite result. Dual luciferase reporter gene assay showed that miR-877-5p directly targeted eukaryotic translation initiation factor 4γ2 (EIF4G2). Overexpression of EIF4G2 inhibited osteogenic differentiation and reversed the promoting effect of overexpression of miR-135-5p on osteogenic differentiation. These results indicate that miR-877-5p might have a therapeutic application related to its promotion of bone formation through targeting EIF4G2.


Assuntos
MicroRNAs , Osteoartrite , Humanos , Osteogênese/genética , MicroRNAs/genética , MicroRNAs/metabolismo , Diferenciação Celular/genética , Osteoblastos/metabolismo , Luciferases/metabolismo , Osteoartrite/metabolismo , Células Cultivadas , Fator de Iniciação 4G em Eucariotos/metabolismo
6.
Sci Rep ; 14(1): 251, 2024 01 02.
Artigo em Inglês | MEDLINE | ID: mdl-38167853

RESUMO

Programmable protein scaffolds are invaluable in the development of genome engineering tools. The pentatricopeptide repeat (PPR) protein is an attractive platform for RNA manipulation because of its programmable RNA-binding selectivity, which is determined by the combination of amino acid species at three specific sites in the PPR motif. Translation is a key RNA regulatory step that determines the final gene expression level and is involved in various human diseases. In this study, designer PPR protein was used to develop a translational enhancement technique by fusion with the translation initiation factor eIF4G. The results showed that the PPR-eIF4G fusion protein could activate the translation of endogenous c-Myc and p53 mRNAs and control cell fate, indicating that PPR-based translational enhancement is a versatile technique applicable to various endogenous mRNAs in mammalian cells. In addition, the translational enhancement was dependent on both the target position and presence of eIF4G, suggesting the presence of an unknown translation activation mechanism.


Assuntos
Fator de Iniciação 4G em Eucariotos , Proteínas de Ligação a RNA , Animais , Humanos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Fator de Iniciação 4G em Eucariotos/genética , Fator de Iniciação 4G em Eucariotos/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , RNA , Mamíferos/genética , Mamíferos/metabolismo
7.
Sci Rep ; 14(1): 2178, 2024 01 25.
Artigo em Inglês | MEDLINE | ID: mdl-38272944

RESUMO

Recognition of the mRNA 5' end is a critical step needed for translation initiation. This step is performed by the cap binding protein eIF4E, which joins the larger eIF4G subunit to form the eIF4F complex. Trypanosomatids have a minimum of five different eIF4F-like complexes formed through specific but not well-defined interactions between four different eIF4E and five eIF4G homologues. The EIF4E6/EIF4G5 complex has been linked with the stage-specific translation of mRNAs encoding the major Trypanosoma brucei virulence factors. Here, to better define the molecular basis for the TbEIF4E6/TbEIF4G5 interaction, we describe the identification of the peptide interacting with TbEIF4E6 in the region comprising residues 79-166 of TbEIF4G5. The TbEIF4E6-TbEIF4G5_79-116 complex reconstituted with recombinant proteins is highly stable even in the absence of cap-4. The crystal structure of the complex was subsequently solved, revealing extensive interacting surfaces. Comparative analyses highlight the conservation of the overall structural arrangement of different eIF4E/eIF4G complexes. However, highly different interacting surfaces are formed with distinct binding contacts occurring both in the canonical and noncanonical elements within eIF4G and the respective eIF4E counterpart. These specific pairs of complementary interacting surfaces are likely responsible for the selective association needed for the formation of distinct eIF4F complexes in trypanosomatids.


Assuntos
Fator de Iniciação 4F em Eucariotos , Trypanosoma brucei brucei , Fator de Iniciação 4F em Eucariotos/metabolismo , Fator de Iniciação 4G em Eucariotos/metabolismo , Fator de Iniciação 4E em Eucariotos/metabolismo , Trypanosoma brucei brucei/genética , Ligação Proteica , RNA Mensageiro/metabolismo
8.
Thorac Cancer ; 15(1): 44-56, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37993106

