mRNA Translation Research Articles

β2-integrins control HIF1α activation in human neutrophils.

During inflammation, human neutrophils engage β2-integrins to migrate from the blood circulation to inflammatory sites with high cytokine but low oxygen concentrations. We tested the hypothesis that the inhibition of prolyl hydroxylase domain-containing enzymes (PHDs), cytokines, and β2-integrins cooperates in HIF pathway activation in neutrophils. Using either the PHD inhibitor roxadustat (ROX) (pseudohypoxia) or normobaric hypoxia to stabilize HIF, we observed HIF1α protein accumulation in adherent neutrophils. Several inflammatory mediators did not induce HIF1α protein but provided additive or even synergistic signals (e.g., GM-CSF) under pseudohypoxic and hypoxic conditions. Importantly, and in contrast to adherent neutrophils, HIF1α protein expression was not detected in strictly suspended neutrophils despite PHD enzyme inhibition and the presence of inflammatory mediators. Blocking β2-integrins in adherent and activating β2-integrins in suspension neutrophils established the indispensability of β2-integrins for increasing HIF1α protein. Using GM-CSF as an example, increased HIF1α mRNA transcription via JAK2-STAT3 was necessary but not sufficient for HIF1α protein upregulation. Importantly, we found that β2-integrins led to HIF1α mRNA translation through the phosphorylation of the essential translation initiation factors eIF4E and 4EBP1. Finally, pseudohypoxic and hypoxic conditions inducing HIF1α consistently delayed apoptosis in adherent neutrophils on fibronectin under low serum concentrations. Pharmacological HIF1α inhibition reversed delayed apoptosis, supporting the importance of this pathway for neutrophil survival under conditions mimicking extravascular sites. We describe a novel β2-integrin-controlled mechanism of HIF1α stabilization in human neutrophils. Conceivably, this mechanism restricts HIF1α activation in response to hypoxia and pharmacological PHD enzyme inhibitors to neutrophils migrating toward inflammatory sites.

RBM15 drives the progression of lung adenocarcinoma by regulating N6-methyladenosine-mediated LDHA mRNA stability

Abnormal N6-methyladenosine (m6A) methylation in RNA plays a pivotal role in the pathogenesis of many types of tumors by influencing mRNA metabolism, alternative splicing, translocation, stability and translation. However, the specific regulators and underlying mechanisms of m6A modification in the progression of lung adenocarcinoma are not well understood. In this study, we analyzed the RNA-seq transcriptome data downloaded from The Cancer Genome Atlas (TCGA) database, and identified “m6A writer” RNA binding motif protein 15 (RBM15) expression was significantly elevated in lung adenocarcinoma (LUAD) biopsies, and the higher RBM15 levels were correlated with the poorer overall survival (OS) of LUAD patients. Further study confirmed RBM15 was prominently expressed in LUAD tissues and cell lines. Moreover, silencing RBM15 in PC9 and H1299 cells reduced cell proliferation both in vitro and in vivo, while overexpression of RBM15 in A549 cells promoted cell growth. Mechanistically, lactate dehydrogenase A (LDHA) acted as a downstream target of RBM15. RBM15-mediated m6A modification of LDHA mRNA enhanced its stability to exert an oncogenic role in LUAD. Taken together, our findings suggest that the RBM15/LDHA axis might be a novel and promising therapeutic target for LUAD.

Data-augmented machine learning scoring functions for virtual screening of YTHDF1 m6A reader protein

Machine learning is rapidly advancing the drug discovery process, significantly enhancing speed and efficiency. Innovation in computer-aided drug design is primarily driven by structure- and ligand-based approaches. When the number of known inhibitors for a target is limited, data augmentation strategies are often preferred to enhance model performance. In this study, we developed predictive machine learning models for structure-based drug discovery leveraging multiple traditional machine learning algorithms trained with target and ligand dynamics-aware datasets.To illustrate our approach, we present a composite model that combines classification and regression to predict YTHDF1 inhibitors, utilizing PLEC features. YTHDF1, a key m6A reader protein involved in mRNA translation, is implicated in various cancers, making it a promising therapeutic target. Traditional structure-based virtual screening (SBVS) using generic scoring functions has struggled to identify potent YTHDF1 inhibitors due to the protein's unique binding characteristics. To overcome this, we developed YTHDF1-specific machine learning scoring functions (MLSFs) to enhance SBVS efficacy.We employed various data augmentation techniques to generate a comprehensive dataset, incorporating multiple conformations of ligands and the YTHDF1 protein. We have trained 64 YTHDF1-specific MLSFs using four machine learning algorithms and evaluated them on ten test sets, focusing on their predictive and ranking power. Our results demonstrate that the artificial neural network with protein-ligand extended connectivity fingerprints (ANN-PLEC) outperforms other MLSFs, consistently achieving high area under the precision-recall curve (PR-AUC) of 0.87. This method shows promise for targets with limited quantities of active molecules, providing a viable path forward for drug discovery research. The ANN-PLEC scoring function is made freely available on GitHub for other researchers to access and utilize https://github.com/JuniML/SBVS-YTHDF1/.

