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1.
Cell Mol Biol Lett ; 29(1): 65, 2024 May 07.
Article in English | MEDLINE | ID: mdl-38714951

ABSTRACT

The engineered clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein (Cas) system is currently widely applied in genetic editing and transcriptional regulation. The catalytically inactivated CasRx (dCasRx) has the ability to selectively focus on the mRNA coding region without disrupting transcription and translation, opening up new avenues for research on RNA modification and protein translation control. This research utilized dCasRx to create a translation-enhancement system for mammals called dCasRx-eIF4GI, which combined eukaryotic translation initiation factor 4G (eIF4GI) to boost translation levels of the target gene by recruiting ribosomes, without affecting mRNA levels, ultimately increasing translation levels of different endogenous proteins. Due to the small size of dCasRx, the dCasRx-eIF4GI translation enhancement system was integrated into a single viral vector, thus optimizing the delivery and transfection efficiency in subsequent applications. Previous studies reported that ferroptosis, mediated by calcium oxalate (CaOx) crystals, significantly promotes stone formation. In order to further validate its developmental potential, it was applied to a kidney stone model in vitro and in vivo. The manipulation of the ferroptosis regulatory gene FTH1 through single-guide RNA (sgRNA) resulted in a notable increase in FTH1 protein levels without affecting its mRNA levels. This ultimately prevented intracellular ferroptosis and protected against cell damage and renal impairment caused by CaOx crystals. Taken together, this study preliminarily validated the effectiveness and application prospects of the dCasRx-eIF4GI translation enhancement system in mammalian cell-based disease models, providing novel insights and a universal tool platform for protein translation research and future therapeutic approaches for nephrolithiasis.


Subject(s)
CRISPR-Cas Systems , Calcium Oxalate , Kidney , Animals , Humans , Male , Mice , Calcium Oxalate/metabolism , CRISPR-Cas Systems/genetics , Eukaryotic Initiation Factor-4G/metabolism , Eukaryotic Initiation Factor-4G/genetics , Ferritins , Ferroptosis/genetics , Gene Editing/methods , HEK293 Cells , Kidney/metabolism , Kidney/pathology , Kidney Calculi/genetics , Kidney Calculi/metabolism , Oxidoreductases/metabolism , Oxidoreductases/genetics , Protein Biosynthesis/genetics , RNA, Guide, CRISPR-Cas Systems/genetics , RNA, Guide, CRISPR-Cas Systems/metabolism
2.
Cancer Lett ; 592: 216950, 2024 Jun 28.
Article in English | MEDLINE | ID: mdl-38729555

ABSTRACT

Malignant pleural mesothelioma is a rare and lethal cancer caused by exposure to asbestos. The highly inflammatory environment caused by fibers accumulation forces cells to undergo profound adaptation to gain survival advantages. Prioritizing the synthesis of essential transcripts is an efficient mechanism coordinated by multiple molecules, including long non-coding RNAs. Enhancing the knowledge about these mechanisms is an essential weapon in combating mesothelioma. Linc00941 correlates to bad prognosis in various cancers, but it is reported to partake in distinct and apparently irreconcilable processes. In this work, we report that linc00941 supports the survival and aggressiveness of mesothelioma cells by influencing protein synthesis and ribosome biogenesis. Linc00941 binds to the translation initiation factor eIF4G, promoting the selective protein synthesis of cMYC, which, in turn, enhances the expression of key genes involved in translation. We analyzed a retrospective cohort of 97 mesothelioma patients' samples from our institution, revealing that linc00941 expression strongly correlates with reduced survival probability. This discovery clarifies linc00941's role in mesothelioma and proposes a unified mechanism of action for this lncRNA involving the selective translation of essential oncogenes, reconciling the discrepancies about its function.


