Inhibition of group I metabotropic glutamate receptors reverses autistic-like phenotypes caused by deficiency of the translation repressor eIF4E binding protein 2

Exacerbated mRNA translation during brain development has been linked to autism spectrum disorders (ASDs). Deletion of the eukaryotic initiation factor 4E (eIF4E)-binding protein 2 gene (Eif4ebp2), encoding the suppressor of mRNA translation initiation 4E-BP2, leads to an imbalance in excitatory-to-inhibitory neurotransmission and ASD-like behaviors. Inhibition of group I metabotropic glutamate receptors (mGluRs) mGluR1 and mGluR5 reverses the autistic phenotypes in several ASD mouse models. Importantly, these receptors control synaptic physiology via activation of mRNA translation. We investigated the potential reversal of autistic-like phenotypes in Eif4ebp2(−/−) mice by using antagonists of mGluR1 (JNJ16259685) or mGluR5 (fenobam). Augmented hippocampal mGluR-induced long-term depression (LTD; or chemically induced mGluR-LTD) in Eif4ebp2(−/−) mice was rescued by mGluR1 or mGluR5 antagonists. While rescue by mGluR5 inhibition occurs through the blockade of a protein synthesis-dependent component of LTD, normalization by mGluR1 antagonists requires the activation of protein synthesis. Synaptically induced LTD was deficient in Eif4ebp2(−/−) mice, and this deficit was not rescued by group I mGluR antagonists. Furthermore, a single dose of mGluR1 (0.3 mg/kg) or mGluR5 (3 mg/kg) antagonists in vivo reversed the deficits in social interaction and repetitive behaviors (marble burying) in Eif4ebp2(−/−) mice. Our results demonstrate that Eif4ebp2(−/−) mice serve as a relevant model to test potential therapies for ASD symptoms. In addition, we provide substantive evidence that the inhibition of mGluR1/mGluR5 is an effective treatment for physiological and behavioral alterations caused by exacerbated mRNA translation initiation. SIGNIFICANCE STATEMENT Exacerbated mRNA translation during brain development is associated with several autism spectrum disorders (ASDs). We recently demonstrated that the deletion of a negative regulator of mRNA translation initiation, the eukaryotic initiation factor 4E-binding protein 2, leads to ASD-like behaviors and increased excitatory synaptic activity. Here we demonstrated that autistic behavioral and electrophysiological phenotypes can be treated in adult mice with antagonists of group I metabotropic glutamate receptors (mGluRs), which have been previously used in other ASD models (i.e., fragile X syndrome). These findings support the use of group I mGluR antagonists as a potential therapy that extends to autism models involving exacerbated mRNA translation initiation

Cap-binding protein 4EHP effects translation silencing by microRNAs

Significance miRNAs are important components of gene regulatory networks and affect all aspects of cell biology by controlling the stability and translation efficiency of their target mRNAs. Here, we identified the mRNA cap-binding eIF4E-related protein 4EHP as an effector of miRNA-mediated translation repression. Through screening for protein interactions in cells via the BioID method, we identified 4EHP as a component of the CCR4–NOT/DDX6/4E-T axis. Direct interaction between 4E-T and 4EHP increases the latter’s cap-binding affinity, suggesting that this interaction potentiates its competition with the eIF4F complex for binding to the mRNA 5′ cap. Our findings suggest that 4EHP facilitates the formation of a closed-loop structure between the 3′ UTR of the mRNA and its 5′ cap, which causes repression of mRNA translation.</jats:p

Control of embryonic stem cells self-renewal and differentiation via coordinated splicing and translation of YY2

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Translational control of depression-like behavior via phosphorylation of eukaryotic translation initiation factor 4E