Cap-Specific m6Am Methyltransferase PCIF1/CAPAM Regulates mRNA Stability of RAB23 and CNOT6 through the m6A Methyltransferase Activity.

Chemical modifications of cellular RNAs play key roles in gene expression and host defense. The cap-adjacent N6,2'-O-dimethyladenosine (m6Am) is a prevalent modification of vertebrate and viral mRNAs and is catalyzed by the newly discovered N6 methyltransferase PCIF1. However, its role in gene expression remains unclear due to conflicting reports on its effects on mRNA stability and translation. In this study, we investigated the impact of siRNA-mediated transient suppression of PCIF1 on global mRNA expression in HeLa cells. We identified a subset of differentially expressed genes (DEGs) that exhibited minimal overlap with previously reported DEGs. Subsequent validation revealed that PCIF1 positively and negatively regulates RAB23 and CNOT6 expression, respectively, at both the mRNA and protein levels. Mechanistic analyses demonstrated that PCIF1 regulates the stability of these target mRNAs rather than their transcription, and rescue experiments confirmed the requirement of PCIF1's methyltransferase activity for these regulations. Furthermore, MeRIP-qPCR analysis showed that PCIF1 suppression significantly reduced the m6A levels of RAB23 and CNOT6 mRNAs. These findings suggest that PCIF1 regulates the stability of specific mRNAs in opposite ways through m6A modification, providing new insights into the role of m6Am in the regulation of gene expression.

The Translatome Map: RNC-Seq vs. Ribo-Seq for Profiling of HBE, A549, and MCF-7 Cell Lines

Gene expression is a tightly regulated process that involves multiple layers of control, including transcriptional, post-transcriptional, and translational regulation. To gain a comprehensive understanding of gene expression dynamics and its functional implications, it is crucial to compare translatomic, transcriptomic, and proteomic data. The two most common analysis methods, Ribo-seq and RNC-Seq, were used to analyze the translatome of the same sample, whose datasets were downloaded from the TranslatomeDB database. The resulting translatome maps obtained for three cell lines (HBE, A549, and MCF-7) using these two methods were comparatively analyzed. The two methods of translatome analysis were shown to provide comparable results and can be used interchangeably. The obtained mRNA translation patterns were annotated in the transcriptome and proteome context for the same sample, which may become the basis for the reconstruction of the molecular mechanisms of pathological process development in the future.

TRMT1L-catalyzed m2 2G27 on tyrosine tRNA is required for efficient mRNA translation and cell survival under oxidative stress.

tRNA modifications are critical for several aspects of their functions, including decoding, folding, and stability. Using a multifaceted approach encompassing eCLIP-seq and Nanopore tRNA-seq, we show that the human tRNA methyltransferase TRMT1L interacts with component of the Rix1 ribosome biogenesis complex and binds to the 28S rRNA, as well as to a subset of tRNAs. Mechanistically, we demonstrate that TRMT1L is responsible for catalyzing m2 2G solely at position 27 of tRNA-Tyr-GUA. Surprisingly, TRMT1L depletion also impaired the deposition of acp3U and dihydrouridine on tRNA-Tyr-GUA, Cys-GCA, and Ala-CGC. TRMT1L knockout cells have a marked decrease in tRNA-Tyr-GUA levels, coinciding with a reduction in global translation rates and hypersensitivity to oxidative stress. Our results establish TRMT1L as the elusive methyltransferase catalyzing the m2 2G27 modification on tRNA Tyr, resolving a long-standing gap of knowledge and highlighting its potential role in a tRNA modification circuit crucial for translation regulation and stress response.

Loss of NAT10 Reduces the Translation of Kmt5a mRNA Through ac4C Modification in Cardiomyocytes and Induces Heart Failure.