Subject(s)
Eukaryotic Initiation Factor-4G , Gene Expression Regulation, Neoplastic , Lung Neoplasms , Mesothelioma, Malignant , Mesothelioma , Protein Biosynthesis , Proto-Oncogene Proteins c-myc , RNA, Long Noncoding , Humans , Mesothelioma, Malignant/genetics , Mesothelioma, Malignant/pathology , Mesothelioma, Malignant/metabolism , RNA, Long Noncoding/genetics , RNA, Long Noncoding/metabolism , Eukaryotic Initiation Factor-4G/genetics , Eukaryotic Initiation Factor-4G/metabolism , Mesothelioma/genetics , Mesothelioma/pathology , Mesothelioma/metabolism , Cell Line, Tumor , Proto-Oncogene Proteins c-myc/genetics , Proto-Oncogene Proteins c-myc/metabolism , Lung Neoplasms/genetics , Lung Neoplasms/pathology , Lung Neoplasms/metabolism , Pleural Neoplasms/genetics , Pleural Neoplasms/pathology , Pleural Neoplasms/metabolism , Ribosomes/metabolism , Ribosomes/genetics , Retrospective Studies , Prognosis , Cell Proliferation
3.
Mol Cell ; 84(9): 1633-1634, 2024 May 02.
Article in English | MEDLINE | ID: mdl-38701739

ABSTRACT

The heat shock response is crucial for cell survival. In this issue of Molecular Cell, Desroches Altamirano et al.1 demonstrate that a temperature-induced conformational change in the translation initiation factor eIF4G is a key mechanism regulating translation during the heat shock response.


Subject(s)
Eukaryotic Initiation Factor-4G , Heat-Shock Response , Protein Biosynthesis , RNA, Messenger , Eukaryotic Initiation Factor-4G/metabolism , Eukaryotic Initiation Factor-4G/genetics , RNA, Messenger/genetics , RNA, Messenger/metabolism , Humans , Animals , Protein Conformation , Heat-Shock Proteins/metabolism , Heat-Shock Proteins/genetics
4.
Nat Neurosci ; 27(5): 822-835, 2024 May.
Article in English | MEDLINE | ID: mdl-38589584

ABSTRACT

Learning and memory require activity-induced changes in dendritic translation, but which mRNAs are involved and how they are regulated are unclear. In this study, to monitor how depolarization impacts local dendritic biology, we employed a dendritically targeted proximity labeling approach followed by crosslinking immunoprecipitation, ribosome profiling and mass spectrometry. Depolarization of primary cortical neurons with KCl or the glutamate agonist DHPG caused rapid reprogramming of dendritic protein expression, where changes in dendritic mRNAs and proteins are weakly correlated. For a subset of pre-localized messages, depolarization increased the translation of upstream open reading frames (uORFs) and their downstream coding sequences, enabling localized production of proteins involved in long-term potentiation, cell signaling and energy metabolism. This activity-dependent translation was accompanied by the phosphorylation and recruitment of the non-canonical translation initiation factor eIF4G2, and the translated uORFs were sufficient to confer depolarization-induced, eIF4G2-dependent translational control. These studies uncovered an unanticipated mechanism by which activity-dependent uORF translational control by eIF4G2 couples activity to local dendritic remodeling.


Subject(s)
Dendrites , Eukaryotic Initiation Factor-4G , Neurons , Open Reading Frames , Protein Biosynthesis , Animals , Dendrites/metabolism , Eukaryotic Initiation Factor-4G/metabolism , Protein Biosynthesis/physiology , Neurons/metabolism , Open Reading Frames/genetics , Rats , Mice , Cells, Cultured , Potassium Chloride/pharmacology
5.
Cell Rep ; 43(5): 114126, 2024 May 28.
Article in English | MEDLINE | ID: mdl-38630588

ABSTRACT

Scanning and initiation are critical steps in translation. Here, we utilized translation complex profiling (TCP-seq) to investigate 48S organization and eIF4G1-eIF1 inhibition impact. We provide global views of scanning and leaky scanning, uncovering a central role of eIF4G1-eIF1 in their regulation. We confirm AUG context importance, with non-leaky genes featuring a Kozak context and cytosine at positions -1 and +5. Capturing 48S complexes associated with eIF1, eIF4G1, eIF3, and eIF2 through selective TCP-seq revealed that the eIF3-scanning ribosome is highly vulnerable to eIF4G1-eIF1 inhibition, and eIF1 tends to dissociate upon AUG recognition. Initiation-site footprint analysis revealed a class spanning -12 to +18/19 from the AUG, representing the entire 48S and enriched with eIF2, eIF1, and eIF4G1, indicative of early initiation. Another eIF3-dependent class extends up to +26 and exhibits reduced eIF2 and eIF4G1 association, suggesting a late/alternative initiation complex. Our analysis provides an overview of scanning, initiation, and evidence for conformational rearrangements in vivo.


