Search Results (138)

Cell-based immunotherapy is a promising treatment strategy for cancer. Particularly in the case of solid tumors, however, this strategy only benefits a minority of patients. A critical limitation to immunotherapy is T cell exhaustion, a terminal differentiation state characterized by loss of self-renewal and cytotoxic capacity. For over a decade, regenerative immunology approaches to overcome exhaustion and restore stem-like features of T cells have been pursued. The reprogramming of tumor-specific T cells back to a less-differentiated, stem-like state using induced pluripotent stem cell (iPSC) technology has been viewed as a powerful and highly appealing strategy to overcome the limitations imposed by exhaustion. However, clinical translation of these approaches has been stymied by the requirement for subsequent iPSC-to-T cell re-maturation strategies, vanishingly low efficiencies, and resource-intensive cell culture protocols. In this review, we discuss the emergence of transcription factor reprogramming to iPSCs, contemporary techniques for T cell reprogramming, as well as techniques for re-differentiation into mature T cells. We discuss the potential clinical utility of T cell reprogramming and re-maturation strategies alongside progress and major roadblocks toward clinical translation. If these challenges can be addressed, transcription factor reprogramming of T cells into iPSCs and subsequent re-maturation into tumor-specific stem-like T cells may represent an incredibly efficacious approach to cancer immunotherapy. Full article

Background/Objectives: PAX3 is a transcription factor that drives melanoma progression by promoting cell growth, migration, and survival, while inhibiting cellular terminal differentiation. However, known PAX3 target genes are limited and cannot fully explain the wide impact of PAX3 function. The PAX3 protein can regulate DNA through two separate binding domains, the Paired Domain (PD) and Homeodomain (HD), which bind different DNA motifs. It is not clear if these two domains bind and work together to regulate genes and if they promote all or only a subset of downstream cellular events. Methods: PAX3 direct downstream targets were identified using Cleavage Under Targets & Release Using Nuclease (CUT&RUN) assays in SK-MEL-5 melanoma cells. PAX3-binding genomic regions were identified through MACS2 peak calling, and peaks were categorized based on the presence of PD and/or HD binding sites (or neither) through HOMER motif analysis. The peaks were further characterized as Active, Primed, Poised, Repressed, or Closed based on ATAC-seq data and CUT&RUN for histone Post-Translational Modifications H3K4me1, H3K4me3, H3K27me3, and H3K27Ac. Results: This analysis revealed that most of the PAX3 binding sites in the SK-MEL-5 cell line were primarily through the PD and connected to Active genes. Surprisingly, PAX3 does not commonly act as a repressor in SK-MEL-5 cells. Pathway analysis identified genes involved with transcription, RNA modification, and cell growth. Peaks located in distal enhancer elements were connected to genes involved in neuronal growth, function, and signaling. Conclusions: Our results reveal novel PAX3 regulatory regions and putative genes in a melanoma cell line, with a predominance of PAX3 PD binding on active sites. Full article

Burkholderia lethal factor 1 (BLF1), a toxin derived from Burkholderia pseudomallei, reacts with eukaryotic initiation factor (eIF) 4A to inhibit protein synthesis. eIF4A1 and eIF4A2 are involved in translation initiation and share over 90% sequence similarity. However, they exert distinct effects on cancer treatment outcomes. To understand the molecular mechanism by which BLF1 modulates eIF4A isoforms in cancer cells, we investigated its effects on eIF4A-mediated adenosine 5′-triphosphate (ATP) hydrolysis. We found that eIF4A1 has a higher ATP-binding affinity compared to eIF4A2 (K_m = 6.55 ± 0.78 μM vs. K_m = 11.61 ± 2.33 μM). Meanwhile, we also found that eIF4A1 is more sensitive to changes in temperature, pH, and Mg²⁺ concentration. Through N-terminal swapping and single amino acid mutations, we found that leucine 98 (L98) and alanine 100 (A100) play important roles in the ATPase activities of eIF4A isoforms. Moreover, BLF1 treatment significantly enhanced eIF4A2-mediated ATP hydrolysis at all tested ATP concentrations. These differences in BLF1-regulated eIF4A isoforms may explain its selective cytotoxicity against cancer cells. Our findings provide molecular insights into the functional difference between eIF4A isoforms and suggest that BLF1 might be of promising value for anticancer therapies. Full article

