eIF4E phosphorylation recruits β-catenin to mRNA cap and promotes Wnt pathway translation in dentate gyrus LTP maintenance

Potential therapeutic targets of eukaryotic translation initiation factors in tumor therapy

Translation initiation is the first and rate-limiting step in protein synthesis, and its dysregulation is frequently observed in various malignancies. Cap-dependent translation, the predominant form of translation initiation, relies on the coordinated action of eukaryotic translation initiation factors (eIFs), including eIF1, eIF2, eIF4, and others. These factors play critical roles in regulating the efficiency and fidelity of protein synthesis, and their overexpression has been linked to tumor progression, proliferation, and metastasis. Notably, certain eIFs have emerged as potential prognostic markers due to their elevated expression in tumors. Targeting eIFs represents a promising strategy, particularly for cancers characterized by aberrant eIF activity. In this review, we summarize the roles of individual eIFs in cap-dependent translation and discuss their potential as therapeutic targets in cancer treatment. We also highlight recent advances in drug discovery efforts aimed at modulating eIF activity, providing insights into the development of novel anticancer therapies.

Neuronal potassium channel activity triggers initiation of mRNA translation through binding of translation regulators

Neuronal activity stimulates mRNA translation crucial for learning and development, but the mechanism linking translation to neuronal activity is not understood. In humans, learning and memory are severely disrupted by mutations in the potassium channel Slack (KCNT1, Slo2.2). We find that pharmacological stimulation of this channel and a constitutively active Slack mutation stimulate mRNA translation of a reporter for β-actin mRNA in cell lines and increases the synthesis of β-actin in the neurites of cortical neurons. Moreover, channel activation promotes the binding of two key mRNA translation regulators, FMRP (fragile X mental retardation protein) and CYFIP1 (cytoplasmic FMR1-interacting protein 1), to the channel itself, releasing both from eIF4E (eukaryotic initiation factor 4E), where they normally inhibit initiation of translation. This interaction provides a molecular mechanism for Slack activity-dependent regulation of translation and suggests that the effects of Slack mutations on this process may explain the severe intellectual disabilities associated with these mutations.

β-Catenin interacts with canonical RBPs including MSI2 to associate with a Wnt signalling mRNA network in myeloid leukaemia cells

Wnt/β-catenin signalling is important for normal hematopoietic stem/progenitor cell (HSPC) biology and heavily implicated in acute and chronic myeloid leukaemia (AML and CML). The central mediator β-catenin is an attractive therapeutic target in myeloid neoplasms however its targeting has been hampered by a poor characterisation of its molecular interactions in haematopoietic cells, which will differ from its network in solid tissues. Our previous β-catenin interactome study identified the significant enrichment of RNA-binding proteins (RBP) implying post-transcriptional roles for β-catenin in myeloid cells. To identify β-catenin interacting mRNAs we performed β-catenin RNA-immunoprecipitation coupled to RNA-sequencing (RIP-seq) and identified significantly enriched Wnt signalling pathway transcripts. Using β-catenin cross-linking immunoprecipitation (CLIP) we demonstrated a limited capacity for β-catenin to bind RNA directly, implying dependence on other RBPs. β-Catenin was found to interact with Musashi-2 (MSI2) in both myeloid cell lines and primary AML patient samples, where expression was significantly correlated. MSI2 knockdown reduced Wnt signalling output (TCF/LEF activity), through suppression of LEF-1 expression and nuclear localisation. Through both RIP and CLIP we demonstrate MSI2 binds LEF1 mRNA in a partly β-catenin dependent fashion, and may impact the post-transcriptional control of LEF-1 expression. Finally, we show that MSI2-mediated expansion of human HSPCs could be partly driven through LEF1 regulation. This is the first study to experimentally demonstrate functional crosstalk between MSI2 and Wnt signalling in human cells, and indicates potential novel post-transcriptional roles for β-catenin in a haematological context.