Subject(s)
Ribosomes , Ribosomes/metabolism , Saccharomyces cerevisiae/metabolism , Saccharomyces cerevisiae/genetics , Peptide Chain Initiation, Translational , Humans , Eukaryotic Initiation Factor-4G/metabolism , Eukaryotic Initiation Factor-4G/genetics , Protein Biosynthesis , Saccharomyces cerevisiae Proteins/metabolism , Saccharomyces cerevisiae Proteins/genetics
6.
J Biol Chem ; 300(5): 107242, 2024 May.
Article in English | MEDLINE | ID: mdl-38569933

ABSTRACT

Messenger RNA (mRNA) recruitment to the 40S ribosomal subunit is mediated by eukaryotic initiation factor 4F (eIF4F). This complex includes three subunits: eIF4E (m7G cap-binding protein), eIF4A (DEAD-box helicase), and eIF4G. Mammalian eIF4G is a scaffold that coordinates the activities of eIF4E and eIF4A and provides a bridge to connect the mRNA and 40S ribosomal subunit through its interaction with eIF3. While the roles of many eIF4G binding domains are relatively clear, the precise function of RNA binding by eIF4G remains to be elucidated. In this work, we used an eIF4G-dependent translation assay to reveal that the RNA binding domain (eIF4G-RBD; amino acids 682-720) stimulates translation. This stimulating activity is observed when eIF4G is independently tethered to an internal region of the mRNA, suggesting that the eIF4G-RBD promotes translation by a mechanism that is independent of the m7G cap and mRNA tethering. Using a kinetic helicase assay, we show that the eIF4G-RBD has a minimal effect on eIF4A helicase activity, demonstrating that the eIF4G-RBD is not required to coordinate eIF4F-dependent duplex unwinding. Unexpectedly, native gel electrophoresis and fluorescence polarization assays reveal a previously unidentified direct interaction between eIF4G and the 40S subunit. Using binding assays, our data show that this 40S subunit interaction is separate from the previously characterized interaction between eIF4G and eIF3. Thus, our work reveals how eIF4F can bind to the 40S subunit using eIF3-dependent and eIF3-independent binding domains to promote translation initiation.


Subject(s)
Eukaryotic Initiation Factor-4E , Protein Biosynthesis , Ribosome Subunits, Small, Eukaryotic , Humans , Eukaryotic Initiation Factor-3/chemistry , Eukaryotic Initiation Factor-3/metabolism , Eukaryotic Initiation Factor-4G/metabolism , Protein Binding , Protein Domains , Ribosome Subunits, Small, Eukaryotic/metabolism , Ribosome Subunits, Small, Eukaryotic/genetics , RNA, Messenger/metabolism , RNA, Messenger/genetics , Eukaryotic Initiation Factor-4E/metabolism
7.
Mol Cell ; 84(9): 1727-1741.e12, 2024 May 02.
Article in English | MEDLINE | ID: mdl-38547866

ABSTRACT

Heat-shocked cells prioritize the translation of heat shock (HS) mRNAs, but the underlying mechanism is unclear. We report that HS in budding yeast induces the disassembly of the eIF4F complex, where eIF4G and eIF4E assemble into translationally arrested mRNA ribonucleoprotein particles (mRNPs) and HS granules (HSGs), whereas eIF4A promotes HS translation. Using in vitro reconstitution biochemistry, we show that a conformational rearrangement of the thermo-sensing eIF4A-binding domain of eIF4G dissociates eIF4A and promotes the assembly with mRNA into HS-mRNPs, which recruit additional translation factors, including Pab1p and eIF4E, to form multi-component condensates. Using extracts and cellular experiments, we demonstrate that HS-mRNPs and condensates repress the translation of associated mRNA and deplete translation factors that are required for housekeeping translation, whereas HS mRNAs can be efficiently translated by eIF4A. We conclude that the eIF4F complex is a thermo-sensing node that regulates translation during HS.