RESUMO

BACKGROUND: Circular RNAs (circRNAs) have been reported to be involved in the initiation and development of cancers. The aim of this study was to determine the role of a circRNA, circ_0020123, in the development of non-small cell lung cancer (NSCLC). METHODS: The expression of circ_0020123, microRNA-146a-5p (miR-146a-5p), and eukaryotic translation initiation factor 4 gamma 2 (EIF4G2) mRNA was detected by quantitative real-time PCR (qPCR). Western blot was used to determine the protein levels of cyclin D1, Bax, MMP-9, and EIF4G2. Cell proliferation was assessed by cell counting kit-8 (CCK-8) assay and colony formation assay. Flow cytometry assay was applied to determine cell cycle apoptosis. Cell migration and invasion were assessed using transwell assay. The potential relationship between miR-146a-5p and circ_0020123 or EIF4G2 was ascertained by dual-luciferase reporter assay and RIP assay. The role of circ_0020123 in vivo was explored by xenograft assay. RESULTS: Circ_0020123 was upregulated in NSCLC, and circ_0020123 knockdown repressed proliferation, migration, and invasion of NSCLC cells. Circ_0020123 targeted miR-146a-5p, and miR-146a-5p inhibitor reversed the effects of circ_0020123 knockdown on NSCLC cells. In addition, miR-146a-5p suppressed cell proliferation, migration, and invasion by targeting EIF4G2. Moreover, the antitumor role of circ_0020123 knockdown was verified in vivo. CONCLUSION: Knockdown of circ_0020123 inhibited NSCLC cell progression and tumor growth by targeting the miR-146a-5p/EIF4G2 axis.


Assuntos
Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , MicroRNAs , Humanos , Carcinoma Pulmonar de Células não Pequenas/genética , Neoplasias Pulmonares/genética , Apoptose , Contagem de Células , Proliferação de Células , MicroRNAs/genética , Fator de Iniciação 4G em Eucariotos/genética
9.
Nat Cancer ; 5(1): 30-46, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37845485

RESUMO

In vitro-transcribed (IVT) mRNA has arisen as a rapid method for the production of nucleic acid drugs. Here, we have constructed an oncolytic IVT mRNA that utilizes human rhinovirus type 2 (HRV2) internal ribosomal entry sites (IRESs) to selectively trigger translation in cancer cells with high expression of EIF4G2 and PTBP1. The oncolytic effect was provided by a long hGSDMDc .825 T>A/c.884 A>G-F1LCT mutant mRNA sequence with mitochondrial inner membrane cardiolipin targeting toxicity that triggers mitophagy. Utilizing the permuted intron-exon (PIE) splicing circularization strategy and lipid nanoparticle (LNP) encapsulation reduced immunogenicity of the mRNA and enabled delivery to eukaryotic cells in vivo. Engineered HRV2 IRESs-GSDMDp.D275E/E295G-F1LCT circRNA-LNPs (GSDMDENG circRNA) successfully inhibited EIF4G2+/PTBP1+ pan-adenocarcinoma xenografts growth. Importantly, in a spontaneous tumor model with abnormal EIF4G2 and PTBP1 caused by KRAS G12D mutation, GSDMDENG circRNA significantly prevented the occurrence of pancreatic, lung and colon adenocarcinoma, improved the survival rate and induced persistent KRAS G12D tumor antigen-specific cytotoxic T lymphocyte responses.


Assuntos
Adenocarcinoma , Neoplasias do Colo , Humanos , RNA Circular , Cardiolipinas , Proteínas Proto-Oncogênicas p21(ras) , RNA Mensageiro/genética , Fator de Iniciação 4G em Eucariotos/genética , Fator de Iniciação 4G em Eucariotos/metabolismo , Ribonucleoproteínas Nucleares Heterogêneas/genética , Proteína de Ligação a Regiões Ricas em Polipirimidinas/genética , Proteína de Ligação a Regiões Ricas em Polipirimidinas/metabolismo
10.
Phys Chem Chem Phys ; 26(3): 2073-2081, 2024 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-38131207