In the past decade, the biological functions of various RNA modifications in mammals have been uncovered. N4-acetylcytidine (ac4C), a highly conserved RNA modification, has been implicated in human diseases. Despite this, the involvement of RNA ac4C modification in cardiac physiology and pathology remains incompletely understood. NAT10 (N-acetyltransferase 10) stands as the sole acetyltransferase known to catalyze RNA ac4C modification. This study aims to explore the role of NAT10 and ac4C modification in cardiac physiology and pathology. Cardiac-specific knockout of NAT10, leading to reduced RNA ac4C modification, during both neonatal and adult stages resulted in severe heart failure. NAT10 deficiency induced cardiomyocyte apoptosis, a crucial step in heart failure pathogenesis, supported by invitro data. Activation of the p53 signaling pathway was closely associated with enhanced apoptosis in NAT10-deficient cardiomyocytes. As ac4C modification on mRNA influences translational efficiency, we employed ribosome footprints coupled with RNA sequencing to explore genome-wide translational efficiency changes caused by NAT10 deficiency. We identified and validated that the translational efficiency of Kmt5a was suppressed in NAT10 knockout hearts due to reduced ac4C modification on its mRNA. This finding was consistent with the observation that Kmt5a protein levels were reduced in heart failure despite unchanged mRNA expression. Knockdown of Kmt5a in cardiomyocytes recapitulated the phenotype of NAT10 deficiency, including increased cardiomyocyte apoptosis and activated p53 signaling. Finally, overexpression of Kmt5a rescued cardiomyocyte apoptosis and p53 activation induced by NAT10 inhibition. Our study highlights the significance of NAT10 in cardiomyocyte physiology, demonstrating that NAT10 loss is sufficient to induce cardiomyocyte apoptosis and heart failure. NAT10 regulates the translational efficiency of Kmt5a, a key mediator, through mRNA ac4C modification during heart failure.

MicroRNA Biogenesis, Gene Regulation Mechanisms, and Availability in Foods.

MicroRNAs (miRNAs) are small, non-coding RNAs that control gene expression by degrading or repressing mRNA translation into proteins. Research recently suggested that food-derived miRNAs are bioavailable and may be absorbed in the gastrointestinal tract (GIT). Since these small RNAs may reach the circulation and organs, possible interactions with host genes will lead to epigenetic effects that alter metabolism. Therefore, from a precision nutrition standpoint, exogenous miRNAs may be essential in modulating health status. This review summarizes the process of miRNA biogenesis, the post-translational mechanisms of gene regulation, and their bioavailability in animal- and plant-derived foods.

M6A-driven NAT10 translation facilitates fatty acid metabolic rewiring to suppress ferroptosis and promote ovarian tumorigenesis through enhancing ACOT7 mRNA acetylation.

RNA epigenetic modifications have been implicated in cancer progression. However, the interplay between distinct RNA modifications and its role in cancer metabolism remain largely unexplored. Our study demonstrates that N-acetyltransferase 10 (NAT10) is notably upregulated in ovarian cancer (OC), correlating with poor patient prognosis. IGF2BP1 enhances the translation of NAT10 mRNA in an m6A-dependent manner in OC cells. NAT10 drives tumorigenesis by mediating N4-acetylcytidine (ac4C) modification of ACOT7 mRNA, thereby augmenting its stability and translation. This NAT10-ACOT7 axis modulates fatty acid metabolism in cancer cells and promotes tumor progression by suppressing ferroptosis. Additionally, our research identifies fludarabine as a small molecule inhibitor targeting NAT10, inhibits the ac4C modification and expression of ACOT7 mRNA. By using cell derived xenograft model and patient derived organoid model, we show that fludarabine effectively suppresses ovarian tumorigenesis. Overall, our study highlights the pivotal role of the NAT10-ACOT7 axis in the malignant cancer progression, underscoring the potential of targeting NAT10-mediated ac4C modification as a viable therapeutic strategy for this disease.

MicroRNAs as Indicators of Alterations in Reaction to Endurance Training

Without a doubt, endurance sports are beneficial for heart health and general fitness; regular physical exercise is thought to be one of the best ways to avoid cardiovascular disease. Gene expression is regulated by tiny molecules known as microRNAs, which are generated subsequent to transcription. Translational repression, mRNA deadenylation, and decapping are all caused by miRNAs when they attach to a certain region at the 3′ UTR of their target mRNAs (40, 41). Along with promoter regions, additional mRNA regions such as the 5′ UTR and coding sequence have also been shown to include miRNA binding sites. While it has been shown that miRNA contact with a promoter region may drive transcription, miRNA binding to the 5′ UTR and coding sections silences the expression of genes. According to preliminary research, miRNAs may serve as helpful indicators of the systemic changes brought on by exercise before they are identified using traditional imaging or laboratory methods. This study focused on four important physiological processes that help the body adapt to various endurance workouts. We found that miR-27, miR-221, miR-210, miR-328, miR-133a, miR-134a, and miR-20a are essential for adaptive response to exercise after conducting a thorough literature search.