The essential SUP35 gene encodes yeast translation termination factor Sup35/eRF3. The N-terminal domain of Sup35 is also responsible for Sup35 prionization that leads to generation of the [PSI⁺] prion. Previously we isolated different types of sup35 mutations (missense and nonsense) and demonstrated that sup35 nonsense mutations (sup35-n) are incompatible with the [PSI⁺] prion, leading to lethality of sup35-n [PSI⁺] haploid cells. Here, we show that sup35 missense mutations (sup35-m) within conservative regions of the Sup35 C-domain result in lethality of [PSI⁺] cells because of weak activity of Sup35/eRF3 as a translation termination factor. Mutant Sup35 maintain their ability to be incorporated into pre-existing [PSI⁺] aggregates and to form amyloid aggregates in vitro, while sup35-m mutations do not influence the [PSI⁺] prion induction and stability. All these mutations (D363N, R372K, T378I) are located in the conservative GTPase region of Sup35, decreasing the GTPase activity of mutated proteins. We propose that such low activity of mutant Sup35 combined with aggregation of Sup35 constituting the [PSI⁺] prion is not sufficient to maintain the viability of yeast cells. Full article

The growth of breast tumors is driven and controlled by a subpopulation of cancer cells resembling adult stem cells, which are called cancer stem-like cells (CSCs). In breast cancer, the function and maintenance of CSCs are influenced by protein O-GlcNAcylation and the enzyme responsible for this post-translational modification, O-GlcNAc transferase (OGT). However, the mechanism of CSCs regulation by OGT and O-GlcNAc cycling in breast cancer is still unclear. Analysis of the proteome and O-GlcNAcome, revealed GATAD2B, a component of the Nucleosome Remodeling and Deacetylase (NuRD) complex, as a substrate regulated by OGT. Reducing GATAD2B genetically impairs mammosphere formation, decreases expression of self-renewal factors and CSCs population. O-GlcNAcylation of GATAD2B at the C-terminus protects GATAD2B from ubiquitination and proteasomal degradation in breast cancer cells. We identify ITCH as a novel E3 ligase for GATAD2B and show that targeting ITCH genetically increases GATAD2B levels and increases CSCs phenotypes. Lastly, we show that overexpression of wild-type GATAD2B, but not the mutant lacking C-terminal O-GlcNAc sites, promotes mammosphere formation, expression of CSCs factors and drug resistance. Together, we identify a key role of GATAD2B and ITCH in regulating CSCs in breast cancer and GATAD2B O-GlcNAcylation as a mechanism regulating breast cancer stem-like populations and promoting chemoresistance. Full article

3,4-Dihydroxy-L-phenylalanine (DOPA) is a promising noncanonical amino acid (ncAA) that introduces novel catechol chemical features into proteins, expanding their functional potential. However, the most common approach to incorporating ncAAs into proteins relies on stop codon suppression, which is often limited by the competition of endogenous translational termination machinery. Here, we employed a special in vitro protein expression system that facilitates the efficiency of DOPA incorporation into proteins by removing essential Class I peptide release factors through targeted degradation. In the absence of both RF1 and RF2, we successfully demonstrated DOPA incorporation at all three stop codons (TAG, TAA, and TGA). By optimizing the concentration of engineered DOPA-specific aminoacyl-tRNA synthetase (DOPARS), DOPA, and DNA template, we achieved a synthesis yield of 2.24 µg of sfGFP with 100% DOPA incorporation in a 20 μL reaction system. DOPARS exhibited a dissociation constant (Kd) of 11.7 μM for DOPA but showed no detectable binding to its native counterpart, tyrosine. Additionally, DOPA was successfully incorporated into a reverse transcriptase, which interfered with its activity. This system demonstrates a fast and efficient approach for precise DOPA incorporation into proteins, paving the way for advanced protein engineering applications. Full article