RESUMO

Interaction between the cap-binding protein eIF4E and the scaffolding protein eIF4G is essential for the cap-dependent translation initiation in eukaryotes. In the Saccharomyces cerevisiae eIF4G/eIF4E complex, the intrinsically disordered eIF4E-binding domain of eIF4G folds into a bracelet-like structure upon binding to eIF4E. Aiming to unveil the molecular mechanism underlying the binding-wrapping process of eIF4G with eIF4E, we performed extensive coarse-grained molecular dynamics simulations and transition path analysis in this work. The major transition pathway revealed from our simulations showed that docking of the eIF4E-binding motif of eIF4G to the folded core of eIF4E initiates the binding process and then the disordered eIF4G wraps around the N-terminal tail of eIF4E. Additionally, we identified a minor transition pathway which indicates the involvement of topological frustration in the binding process. By manipulating the interaction strength of the wrapping contacts and the latching contacts, we further dissected factors affecting the formation of topological frustration and the binding transition kinetics. Our findings provide new clues for experimental studies on the binding mechanism of eIF4G to eIF4E in the future and exemplify the involvement of topological frustration in the binding process of intrinsically disordered proteins.


Assuntos
Fator de Iniciação 4E em Eucariotos , Fator de Iniciação 4G em Eucariotos , Fator de Iniciação 4E em Eucariotos/química , Fator de Iniciação 4E em Eucariotos/genética , Fator de Iniciação 4E em Eucariotos/metabolismo , Fator de Iniciação 4G em Eucariotos/química , Fator de Iniciação 4G em Eucariotos/genética , Fator de Iniciação 4G em Eucariotos/metabolismo , Simulação de Dinâmica Molecular , Biossíntese de Proteínas , Saccharomyces cerevisiae , Ligação Proteica
11.
Life Sci Alliance ; 7(3)2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38129098

RESUMO

Tumor cells often exploit the protein translation machinery, resulting in enhanced protein expression essential for tumor growth. Since canonical translation initiation is often suppressed because of cell stress in the tumor microenvironment, non-canonical translation initiation mechanisms become particularly important for shaping the tumor proteome. EIF4G2 is a non-canonical translation initiation factor that mediates internal ribosome entry site (IRES)- and uORF-dependent initiation mechanisms, which can be used to modulate protein expression in cancer. Here, we explored the contribution of EIF4G2 to cancer by screening the COSMIC database for EIF4G2 somatic mutations in cancer patients. Functional examination of missense mutations revealed deleterious effects on EIF4G2 protein-protein interactions and, importantly, on its ability to mediate non-canonical translation initiation. Specifically, one mutation, R178Q, led to reductions in protein expression and near-complete loss of function. Two other mutations within the MIF4G domain specifically affected EIF4G2's ability to mediate IRES-dependent translation initiation but not that of target mRNAs with uORFs. These results shed light on both the structure-function of EIF4G2 and its potential tumor suppressor effects.


Assuntos
Neoplasias , Biossíntese de Proteínas , Humanos , Biossíntese de Proteínas/genética , Mutação/genética , Neoplasias/genética , Fator de Iniciação 4G em Eucariotos/genética , Microambiente Tumoral
12.
PLoS Pathog ; 19(11): e1011417, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37983287

RESUMO

Successful subversion of translation initiation factors eIF4E determines the infection success of potyviruses, the largest group of viruses affecting plants. In the natural variability of many plant species, resistance to potyvirus infection is provided by polymorphisms at eIF4E that renders them inadequate for virus hijacking but still functional in translation initiation. In crops where such natural resistance alleles are limited, the genetic inactivation of eIF4E has been proposed for the engineering of potyvirus resistance. However, recent findings indicate that knockout eIF4E alleles may be deleterious for plant health and could jeopardize resistance efficiency in comparison to functional resistance proteins. Here, we explored the cause of these adverse effects by studying the role of the Arabidopsis eIF4E1, whose inactivation was previously reported as conferring resistance to the potyvirus clover yellow vein virus (ClYVV) while also promoting susceptibility to another potyvirus turnip mosaic virus (TuMV). We report that eIF4E1 is required to maintain global plant translation and to restrict TuMV accumulation during infection, and its absence is associated with a favoured virus multiplication over host translation. Furthermore, our findings show that, in the absence of eIF4E1, infection with TuMV results in the production of a truncated eIFiso4G1 protein. Finally, we demonstrate a role for eIFiso4G1 in TuMV accumulation and in supporting plant fitness during infection. These findings suggest that eIF4E1 counteracts the hijacking of the plant translational apparatus during TuMV infection and underscore the importance of preserving the functionality of translation initiation factors eIF4E when implementing potyvirus resistance strategies.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Potyvirus , Arabidopsis/metabolismo , Fator de Iniciação 4E em Eucariotos/genética , Fator de Iniciação 4E em Eucariotos/metabolismo , Potyvirus/fisiologia , Plantas Geneticamente Modificadas/metabolismo , Doenças das Plantas/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Fator de Iniciação 4G em Eucariotos/metabolismo
13.
EMBO J ; 42(24): e113240, 2023 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-37984430