RNA m6A methyltransferase activator affects anxiety-related behaviours, monoamines and striatal gene expression in the rat.

Modification of mRNA by methylation is involved in post-transcriptional regulation of gene expression by affecting the splicing, transport, stability and translation of mRNA. Methylation of adenosine at N6 (m6A) is one of the most common and important cellular modification occurring in the mRNA of eukaryotes. Evidence that m6A mRNA methylation is involved in regulation of stress response and that its dysregulation may contribute to the pathogenesis of neuropsychiatric disorders is accumulating. We have examined the acute and subchronic (up to 18 days once per day intraperitoneally) effect of the first METTL3/METTL14 activator compound CHMA1004 (methyl-piperazine-2-carboxylate) at two doses (1 and 5 mg/kg) in male and female rats. CHMA1004 had a locomotor activating and anxiolytic-like profile in open field and elevated zero-maze tests. In female rats sucrose consumption and swimming in Porsolt's test were increased. Nevertheless, CHMA1004 did not exhibit strong psychostimulant-like properties: CHMA1004 had no effect on 50-kHz ultrasonic vocalizations except that it reduced the baseline difference between male and female animals, and acute drug treatment had no effect on extracellular dopamine levels in striatum. Subchronic CHMA1004 altered ex vivo catecholamine levels in several brain regions. RNA sequencing of female rat striata after subchronic CHMA1004 treatment revealed changes in the expression of a number of genes linked to dopamine neuron viability, neurodegeneration, depression, anxiety and stress response. Conclusively, the first-in-class METTL3/METTL14 activator compound CHMA1004 increased locomotor activity and elicited anxiolytic-like effects after systemic administration, demonstrating that pharmacological activation of RNA m6A methylation has potential for neuropsychiatric drug development.

Stick-slip unfolding favors self-association of expanded HTT mRNA

In Huntington’s Disease (HD) and related disorders, expansion of CAG trinucleotide repeats produces a toxic gain of function in affected neurons. Expanded huntingtin (expHTT) mRNA forms aggregates that sequester essential RNA binding proteins, dysregulating mRNA processing and translation. The physical basis of RNA aggregation has been difficult to disentangle owing to the heterogeneous structure of the CAG repeats. Here, we probe the folding and unfolding pathways of expHTT mRNA using single-molecule force spectroscopy. Whereas normal HTT mRNAs unfold reversibly and cooperatively, expHTT mRNAs with 20 or 40 CAG repeats slip and unravel non-cooperatively at low tension. Slippage of CAG base pairs is punctuated by concerted rearrangement of adjacent CCG trinucleotides, trapping partially folded structures that readily base pair with another RNA strand. We suggest that the conformational entropy of the CAG repeats, combined with stable CCG base pairs, creates a stick-slip behavior that explains the aggregation propensity of expHTT mRNA.

A translation regulator that drives spermatogonial stem cell formation.

Spermatogonial stem cells (SSCs) are essential for adult spermatogenesis. Themolecular mechanisms driving SSC generation are poorly understood. Zou et al. reported that the precursor cells that give rise to SSCs-prospermatogonia (ProSG) require the RNA-binding protein, DDX20, in orderto undergo the obligatory proliferative re-activation step that proceeds SSC formation. Literature search. We summarize the authors' discovery that the RNA-binding protein, DDX20, iscritical for driving the proliferative re-activation of ProSG, a key step that proceeds SSC generation in vivo. They provide evidence that DDX20 performs this role through its ability to promote the translation of mRNAs encoding proteins known to be essential for cell-cycle and spermatogonial homeostasis. It remains to be determined whether this role is conserved inhumans. It will also be interesting to elucidate whether other post-transcriptional regulators also have roles in early germ cell development. More broadly, it will be fascinating to determine whether post-transcriptional regulators workin concert with transcriptional regulators to drive germ-cell development.