ORF2p (open reading frame 2 protein) is a multifunctional multidomain enzyme that demonstrates both reverse transcriptase and endonuclease activities and is associated with the pathophysiology of cancer. The 3D structure of the entire seven-domain ORF2p complex was revealed with the recent achievements in structural studies. The different arrangements of the CTD (carboxy-terminal domain) and tower domains were identified as the “closed-ring” and “open-ring” conformations, which differed by the hairpin position of the tower domain, but the structural diversity of these complexes has the potential to be more extensive. To study this, we performed sub-microsecond all-atom molecular dynamics simulations of the entire ORF2p complex with different starting configurations. The obtained molecular dynamic trajectories frames were assigned to several clusters following the dimension reduction to three principal components of the 1275 distances feature matrix. Five and six clusters were obtained for the “open” and “closed” ring models, respectively. While the fingers–palm–thumb core retains its rigid configuration during the MD (molecular dynamics) simulations, all other domains display the complicated dynamic behavior not observed in the experimental structures. The EN (endonuclease) and CTD domains display significant translations and rotations while their internal structures stay rigid. The CTD domain can either form strong contacts with the tower or be far apart from it for both formal “open” and “closed” ring states because the tower hairpin position is not the only determining factor of the protein complex configuration. While only the “thumb up” conformation is observed in all the trajectories, the active site can be obstructed by the movement of the CTD domain. Thus, molecular modeling and machine learning techniques provide valuable insights into the dynamical behavior of the ORF2p complex, which is hard to uncover with experimental methods, given the complexity and size of the object. Full article

Background: Crohn’s disease (CD) is a complex systemic entity, characterized by the progressive and relapsing inflammatory involvement of any part of the gastrointestinal tract. Its clinical pattern may be categorized as penetrating, stricturing or non-penetrating non-stricturing. Methods: In this paper, we performed a database search (Pubmed, MEDLINE, Mendeley) using combinations of the queries “crohn”, “stricture” and “elastography” up to 19 June 2024 to summarize current knowledge regarding the diagnostic utility of ultrasound (US) and magnetic resonance (MR) elastography techniques in the evaluation of stricturing CD by means of an assessment of the transmural intestinal fibrosis. We decided to include papers published since 1 January 2017 for further evaluation (n = 24). Results: Despite growing collective and original data regarding numerous applications of mostly ultrasound elastography (quantification of fibrosis, distinguishing inflammatory from predominantly fibrotic strictures, assessment of treatment response, predicting disease progression) constantly emerging, to date, we are still lacking a uniformization in both cut-off values and principles of measurements, i.e., reference tissue in strain elastography (mesenteric fat, abdominal muscles, unaffected bowel segment), units, not to mention subtle differences in technical background of SWE techniques utilized by different vendors. All these factors imply that ultrasound elastography techniques are hardly translatable throughout different medical centers and practitioners, largely depending on the local experience. Conclusions: Nonetheless, the existing medical evidence is promising, especially in terms of possible longitudinal comparative studies (follow-up) of patients in the course of the disease, which seems to be of particular interest in children (lack of radiation, less invasive contrast media) and terminal ileal disease (easily accessible). Full article

FMS-like tyrosine kinase 3 (FLT3) internal tandem duplication (ITD) mutations in acute myeloid leukemia (AML) are associated with poor prognosis and therapy resistance. This study aimed to demonstrate that inhibiting the deubiquitinating enzymes ubiquitin-specific peptidase 14 (USP14) and ubiquitin C-terminal hydrolase L5 (UCHL5) (USP14/UCHL5) with b-AP15 or the organogold compound auranofin (AUR) induces apoptosis in the ITD-transformed human leukemia cell line MV4-11 and mononuclear leukocytes derived from patients with FLT3-ITD-positive AML. This study included patients diagnosed with AML at Tokyo Medical and Dental University Hospital between January 2018 and July 2024. Both treatments blocked downstream FLT3 pathway events, with the effects potentiated by USP14 knockdown. Both treatments inhibited FLT3 deubiquitination via K48 and disrupted translation initiation via 4EBP1, a downstream FLT3 target. FLT3 was downregulated in the leukemic cells, with the associated activation of stress-related MAP kinase pathways and increased NF-E2-related factor 2. Furthermore, the overexpression of B-cell lymphoma-extra-large and myeloid cell leukemia-1 prevented the cell death caused by b-AP15 and AUR. These results suggest that inhibiting USP14/UCHL5, which involves multiple regulatory mechanisms, is a promising target for novel therapies for treatment-resistant FLT3-ITD-positive AML. Full article