Disruptions in cellular communication: Molecular interplay between glutamate/NMDA signalling and MAPK pathways in neurological disorders

Neurological disorders significantly impact the central nervous system, contributing to a growing public health crisis globally. The spectrum of these disorders includes neurodevelopmental and neurodegenerative diseases. This manuscript reviews the crucial roles of cellular signalling pathways in the pathophysiology of these conditions, focusing primarily on glutaminase/glutamate/NMDA receptor signalling, alongside the mitogen-activated protein kinase (MAPK) pathways-ERK1/2, C-JNK, and P38 MAPK. Activation of these pathways is often correlated with neuronal excitotoxicity, apoptosis, and inflammation, leading to many other pathological conditions such as traumatic brain injury, stroke, and brain tumor. The interplay between glutamate overstimulation and MAPK signalling exacerbates neurodegenerative processes, underscoring the complexity of cellular communication in maintaining neuronal health. Dysfunctional signalling alters synaptic plasticity and neuronal survival, contributing to cognitive impairments in various neurological diseases. The manuscript emphasizes the potential of targeting these signalling pathways for therapeutic interventions, promoting neuroprotection and reducing neuroinflammation. Incorporating insights from precision medicine and innovative drug delivery systems could enhance treatment efficacy. Overall, understanding the intricate mechanisms of these pathways is essential for developing effective strategies to mitigate the impact of neurological disorders and improve patient outcomes. This review highlights the necessity for further exploration into these signalling cascades to facilitate advancements in therapeutic approaches, ensuring better prognoses for individuals affected by neurological conditions.

Unlocking Hope: Therapeutic Advances and Approaches in Modulating the Wnt Pathway for Neurodegenerative Diseases

Neurodegenerative diseases (NDs) are conditions characterized by sensory, motor, and cognitive impairments due to alterations in the structure and function of neurons in the central nervous system (CNS). Despite their widespread occurrence, the exact causes of NDs remain largely elusive, and existing treatments fall short in efficacy. The Wnt signaling pathway is an emerging molecular pathway that has been linked to the development and progression of various NDs. Wnt signaling governs numerous cellular processes, such as survival, polarity, proliferation, differentiation, migration, and fate specification, via a complex network of proteins. In the adult CNS, Wnt signaling regulates synaptic transmission, plasticity, memory formation, neurogenesis, neuroprotection, and neuroinflammation, all essential for maintaining neuronal function and integrity. Dysregulation of both canonical and non-canonical Wnt signaling pathways contributes to neurodegeneration through various mechanisms, such as amyloid-β accumulation, tau protein hyperphosphorylation, dopaminergic neuron degeneration, and synaptic dysfunction, prompting investigations into Wnt modulation as a therapeutic target to restore neuronal function and prevent or delay neurodegenerative processes. Modulating Wnt signaling has the potential to restore neuronal function and impede or postpone neurodegenerative processes, offering a therapeutic approach for targeting NDs. In this article, the current knowledge about how Wnt signaling works in Alzheimer's disease and Parkinson's disease is discussed. Our study aims to explore the molecular mechanisms, recent discoveries, and challenges involved in developing Wnt-based therapies.

EIF4E-mediated biogenesis of circPHF14 promotes the growth and metastasis of pancreatic ductal adenocarcinoma via Wnt/β-catenin pathway

BACKGROUND

CircRNAs are critically involved in the development and progression of various cancers. However, their functions and mechanisms in pancreatic ductal adenocarcinoma (PDAC) remain largely unknown.

METHODS

CircPHF14 (hsa_circ_0079440) was identified through the analysis of RNA sequencing data from PDAC and normal adjacent tissues. The biological functions of circPHF14 were then evaluated using CCK8, EdU, transwell, colony formation, wound healing assays, as well as pancreatic orthotopic xenograft and liver metastasis models. The interaction mechanisms between circPHF14 and PABPC1, which enhance the stability of WNT7A mRNA, were investigated through RNA pull-down, mass spectrometry, RNA Immunoprecipitation (RIP), and actinomycin D assays. The role of EIF4E in promoting circPHF14 biogenesis was examined using RIP, and western blotting.