Exploiting Translation Machinery for Cancer Therapy: Translation Factors as Promising Targets

Eukaryotic protein translation has slowly gained the scientific community’s attention for its advanced and powerful therapeutic potential. However, recent technical developments in studying ribosomes and global translation have revolutionized our understanding of this complex multistep process. These developments have improved and deepened the current knowledge of mRNA translation, sparking excitement and new possibilities in this field. Translation factors are crucial for maintaining protein synthesis homeostasis. Since actively proliferating cancer cells depend on protein synthesis, dysregulated protein translation is central to tumorigenesis. Translation factors and their abnormal expressions directly affect multiple oncogenes and tumor suppressors. Recently, small molecules have been used to target translation factors, resulting in translation inhibition in a gene-specific manner, opening the door for developing translation inhibitors that can lead to novel chemotherapeutic drugs for treating multiple cancer types caused by dysregulated translation machinery. This review comprehensively summarizes the involvement of translation factors in tumor progression and oncogenesis. Also, it sheds light on the evolution of translation factors as novel drug targets for developing future therapeutic drugs for treating cancer.

AtPRMT3-RPS2B promotes ribosome biogenesis and coordinates growth and cold adaptation trade-off

Translation, a fundamental process regulating cellular growth and proliferation, relies on functional ribosomes. As sessile organisms, plants have evolved adaptive strategies to maintain a delicate balance between growth and stress response. But the underlying mechanisms, particularly on the translational level, remain less understood. In this study, we revealed the mechanisms of AtPRMT3-RPS2B in orchestrating ribosome assembly and managing translational regulation. Through a forward genetic screen, we identified PDCD2-D1 as a suppressor gene restoring abnormal development and ribosome biogenesis in atprmt3-2 mutants. Our findings confirmed that PDCD2 interacts with AtPRMT3-RPS2B, and facilitates pre-ribosome transport through nuclear pore complex, finally ensuring normal ribosome translation in the cytoplasm. Additionally, the dysfunction of AtPRMT3-RPS2B was found to enhance freezing tolerance. Moreover, we revealed that AtPRMT3-RPS2B promotes the translation of housekeeping mRNAs while concurrently repressing stress-related mRNAs. In summary, our study sheds light on the regulatory roles of AtPRMT3-RPS2B in ribosome assembly and translational balance, enabling the trade-off between growth and stress.

KLHL21 suppresses gastric tumourigenesis via maintaining STAT3 signalling equilibrium in stomach homoeostasis

ObjectivePrecancerous metaplasia transition to dysplasia poses a risk for subsequent intestinal-type gastric adenocarcinoma. However, the molecular basis underlying the transformation from metaplastic to cancerous cells remains poorly understood.DesignAn integrated analysis...

6589 Antisense Oligonucleotides for Reducing ACTH Secretion in a Model of Cushing's Disease

Abstract Disclosure: M.S. Varughese: None. H. Eltumi: None. E.H. Kemp: None. J.D. Newell-Price: None. Antisense Oligonucleotides for Reducing ACTH Secretion in a Model of Cushing’s Disease Background: Cushing’s disease (CD) is a multi-system disorder with high morbidity and mortality characterised by pathologically raised serum cortisol due excess expression of proopiomelanocortin (Pomc) and overproduction of ACTH by a pituitary corticotroph adenoma. Trans-sphenoidal adenomectomy is the treatment of choice, but there is a 30% recurrence rate over time. Advances in medical therapy are needed. Antisense oligonucleotides (ASOs) can silence mRNA translation by specific base-pairing. Locked nucleic acid (LNA) and 2’-O-methyl (OMe) ribose terminals make ASOs more effective by improving affinity and resistance to nuclease degradation. Aims: To investigate the effectiveness of LNA- and OMe-modified anti-Pomc ASOs at reducing ACTH secretion from murine adrenotropic tumour (AtT20) cells. To analyse the nuclease resistance of Pomc ASOs and their ability to drive an immune response. Methods: Two ASOs (ASO2 and ASO3) were designed against Pomc with phosphorothioate backbones modified with either LNA or OMe ribose terminals. These were used in lipofectamine-mediated cell transfections of AtT20 cells and ACTH in the culture medium measured by immunoassay. ASO stability was assessed by nuclease degradation assays and immunogenicity by cytokine ELISAs. Results: When compared with untreated AtT20 cells, LNA- and OMe-modified Pomc ASOs at 1 nM significantly suppressed ACTH secretion for up to 120 h and 96 h, respectively (n = 4; Unpaired t tests, all P values < 0.05). In contrast, control treatments, including scrambled and mismatched ASOs, did not cause a significant reduction. For comparison, 1 nM of ASO2-OMe, ASO2-LNA, ASO3-OMe and ASO3-LNA lowered ACTH at 24 h by 62%, 71%, 63% and 79%, respectively. Modified Pomc ASOs showed 14-31% degradation over a 120-min incubation period with 3’- and 5’-exonucleases, whilst equivalent unmodified Pomc ASOs were completely degraded. No secretion of IFN-α, IFN-β, TNF-α, IL-6 or IL-1β was detected following transfection of AtT20 cells with Pomc ASOs. Conclusions:Pomc ASOs caused significant reduction of ACTH secretion from AtT-20 cells. LNA-modified Pomc ASOs were more effective than those with OMe modifications, with neither stimulating a detectable immune response. These ASOs hold promise as a systemic therapy for Cushing’s disease. Presentation: 6/3/2024