RESUMO

Protein requirements of eukaryotic cells are ensured by proteostasis, which is mediated by tight control of TORC1 activity. Upon TORC1 inhibition, protein degradation is increased and protein synthesis is reduced through inhibition of translation initiation to maintain cell viability. Here, we show that the ribosome-associated complex (RAC)/Ssb chaperone system, composed of the HSP70 chaperone Ssb and its HSP40 co-chaperone Zuo1, is required to maintain proteostasis and cell viability under TORC1 inhibition in Saccharomyces cerevisiae. In the absence of Zuo1, translation does not decrease in response to the loss of TORC1 activity. A functional interaction between Zuo1 and Ssb is required for proper translational control and proteostasis maintenance upon TORC1 inhibition. Furthermore, we have shown that the rapid degradation of eIF4G following TORC1 inhibition is mediated by autophagy and is prevented in zuo1Δ cells, contributing to decreased survival in these conditions. We found that autophagy is defective in zuo1Δ cells, which impedes eIF4G degradation upon TORC1 inhibition. Our findings identify an essential role for RAC/Ssb in regulating translation in response to changes in TORC1 signalling.


Assuntos
Proteínas de Saccharomyces cerevisiae , Fator de Iniciação 4G em Eucariotos/genética , Fator de Iniciação 4G em Eucariotos/metabolismo , Proteínas de Choque Térmico HSP70/genética , Proteínas de Choque Térmico HSP70/metabolismo , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Ribossomos/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo
14.
J Biosci ; 482023.
Artigo em Inglês | MEDLINE | ID: mdl-38018538

RESUMO

Initiation of translation is the first of the three obligatory steps required for protein synthesis and is carried out by a large number of protein factors called initiation factors in conjunction with ribosomes. One of the key conserved protein factors in eukaryotes that plays a role in this process is eIF4A, which has three homologues in humans with eIF4A1 being the primary factor playing a role in translation initiation. eIF4As are members of the family of DEAD-box helicases that carry out different biological functions. eIF4A1s are recruited to translation initiation complexes via association with eIF4G and have ATP binding, ATP hydrolysis, RNA binding, and unwinding activities. Plasmodium and trypanosomatids such as Leishmania and Trypanosoma are parasites that cause human disease. While mechanistically the function of eIF4A1s in eukaryotes is wellunderstood, the orthologues peIF4A1s and keIF4A1s in Plasmodium and trypanosomatids are not well-studied. Here, we have used bioinformatics tools and homology modelling/structure prediction to study the motifs and functional signatures of Plasmodium and trypanosomatid peIF4A1s/keIF4A1s. We report a high degree of sequence conservation, structural conservation, and conservation of protein-protein interaction signatures of Plasmodium and trypanosomatid peIF4A1s/keIF4A1s in comparison with human eIF4A1. Thus, in spite of the great divergence in evolution between these parasites and higher eukaryotes, there is remarkable conservation of motifs and functional signatures in Plasmodium and trypanosomatid peIF4A1s/keIF4A1s.


Assuntos
Fator de Iniciação 4G em Eucariotos , Plasmodium , Humanos , Sequência de Aminoácidos , Ligação Proteica , Fator de Iniciação 4G em Eucariotos/química , Fator de Iniciação 4G em Eucariotos/genética , Fator de Iniciação 4G em Eucariotos/metabolismo , Proteínas/metabolismo , Eucariotos , Plasmodium/genética , Plasmodium/metabolismo , Trifosfato de Adenosina/metabolismo
15.
Eur J Med Chem ; 260: 115781, 2023 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-37669595

RESUMO

Overexpression of eIF4E is common in patients with various solid tumors and hematologic cancers. As a potential anti-cancer target, eIF4E has attracted extensive attention from researchers. At the same time, mTOR kinases inhibitors and MNK kinases inhibitors, which are directly related to regulation of eIF4E, have been rapidly developed. To explore the optimal anti-cancer targets among MNK, mTOR, and eIF4E, this review provides a detailed classification and description of the anti-cancer activities of promising compounds. In addition, the structures and activities of some dual-target inhibitors are briefly described. By analyzing the different characteristics of the inhibitors, it can be concluded that MNK1/2 and eIF4E/eIF4G interaction inhibitors are superior to mTOR inhibitors. Simultaneous inhibition of MNK and eIF4E/eIF4G interaction may be the most promising anti-cancer method for targeting translation initiation.