Subject(s)
Eukaryotic Initiation Factor-4F , Eukaryotic Initiation Factor-4G , Heat-Shock Response , Poly(A)-Binding Proteins , Protein Biosynthesis , RNA, Messenger , Ribonucleoproteins , Saccharomyces cerevisiae Proteins , Saccharomyces cerevisiae , Saccharomyces cerevisiae Proteins/metabolism , Saccharomyces cerevisiae Proteins/genetics , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Heat-Shock Response/genetics , Eukaryotic Initiation Factor-4F/metabolism , Eukaryotic Initiation Factor-4F/genetics , RNA, Messenger/genetics , RNA, Messenger/metabolism , Eukaryotic Initiation Factor-4G/metabolism , Eukaryotic Initiation Factor-4G/genetics , Ribonucleoproteins/metabolism , Ribonucleoproteins/genetics , Eukaryotic Initiation Factor-4E/metabolism , Eukaryotic Initiation Factor-4E/genetics , Eukaryotic Initiation Factor-4A/metabolism , Eukaryotic Initiation Factor-4A/genetics , Gene Expression Regulation, Fungal , Protein Binding , RNA, Fungal/metabolism , RNA, Fungal/genetics
8.
Phys Chem Chem Phys ; 26(14): 10660-10672, 2024 Apr 03.
Article in English | MEDLINE | ID: mdl-38511550

ABSTRACT

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.


Subject(s)
Eukaryotic Initiation Factor-4E , Eukaryotic Initiation Factor-4G , Humans , Carrier Proteins/metabolism , Eukaryotic Initiation Factor-4E/chemistry , Eukaryotic Initiation Factor-4E/genetics , Eukaryotic Initiation Factor-4E/metabolism , Eukaryotic Initiation Factor-4G/chemistry , Eukaryotic Initiation Factor-4G/genetics , Eukaryotic Initiation Factor-4G/metabolism , Protein Binding , Protein Biosynthesis
9.
Front Endocrinol (Lausanne) ; 15: 1360043, 2024.
Article in English | MEDLINE | ID: mdl-38516410

ABSTRACT

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.


Subject(s)
Puberty, Precocious , TOR Serine-Threonine Kinases , Humans , TOR Serine-Threonine Kinases/genetics , Eukaryotic Initiation Factor-4G , Mendelian Randomization Analysis , Puberty, Precocious/genetics , Causality
10.
Adv Sci (Weinh) ; 11(17): e2309234, 2024 May.
Article in English | MEDLINE | ID: mdl-38380498

ABSTRACT

The CRISPR-Cas system, initially for DNA-level gene editing and transcription regulation, has expanded to RNA targeting with the Cas13d family, notably the RfxCas13d. This advancement allows for mRNA targeting with high specificity, particularly after catalytic inactivation, broadening the exploration of translation regulation. This study introduces a CRISPR-dCas13d-eIF4G fusion module, combining dCas13d with the eIF4G translation regulatory element, enhancing target mRNA translation levels. This module, using specially designed sgRNAs, selectively boosts protein translation in targeted tissue cells without altering transcription, leading to notable protein expression upregulation. This system is applied to a kidney stone disease model, focusing on ferroptosis-linked GPX4 gene regulation. By targeting GPX4 with sgRNAs, its protein expression is upregulated in human renal cells and mouse kidney tissue, countering ferroptosis and resisting calcium oxalate-induced cell damage, hence mitigating stone formation. This study evidences the CRISPR-dCas13d-eIF4G system's efficacy in eukaryotic cells, presenting a novel protein translation research approach and potential kidney stone disease treatment advancements.


Subject(s)
CRISPR-Cas Systems , Calcium Oxalate , Disease Models, Animal , Eukaryotic Initiation Factor-4G , Ferroptosis , Ferroptosis/genetics , Mice , Animals , Calcium Oxalate/metabolism , CRISPR-Cas Systems/genetics , Humans , Eukaryotic Initiation Factor-4G/genetics , Eukaryotic Initiation Factor-4G/metabolism , Kidney Calculi/genetics , Kidney Calculi/metabolism , Protein Biosynthesis/genetics , Phospholipid Hydroperoxide Glutathione Peroxidase/genetics , Phospholipid Hydroperoxide Glutathione Peroxidase/metabolism
11.
Oncogene ; 43(15): 1098-1112, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38388710

ABSTRACT

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.


Subject(s)
Endometrial Neoplasms , Kinesins , Female , Humans , Kinesins/genetics , Proteomics , Cell Line , Endometrial Neoplasms/genetics , Endometrial Neoplasms/pathology , Eukaryotic Initiation Factor-4G/genetics , Eukaryotic Initiation Factor-4G/metabolism
12.
J Orthop Surg Res ; 19(1): 134, 2024 Feb 12.
Article in English | MEDLINE | ID: mdl-38342889

ABSTRACT

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.