Translation of mRNA into protein has a fundamental role in neurodevelopment, plasticity, and memory formation; however, its contribution in the pathophysiology of depressive disorders is not fully understood. We investigated the involvement of MNK1/2 (MAPK-interacting serine/threonine-protein kinase 1 and 2) and their target, eIF4E (eukaryotic initiation factor 4E), in depression-like behavior in mice. Mice carrying a mutation in eIF4E for the MNK1/2 phosphorylation site (Ser209Ala, Eif4e ki/ki), the Mnk1/2 double knockout mice (Mnk1/2 -/-), or mice treated with the MNK1/2 inhibitor, cercosporamide, displayed anxiety-and depression-like behaviors, impaired serotonin-induced excitatory synaptic activity in the prefrontal cortex, and diminished firing of the dorsal raphe neurons. In Eif4e ki/ki mice, brain IκBα, was decreased, while the NF-κB target, TNFα was elevated. TNFα inhibition in Eif4e ki/ki mice rescued, whereas TNFα administration to wild-type mice mimicked the depression-like behaviors and 5-HT synaptic deficits. We conclude that eIF4E phosphorylation modulates depression-like behavior through regulation of inflammatory responses

Structural studies of Ubiquitin related proteins

Posttranslational attachment of ubiquitin (Ub) or poly-Ub chains marks proteins for various cellular fates and functions, including proteasomal degradation, endocytosis, endosomal sorting, and DNA repair. In general, three enzymes catalyze the ubiquitination reaction: activating enzyme (E1), conjugating enzyme (E2), specificity-determining Ub-protein ligase (E3). This thesis examines three distinct aspects of the ubiquitination of proteins.The recognition of substrates by UBR1 and UBR2 proteins: UBR proteins are E3-ligases that recognize certain N-terminal residues (N-degrons) as signals for protein degradation. For this reason, they are called N-recognins. N-recognition follows a turnover rule known as the N-end rule. Using X-ray crystallography, we determined the structure of the substrate-recognition domain of the UBR1 and UBR2 proteins with a bound ligand. These structures showed that the domain adopts a novel fold stabilized through the binding of three zinc ions and forms a binding pocket for N-degrons. Additionally, biochemical affinity measurements established the molecular principles for the recognition of positively charged N-degrons. The elucidation of the ubr-box structure in complex with a type-1 N-degron pioneered the understanding of N-end rule substrate recognition.Substrate binding and ubiquitination by UBR5 protein: UBR5 is an E3 Ub ligase containing a catalytic HECT domain and a peptide-binding domain. The peptide-binding MLLE domain recruits different regulatory proteins through a 12-residue peptide motif, termed PAM2. Using pull-down and ubiquitination assays, we demonstrated that the HECT domain interacts with the adjacent MLLE domain in a PAM2 dependent manner. This interaction modulates binding and ubiquitination of TopBP1, a substrate of UBR5. These results provided a new view on how different domains in UBR5 proteins work together for efficient substrate recognition and ubiquitination. The recognition of Ub or poly-Ub chains by the UBA domain of Swa2 protein: Ub-associated (UBA) domains are ∼40 amino acid motifs occurring in proteins associated with ubiquitination. Most UBA domains bind to mono-Ub as well as poly-Ub. A structural model of the Swa2p UBA domain in complex with Ub showed that Ub recognition occurs predominantly through an atypical interaction through helix α1 of the UBA. Mutagenesis and surface plasmon resonance revealed a second low-affinity Ub-binding site and preference of Swa2p UBA for poly-Ub binding. These results revealed a potential role of Swa2p UBA domain in binding poly-ubiquitinated proteins in vivo, and the UBA domains as communication elements in the Ub system.This thesis provides a better understanding of the mechanisms that