Assuntos
Neoplasias Hematológicas , Neoplasias , Humanos , Fator de Iniciação 4G em Eucariotos , Serina-Treonina Quinases TOR , Neoplasias/tratamento farmacológico , Fator de Iniciação 4E em Eucariotos
16.
Genes Dev ; 37(15-16): 760-777, 2023 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-37704377

RESUMO

The mRNA 3' poly(A) tail plays a critical role in regulating both mRNA translation and turnover. It is bound by the cytoplasmic poly(A) binding protein (PABPC), an evolutionarily conserved protein that can interact with translation factors and mRNA decay machineries to regulate gene expression. Mammalian PABPC1, the prototypical PABPC, is expressed in most tissues and interacts with eukaryotic translation initiation factor 4G (eIF4G) to stimulate translation in specific contexts. In this study, we uncovered a new mammalian PABPC, which we named neural PABP (neuPABP), as it is predominantly expressed in the brain. neuPABP maintains a unique architecture as compared with other PABPCs, containing only two RNA recognition motifs (RRMs) and maintaining a unique N-terminal domain of unknown function. neuPABP expression is activated in neurons as they mature during synaptogenesis, where neuPABP localizes to the soma and postsynaptic densities. neuPABP interacts with the noncoding RNA BC1, as well as mRNAs coding for ribosomal and mitochondrial proteins. However, in contrast to PABPC1, neuPABP does not associate with actively translating mRNAs in the brain. In keeping with this, we show that neuPABP has evolved such that it does not bind eIF4G and as a result fails to support protein synthesis in vitro. Taken together, these results indicate that mammals have expanded their PABPC repertoire in the brain and propose that neuPABP may support the translational repression of select mRNAs.


Assuntos
Fator de Iniciação 4G em Eucariotos , Proteínas de Ligação a Poli(A) , Animais , Proteínas de Ligação a Poli(A)/genética , Neurônios , Encéfalo , Mamíferos
17.
Mol Cell Biol ; 43(10): 485-499, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37724583

RESUMO

IRES mediated translation initiation requires a different repertoire of factors than canonical cap-dependent translation. Treatments that inhibit the canonical translation factor EIF4G1 have little or no effect on the ability of the Insr and Igf1r cellular IRESes to promote translation. Transcripts for two cellular receptors contain RNA elements that facilitate translation initiation without intact EIF4G1. Cellular IRES mechanisms may resemble viral type III IRESes allowing them to promote translate with a limited number of initiation factors allowing them to work under stress conditions when canonical translation is repressed.


Assuntos
Biossíntese de Proteínas , Regiões 5' não Traduzidas/genética , Ribossomos/metabolismo , Fator de Iniciação 4G em Eucariotos/genética , Fator de Iniciação 4G em Eucariotos/metabolismo , Receptor de Insulina/genética , Receptor de Insulina/metabolismo , Receptores de Somatomedina/metabolismo , RNA Viral/metabolismo
18.
Shock ; 60(4): 594-602, 2023 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-37646610

RESUMO

ABSTRACT: Gut barrier dysfunction caused by intestinal ischemia/reperfusion (I/R) injury is associated with substantial death and morbidity. In this research, the role of microRNAs (miRNAs) in regulating intestinal I/R injury was investigated. We used miRNA sequencing to analyze clinical ischemic and normal intestinal samples. Through bioinformatics analysis based on sequencing results, we found that upregulated miRNAs inhibited epithelial barrier function and cell proliferation, with miR-379-5p being the most significantly upregulated in the ischemic intestine. Further studies confirmed the role of miR-379-5p through experiments in the human ischemic intestine, the mouse I/R injury model in vivo , and cell hypoxia/reoxygenation models in vitro . Inhibiting miR-379-5p increased epithelial cell proliferation and improved barrier function after I/R injury. We also identified eukaryotic translation initiation factor 4 gamma 2 (EIF4G2) as a downstream target gene of miR-379-5p through bioinformatics prediction and experimental verification. The findings suggest that inhibiting miR-379-5p could improve intestinal epithelial cell proliferation and barrier function by targeting EIF4G2. The goal of this study was to find a potential target for treating I/R injury in the intestine, as well as to prevent and mitigate the damage caused.