Targeted Therapy of Osteoarthritis via Intra-Articular Delivery of Lipid-Nanoparticle-Encapsulated Recombinant Human FGF18 mRNA.

Fibroblast growth factor 18 (FGF18) emerges as a promising therapeutic target for osteoarthritis (OA). In this study, a novel articular cavity-localized lipid nanoparticle (LNP) named WG-PL14 is developed. This optimized formulation has a nearly 30-fold increase in mRNA expression as well as better articular cavity enrichment compared to commercial lipids MC3 when performing intra-articular injection. Then, a mRNA sequence encoding recombinant human FGF18 (rhFGF18) for potential mRNA therapy in OA is optimized. In vitro assays confirm the translation of rhFGF18 mRNA into functional proteins within rat and human chondrocytes, promoting cell proliferation and extracellular matrix (ECM) synthesis. Subsequently, the therapeutic efficacy of the LNP-rhFGF18 mRNA complex is systematically assessed in a mouse OA model. The administration exhibits several positive outcomes, including an improved pain response, upregulation of ECM-related genes (e.g., AGRN and HAS2), and remodeling of subchondral bone homeostasis compared to a control group. Taken together, these findings underscore the potential of localized LNP-rhFGF18 mRNA therapy in promoting the regeneration of cartilage tissue and mitigating the progression of OA.

Pathogenic tau induces an adaptive elevation in mRNA translation rate at early stages of disease.

Alterations in the rate and accuracy of messenger RNA (mRNA) translation are associated with aging and several neurodegenerative disorders, including Alzheimer's disease and related tauopathies. We previously reported that error-containing RNA that are normally cleared via nonsense-mediated mRNA decay (NMD), a key RNA surveillance mechanism, are translated in the adult brain of a Drosophila model of tauopathy. In the current study, we find that newly-synthesized peptides and translation machinery accumulate within nuclear envelope invaginations that occur as a consequence of tau pathology, and that the rate of mRNA translation is globally elevated in early stages of disease in adult brains of Drosophila models of tauopathy. Polysome profiling from adult heads of tau transgenic Drosophila reveals the preferential translation of specific mRNA that have been previously linked to neurodegeneration. Unexpectedly, we find that panneuronal elevation of NMD further elevates the global translation rate in tau transgenic Drosophila, as does treatment with rapamycin. As NMD activation and rapamycin both suppress tau-induced neurodegeneration, their shared effect on translation suggests that elevated rates of mRNA translation are an early adaptive mechanism to limit neurodegeneration. Our work provides compelling evidence that tau-induced deficits in NMD reshape the tau translatome by increasing translation of RNA that are normally repressed in healthy cells.

Dysregulating mTORC1-4E-BP2 signaling in GABAergic interneurons impairs hippocampus-dependent learning and memory.

Memory formation is contingent on molecular and structural changes in neurons in response to learning stimuli-a process known as neuronal plasticity. The initiation step of mRNA translation is a gatekeeper of long-term memory by controlling the production of plasticity-related proteins in the brain. The mechanistic target of rapamycin complex 1 (mTORC1) controls mRNA translation, mainly through phosphorylation of the eukaryotic initiation factor 4E (eIF4E)-binding proteins (4E-BPs) and ribosomal protein S6 kinases (S6Ks). mTORC1 signaling decreases throughout brain development, starting from the early postnatal period. Here, we discovered that in mice, the age-dependent decrease in mTORC1 signaling occurs selectively in excitatory but not inhibitory neurons. Using a gene conditional knockout (cKO) strategy, we demonstrate that either up- or downregulating the mTORC1-4E-BP2 axis in GAD65 inhibitory interneurons, but not excitatory neurons, results in long-term object recognition and object location memory deficits. Our data indicate that the mTORC1 pathway in inhibitory but not excitatory neurons plays a key role in memory formation.