the Ub pathway employs to assure selectivity and processivity at three different levels: substrate recognition by the N-end rule, substrate binding and ubiquitination by an E3 ligase, and the recognition of Ub species by UBA domains.Les modifications post-traductionnelles des protéines par une molécule d'ubiquitine (Ub) ou par des chaînes de poly-Ub déterminent leur destin pour diverses fonctions cellulaires notamment la dégradation à travers le protéosome, l'endocytose, le tri endosomique ainsi que la réparation de l'ADN. De façon générale, trois enzymes catalysent une réaction d'ubiquitination: une enzyme d'activation (Ub-activating enzyme E1), une enzyme de conjugaison (Ub-conjugating enzyme E2), et une enzyme qui détermine la spécificité pour le substrat (specificity-determining Ub-protein ligase E3). Cette thèse porte sur trois aspects distincts impliqués dans le processus d'ubiquitination des protéines:La reconnaissance de substrats par les protéines UBR1 et UBR2: les Ub-recognins (UBR) sont des ligases E3 qui reconnaissent des résidus N-terminaux (N-degrons) comme signaux pour la dégradation des protéines. Cette reconnaissance suit une règle de rotation du nombre d'entités ciblées nommée N-end rule (règle du N-terminus). A l'aide de données de cristallographie aux rayons X, nous avons déterminé la structure du domaine UBR-box impliqué dans la reconnaissance du substrat des protéines UBR1 et UBR2 en complexe avec un N-degron. Ces structures montrent que le domaine UBR-box adopte un nouveau repliement stabilisé par trois ions zinc et qu'il forme une poche pour accueillir les N-degrons. Aussi, des mesures biochimiques d'affinité ont permis d'établir des principes moléculaires pour la reconnaissance des N-degrons qui sont chargés positivement.La fixation du substrat et son ubiquitination par la protéine UBR5: UBR5 est une Ub ligase E3 contenant un domaine catalytique HECT et un domaine de liaison peptidique, MLLE. Le domaine MLLE recrute plusieurs protéines régulatrices grâce à leur motif PAM2 composé de douze résidus. En procédant à des expériences de pull-down et à des essais d'ubiquitination, nous avons démontré que le domaine HECT interagissait avec le domaine MLLE adjacent de manière dépendante du motif PAM2. Cette interaction conduit à des changements conformationnels qui modulent le repliement et l'ubiquitination de TopBP1, un substrat d'UBR5.La reconnaissance d'Ubiquitine et de chaînes poly-Ub par le domaine UBA de la protéine Swa2: les domaines UBA (Ub-associated) sont composés d'environ quarante acides aminés présents dans des protéines associées à l'ubiquitination. Les domaines UBA se lient à des mono-Ub in vitro, mais semblent avoir une affinité supérieure pour les chaînes de poly-Ub. Un modèle structurel du domaine UBA de la protéine Swa2p en complexe avec une Ub montre que la reconnaissance de l'Ub se produit principalement par une interaction atypique grâce à l'hélice α1 du domaine UBA. Des essais de résonance plasmonique de surface combinés à de la mutagenèse ont révélé une faible affinité secondaire pour le site de liaison à l'Ub et une préférence de l'UBA de Swa2p pour la liaison aux poly-Ub. Ces résultats ont révélé un rôle potentiel du domaine UBA de Swa2p pour lier les protéines poly-ubiquitinylées in vivo.À trois niveaux différents, la reconnaissance du substrat par le règle N-fin, fixation du substrat et l'ubiquitination par une ligase E3, et la reconnaissance des espèces de l'ubiquitine par domaines UBA, cette thèse a fournir une meilleure compréhension du mécanisme qui la voie Ub emploie pour assurer la sélectivité et la processivité de garder le bon environnement homéostatique dans la cellule

Los efectos diferenciados por la carga de cuidado durante la crisis de la COVID-19 en mujeres científicas: una reflexión sobre los desafíos y posibles acciones en Colombia: Desigualdades en academia y ciencia durante la COVID-19 en Colombia