Caliciviruses have positive-sense RNA genomes, typically with short 5′-untranslated regions (5′UTRs) that precede the long open reading frame 1 (ORF1). Exceptionally, some avian caliciviruses have long 5′UTRs containing a picornavirus-like internal ribosomal entry site (IRES), which was likely acquired by horizontal gene transfer. Here, we identified numerous additional avian calicivirus genomes with IRESs, predominantly type 2, and determined that many of these genomes contain a ~200–300 codon-long ORF (designated ORF1*) that overlaps the 5′-terminal region of ORF1. The activity of representative type 2 IRESs from grey teal calicivirus (GTCV) and Caliciviridae sp. isolate yc-13 (RaCV1) was confirmed by in vitro translation. Toeprinting showed that in cell-free extracts and in vitro reconstituted reactions, ribosomal initiation complexes assembled on the ORF1* initiation codon and at one or two AUG codons in ORF1 at the 3′-border and/or downstream of the IRES. Initiation at all three sites required eIF4A and eIF4G, which bound to a conserved region of the IRES; initiation on the ORF1* and principal ORF1 initiation codons involved eIF1/eIF1A-dependent scanning from the IRES’s 3′-border. Initiation on these IRESs was enhanced by the IRES trans-acting factors (ITAFs) Ebp1/ITAF₄₅, which bound to the apical subdomain Id of the IRES, and PTB (GTCV) or PCBP2 (RaCV1). Full article

In today’s world, air transport has become a favored choice for enhancing the value of a national economy, driven by advancing technology, escalating volumes of national and international trade, and population growth. The proliferation of airport transfer centers, particularly within air transport, plays a pivotal role in fostering the advancement of the aviation sector. Therefore, the selection of these hubs is of great importance. This study evaluated the New Çukurova, Antalya, Sivas Nuri Demirağ, Erzurum and Muğla Airports in Türkiye for the selection of a new airport transfer center in terms of criteria such as airport costs, airport terminal and apron facilities, airport passenger transportation services, airport operating capacity, airport location, demand factors in the service region and other factors. The study employed three methods for evaluating alternative international airports: AHP (Analytic Hierarchy Process), MOORA (Multi-Objective Optimization by Ratio Analysis) and ELECTRE (Elimination and Choice Translating Reality). In the initial phase, the priority ranking of criteria was established based on expert opinions. Subsequently, Antalya Airport was the most suitable airport transfer center according to the ELECTRE method, while New Çukurova Airport emerged as the preferred choice according to the MOORA method. Both airports secured top rankings in both evaluation methods. Full article

The unique amino acid hypusine [N^ε-(4-amino-2-hydroxybutyl)lysine] is exclusively formed on the translational regulator eukaryotic initiation factor 5A (eIF5A) via a process coined hypusination. Hypusination is mediated by two enzymes, deoxyhypusine synthase (DHPS) and deoxyhypusine hydroxylase (DOHH), and hypusinated eIF5A (eIF5A^Hyp) promotes translation elongation by alleviating ribosome pauses at amino acid motifs that cause structural constraints, and it also facilitates translation initiation and termination. Accordingly, eIF5A^Hyp has diverse biological functions that rely on translational control of its targets. Homozygous deletion of Eif5a, Dhps, or Dohh in mice leads to embryonic lethality, and heterozygous germline variants in EIF5A and biallelic variants in DHPS and DOHH are associated with rare inherited neurodevelopmental disorders, underscoring the importance of the hypusine circuit for embryonic and neuronal development. Given the pleiotropic effects of eIF5A^Hyp, a detailed understanding of the cell context-specific intrinsic roles of eIF5A^Hyp and of the chronic versus acute effects of eIF5A^Hyp inhibition is necessary to develop future strategies for eIF5A^Hyp-targeted therapy to treat various human health problems. Here, we review the most recent studies documenting the intrinsic roles of eIF5A^Hyp in different tissues/cell types under normal or pathophysiological conditions and discuss these unique aspects of eIF5A^Hyp-dependent translational control. Full article