RESULTS

In this study, we observed a significant upregulation of circPHF14 in both clinical PDAC samples and cell lines. Functionally, circPHF14 enhanced PDAC proliferation and metastasis both in vitro and in vivo. Mechanistically, circPHF14 interacted with PABPC1 to stabilize WNT7A mRNA, thereby activating the Wnt/β-catenin pathway, which subsequently upregulated SNAI2 and initiated Epithelial-Mesenchymal Transition (EMT) in PDAC. Additionally, EIF4E was found to bind PHF14 pre-mRNA, facilitating circPHF14 biogenesis. Finally, we developed a lipid nanoparticle (LNP) formulation encapsulating sh-circPHF14 plasmids and confirmed its anti-tumor efficacy in a patient-derived xenograft (PDX) model.

CONCLUSION

EIF4E-mediated biogenesis of circPHF14 stabilizes WNT7A mRNA via interaction with PABPC1, which subsequently activates the Wnt/β-catenin pathway, promoting the growth and metastasis of PDAC. These findings indicate that circPHF14 holds promise as a biomarker and therapeutic target for PDAC.

Identification and Validation of Biomarkers for Alzheimer's Disease Based on Akt and Wnt Signaling Pathways in Mouse Models

Alzheimer's disease (AD) is a neurodegenerative disease that remains challenging to treat. Akt and Wnt play a role in complex cellular signaling, which is crucial for examining the onset of AD. In this study, we aimed to identify and analyze Akt pathway-related genes (ARGs) and Wnt pathway-related genes (WRGs) as AD biomarkers, determine the effects of ARGs and WRGs on AD, and verify these effects in AD mouse models. We searched for differentially expressed genes in the Gene Expression Omnibus database, constructed candidate gene protein-protein interaction networks, and used least absolute shrinkage and selection operator regression analysis and the support vector machine-recursive feature elimination algorithm to screen key genes. Correlation and functional similarity analyses of key genes, immune infiltration analysis, competing endogenous RNA network construction, and drug prediction of key genes were performed. Expression of key genes in streptozotocin-treated (STZ)-treated AD mice was validated using quantitative reverse transcription polymerase chain reaction (RT-qPCR). Bioinformatics analysis identified five key genes in AD: PRKACA, CDH3, ATP6V0C, DLL1, and CELSR2. Step-down tests, immunohistochemistry, and silver plate staining confirmed successful treatment of STZ-induced AD in mice. According to RT-qPCR analysis, the relative expression of DLL1 mRNA in AD mice was higher than that in control mice, whereas the relative expression of ATP6V0C and PRKACA mRNA in AD mice was lower than that in control mice; this was consistent with the results of bioinformatics analysis (p < 0.05). This study screened and validated AD biomarkers associated with the Akt and Wnt pathways in mouse models.

Visualizing Arc protein dynamics and localization in the mammalian brain using AAV-mediated in situ gene labeling

The activity-regulated cytoskeleton-associated (Arc) protein is essential for synaptic plasticity and memory formation. The Arc gene, which contains remnants of a structural GAG retrotransposon sequence, produces a protein that self-assembles into capsid-like structures harboring Arc mRNA. Arc capsids, released from neurons, have been proposed as a novel intercellular mechanism for mRNA transmission. Nevertheless, evidence for intercellular transport of Arc in the mammalian brain is still lacking. To enable the tracking of Arc molecules from individual neurons in vivo, we devised an adeno-associated virus (AAV) mediated approach to tag the N-terminal of the mouse Arc protein with a fluorescent reporter using CRISPR/Cas9 homologous independent targeted integration (HITI). We show that a sequence coding for mCherry can successfully be knocked in at the 5' end of the Arc open reading frame. While nine spCas9 gene editing sites surround the Arc start codon, the accuracy of the editing was highly sequence-dependent, with only a single target resulting in an in-frame reporter integration. When inducing long-term potentiation (LTP) in the hippocampus, we observed an increase of Arc protein highly correlated with an increase in fluorescent intensity and the number of mCherry-positive cells. By proximity ligation assay (PLA), we demonstrated that the mCherry-Arc fusion protein retains the Arc function by interacting with the transmembrane protein stargazin in postsynaptic spines. Finally, we recorded mCherry-Arc interaction with presynaptic protein Bassoon in mCherry-negative surrounding neurons at close proximity to mCherry-positive spines of edited neurons. This is the first study to provide support for inter-neuronal in vivo transfer of Arc in the mammalian brain.