Assuntos
MicroRNAs , Traumatismo por Reperfusão , Animais , Humanos , Camundongos , Apoptose , Proliferação de Células/genética , Modelos Animais de Doenças , Fator de Iniciação 4G em Eucariotos , Isquemia , MicroRNAs/genética , Recuperação de Função Fisiológica , Reperfusão , Traumatismo por Reperfusão/genética
19.
Nat Commun ; 14(1): 4977, 2023 08 28.
Artigo em Inglês | MEDLINE | ID: mdl-37640715

RESUMO

Many RNA viruses employ internal ribosome entry sites (IRESs) in their genomic RNA to commandeer the host's translational machinery for replication. The IRES from encephalomyocarditis virus (EMCV) interacts with eukaryotic translation initiation factor 4 G (eIF4G), recruiting the ribosomal subunit for translation. Here, we analyze the three-dimensional structure of the complex composed of EMCV IRES, the HEAT1 domain fragment of eIF4G, and eIF4A, by cryo-electron microscopy. Two distinct eIF4G-interacting domains on the IRES are identified, and complex formation changes the angle therebetween. Further, we explore the dynamics of these domains by using solution NMR spectroscopy, revealing conformational equilibria in the microsecond to millisecond timescale. In the lowly-populated conformations, the base-pairing register of one domain is shifted with the structural transition of the three-way junction, as in the complex structure. Our study provides insights into the viral RNA's sophisticated strategy for optimal docking to hijack the host protein.


Assuntos
Fator de Iniciação 4G em Eucariotos , RNA Viral , RNA Viral/genética , Microscopia Crioeletrônica , Vírus da Encefalomiocardite/genética , Genômica , Sítios Internos de Entrada Ribossomal
20.
J Alzheimers Dis ; 94(4): 1477-1485, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37393500

RESUMO

BACKGROUND: Most previous studies supported that the mammalian target of rapamycin (mTOR) is over-activated in Alzheimer's disease (AD) and exacerbates the development of AD. It is unclear whether the causal associations between the mTOR signaling-related protein and the risk for AD exist. OBJECTIVE: This study aims to investigate the causal effects of the mTOR signaling targets on AD. METHODS: We explored whether the risk of AD varied with genetically predicted AKT, RP-S6K, EIF4E-BP, eIF4E, eIF4A, and eIF4G circulating levels using a two-sample Mendelian randomization analysis. The summary data for targets of the mTOR signaling were acquired from published genome-wide association studies for the INTERVAL study. Genetic associations with AD were retrieved from the International Genomics of Alzheimer's Project. We utilized the inverse variance weighted as the primary approach to calculate the effect estimates. RESULTS: The elevated levels of AKT (OR = 0.910, 95% CI=0.840-0.986, p = 0.02) and RP-S6K (OR = 0.910, 95% CI=0.840-0.986, p = 0.02) may decrease the AD risk. In contrast, the elevated eIF4E levels (OR = 1.805, 95% CI=1.002-1.174, p = 0.045) may genetically increase the AD risk. No statistical significance was identified for levels of EIF4-BP, eIF4A, and eIF4G with AD risk (p > 0.05). CONCLUSION: There was a causal relationship between the mTOR signaling and the risk for AD. Activating AKT and RP-S6K, or inhibiting eIF4E may be potentially beneficial to the prevention and treatment of AD.


Assuntos
Doença de Alzheimer , Humanos , Doença de Alzheimer/genética , Fator de Iniciação 4E em Eucariotos/genética , Fator de Iniciação 4G em Eucariotos/genética , Estudo de Associação Genômica Ampla , Análise da Randomização Mendeliana , Polimorfismo de Nucleotídeo Único/genética , Proteínas Proto-Oncogênicas c-akt , Serina-Treonina Quinases TOR/genética
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