Subject(s)
MicroRNAs , Osteoarthritis , Humans , Osteogenesis/genetics , MicroRNAs/genetics , MicroRNAs/metabolism , Cell Differentiation/genetics , Osteoblasts/metabolism , Luciferases/metabolism , Osteoarthritis/metabolism , Cells, Cultured , Eukaryotic Initiation Factor-4G/metabolism
13.
Sci Rep ; 14(1): 2178, 2024 01 25.
Article in English | MEDLINE | ID: mdl-38272944

ABSTRACT

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.


Subject(s)
Eukaryotic Initiation Factor-4F , Trypanosoma brucei brucei , Eukaryotic Initiation Factor-4F/metabolism , Eukaryotic Initiation Factor-4G/metabolism , Eukaryotic Initiation Factor-4E/metabolism , Trypanosoma brucei brucei/genetics , Protein Binding , RNA, Messenger/metabolism
14.
Sci Rep ; 14(1): 251, 2024 01 02.
Article in English | MEDLINE | ID: mdl-38167853

ABSTRACT

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.


Subject(s)
Eukaryotic Initiation Factor-4G , RNA-Binding Proteins , Animals , Humans , RNA, Messenger/genetics , RNA, Messenger/metabolism , Eukaryotic Initiation Factor-4G/genetics , Eukaryotic Initiation Factor-4G/metabolism , RNA-Binding Proteins/genetics , RNA-Binding Proteins/metabolism , RNA , Mammals/genetics , Mammals/metabolism
16.
Thorac Cancer ; 15(1): 44-56, 2024 Jan.
Article in English | MEDLINE | ID: mdl-37993106

ABSTRACT

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.


Subject(s)
Carcinoma, Non-Small-Cell Lung , Lung Neoplasms , MicroRNAs , Humans , Carcinoma, Non-Small-Cell Lung/genetics , Lung Neoplasms/genetics , Apoptosis , Cell Count , Cell Proliferation , MicroRNAs/genetics , Eukaryotic Initiation Factor-4G/genetics
17.
Nat Cancer ; 5(1): 30-46, 2024 Jan.
Article in English | MEDLINE | ID: mdl-37845485

ABSTRACT

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.


Subject(s)
Adenocarcinoma , Colonic Neoplasms , Humans , RNA, Circular , Cardiolipins , Proto-Oncogene Proteins p21(ras) , RNA, Messenger/genetics , Eukaryotic Initiation Factor-4G/genetics , Eukaryotic Initiation Factor-4G/metabolism , Heterogeneous-Nuclear Ribonucleoproteins/genetics , Polypyrimidine Tract-Binding Protein/genetics , Polypyrimidine Tract-Binding Protein/metabolism
18.
Phys Chem Chem Phys ; 26(3): 2073-2081, 2024 Jan 17.
Article in English | MEDLINE | ID: mdl-38131207

ABSTRACT

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.


Subject(s)
Eukaryotic Initiation Factor-4E , Eukaryotic Initiation Factor-4G , Eukaryotic Initiation Factor-4E/chemistry , Eukaryotic Initiation Factor-4E/genetics , Eukaryotic Initiation Factor-4E/metabolism , Eukaryotic Initiation Factor-4G/chemistry , Eukaryotic Initiation Factor-4G/genetics , Eukaryotic Initiation Factor-4G/metabolism , Molecular Dynamics Simulation , Protein Biosynthesis , Saccharomyces cerevisiae , Protein Binding
19.
Life Sci Alliance ; 7(3)2024 Mar.
Article in English | MEDLINE | ID: mdl-38129098

ABSTRACT

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.


Subject(s)
Neoplasms , Protein Biosynthesis , Humans , Protein Biosynthesis/genetics , Mutation/genetics , Neoplasms/genetics , Eukaryotic Initiation Factor-4G/genetics , Tumor Microenvironment
20.
PLoS Pathog ; 19(11): e1011417, 2023 Nov.
Article in English | MEDLINE | ID: mdl-37983287

ABSTRACT

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.


Subject(s)
Arabidopsis Proteins , Arabidopsis , Potyvirus , Arabidopsis/metabolism , Eukaryotic Initiation Factor-4E/genetics , Eukaryotic Initiation Factor-4E/metabolism , Potyvirus/physiology , Plants, Genetically Modified/metabolism , Plant Diseases/genetics , Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , Eukaryotic Initiation Factor-4G/metabolism
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