During the COVID-19 pandemic, on top of the traditional scientific-academic activities, now with everyone at home, the work was stretched to the care of children or relatives, administrative burdens at homes, new virtual educational challenges, and the mental health management of colleagues, students, and research assistants. Although the SARS-CoV-2 virus does not discriminate based on gender or race in its contagion, several studies have shown that the pandemic disproportionately has intensified the productivity gap for women scientists, academics, and professionals, especially mothers. Before the pandemic, the gender perspective was already a topic little addressed in Colombian science, technology, and innovation policies, so it is more than necessary to discuss the challenges that Colombian women scientists face due to the pandemic in the country. Based on the critical review of the available literature on the difficulties expanded for women scientists due to the pandemic, recommendations are presented for possible actions and multisectoral strategies to minimize the impact of COVID-19 pandemic in historically underrepresented communities in the academy and science in our country. The existing evidence on the differentiated effects of the pandemic should generate reflection on how to support scientific personnel in Colombia, especially mothers and caregivers. Strategies are required to identify interventions during and after the pandemic to respond equitably to unequal impacts between genders in academia and science in Colombia.Durante la pandemia de la COVID-19 a las tradicionales actividades científico-académicas, se sumaron en paralelo el cuidado de los hijos o de los familiares, mayor carga del trabajo doméstico, nuevos retos de educación virtual, incluso manejo de salud mental de colegas, estudiantes y asistentes de investigación. Aunque el virus SARS-CoV-2 no discrimina en género o raza en su contagio, varios estudios demuestran que la pandemia afecta de manera desproporcionada la productividad de la investigación hecha por las mujeres en la academia y ciencia, especialmente a las madres. Antes de la pandemia la perspectiva de género ya era un tema poco abordado en las políticas de ciencia, tecnología e innovación colombianas, por lo que es más que necesario discutir los desafíos que las mujeres científicas colombianas enfrentan como resultado de la pandemia en el país. A partir de la revisión crítica de la literatura disponible sobre los retos ampliados para las mujeres científicas debido a la pandemia, se presentan recomendaciones de posibles acciones y estrategias multisectoriales dirigidas a minimizar el impacto de la COVID-19 en las comunidades históricamente subrepresentadas en la academia y la ciencia en nuestro país. La evidencia ya existente sobre los efectos diferenciados de la pandemia debe generar reflexión sobre cómo apoyar al personal científico en Colombia, en especial a madres y cuidadores. Se requieren estrategias para identificar intervenciones durante y después de la pandemia que estén orientadas a responder equitativamente a los impactos desiguales entre géneros en la academia y la ciencia colombiana

Maternal Immune Activation and the Development of Dopaminergic Neurotransmission of the Offspring: Relevance for Schizophrenia and Other Psychoses

Prenatal infections have been linked to the development of schizophrenia (SCZ) and other neurodevelopmental disorders in the offspring, and work in animal models indicates that this is to occur through the maternal inflammatory response triggered by infection. Several studies in animal models demonstrated that acute inflammatory episodes are sufficient to trigger brain alterations in the adult offspring, especially in the mesolimbic dopamine (DA) system, involved in the pathophysiology of SCZ and other disorders involving psychosis. In the current review, we synthesize the literature on the clinical studies implicating prenatal infectious events in the development of SCZ. Then, we summarize evidence from animal models of maternal immune activation (MIA) and the behavioral and molecular alterations relevant for the function of the DAergic system. Furthermore, we discuss the evidence supporting the involvement of maternal cytokines, such as interleukin 6 (IL-6) and leptin (a hormone with effects on inflammation) in mediating the effects of MIA on the fetal brain, leading to the long-lasting effects on the offspring. In particular, IL-6 has been involved in mediating the effects of MIA animal models in the offspring through actions on the placenta, induction of IL-17a, or triggering the decrease in non-heme iron (hypoferremia). Maternal infection is very likely interacting with additional genetic and environmental risk factors in the development of SCZ; systematically investigating how these interactions produce specific phenotypes is the next step in understanding the etiology of complex psychiatric disorders

Structure of REV-ERBβ Ligand-binding Domain Bound to a Porphyrin Antagonist

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