Eukaryotic release factor eRF1, encoded by the ETF1 gene, recognizes stop codons and induces peptide release during translation termination. ETF1 produces several different transcripts as a result of alternative splicing, from which two eRF1 isoforms can be formed. Isoform 1 codes well-studied canonical eRF1, and isoform 2 is 33 amino acid residues shorter than isoform 1 and completely unstudied. Using a reconstituted mammalian in vitro translation system, we showed that the isoform 2 of human eRF1 is also involved in translation. We showed that eRF1iso2 can interact with the ribosomal subunits and pre-termination complex. However, its codon recognition and peptide release activities have decreased. Additionally, eRF1 isoform 2 exhibits unipotency to UGA. We found that eRF1 isoform 2 interacts with eRF3a but stimulated its GTPase activity significantly worse than the main isoform eRF1. Additionally, we studied the eRF1 isoform 2 effect on stop codon readthrough and translation in a cell-free translation system. We observed that eRF1 isoform 2 suppressed stop codon readthrough of the uORFs and decreased the efficiency of translation of long coding sequences. Based on these data, we assumed that human eRF1 isoform 2 can be involved in the regulation of translation termination. Moreover, our data support previously stated hypotheses that the GTS loop is important for the multipotency of eRF1 to all stop codons. Whereas helix α1 of the N-domain eRF1 is proposed to be involved in conformational rearrangements of eRF1 in the A-site of the ribosome that occur after GTP hydrolysis by eRF3, which ensure hydrolysis of peptidyl-tRNA at the P site of the ribosome. Full article

Eukaryotic translation initiation factors (eIFs) are crucial for initiating protein translation and ensuring the correct assembly of mRNA-ribosomal subunit complexes. In this study, we investigated the effects of deleting six eIFs in the apicomplexan parasite Toxoplasma gondii using the CRISPR-Cas9 system. We determined the subcellular localization of these eIFs using C-terminal endogenous tagging and immunofluorescence analysis. Four eIFs (RH::315150-6HA, RH::286090-6HA, RH::249370-6HA, and RH::211410-6HA) were localized in the cytoplasm, while RH::224235-6HA was localized in the apicoplast. Additionally, RH::272640-6HA was found in both the basal complex and the cytoplasm of T. gondii. Functional characterization of the six RHΔeIFs strains was conducted using plaque assay, cell invasion assay, intracellular growth assay and egress assay in vitro, and virulence assay in mice. Disruption of five eIF genes (RHΔ315150, RHΔ272640, RHΔ249370, RHΔ211410, and RHΔ224235) did not affect the ability of the T. gondii RH strain to invade, replicate, form plaques and egress in vitro, or virulence in Kunming mice (p > 0.05). However, the RHΔ286090 strain showed slightly reduced invasion efficiency and virulence (p < 0.01) compared to the other five RHΔeIFs strains and the wild-type strain. The disruption of the TGGT1_286090 gene significantly impaired the ability of tachyzoites to differentiate into bradyzoites in both type I RH and type II Pru strains. These findings reveal that the eukaryotic translation initiation factor TGGT1_286090 is crucial for T. gondii bradyzoite differentiation and may serve as a potential target for drug development and an attenuated vaccine against T. gondii. Full article

Circadian oscillations of several physiological and behavioral processes are an established process in all the organisms anticipating the geophysical changes recurring during the day. The time-keeping mechanism is controlled by a transcription translation feedback loop involving a set of well-characterized transcription factors. The synchronization of cells, controlled at the organismal level by a brain central clock, can be mimicked in vitro, pointing to the notion that all the cells are endowed with an autonomous time-keeping system. Metabolism undergoes circadian control, including the mitochondrial terminal catabolic pathways, culminating under aerobic conditions in the electron transfer to oxygen through the respiratory chain coupled to the ATP synthesis according to the oxidative phosphorylation chemiosmotic mechanism. In this study, we expanded upon previous isolated observations by utilizing multiple cell types, employing various synchronization protocols and different methodologies to measure mitochondrial oxygen consumption rates under conditions simulating various metabolic stressors. The results obtained clearly demonstrate that mitochondrial respiratory activity undergoes rhythmic oscillations in all tested cell types, regardless of their individual respiratory proficiency, indicating a phenomenon that can be generalized. However, notably, while primary cell types exhibited similar rhythmic respiratory profiles, cancer-derived cell lines displayed highly heterogeneous rhythmic changes. This observation confirms on the one hand the dysregulation of the circadian control of the oxidative metabolism observed in cancer, likely contributing to its development, and on the other hand underscores the necessity of personalized chronotherapy, which necessitates a detailed characterization of the cancer chronotype. Full article