RESUMEN
The integrated stress response (ISR), a pivotal protein homeostasis network, plays a critical role in the formation of long-term memory (LTM). The precise mechanism by which the ISR controls LTM is not well understood. Here, we report insights into how the ISR modulates the mnemonic process by using targeted deletion of the activating transcription factor 4 (ATF4), a key downstream effector of the ISR, in various neuronal and non-neuronal cell types. We found that the removal of ATF4 from forebrain excitatory neurons (but not from inhibitory neurons, cholinergic neurons, or astrocytes) enhances LTM formation. Furthermore, the deletion of ATF4 in excitatory neurons lowers the threshold for the induction of long-term potentiation, a cellular model for LTM. Transcriptomic and proteomic analyses revealed that ATF4 deletion in excitatory neurons leads to upregulation of components of oxidative phosphorylation pathways, which are critical for ATP production. Thus, we conclude that ATF4 functions as a memory repressor selectively within excitatory neurons.
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Factor de Transcripción Activador 4 , Memoria a Largo Plazo , Neuronas , Animales , Ratones , Factor de Transcripción Activador 4/metabolismo , Factor de Transcripción Activador 4/genética , Astrocitos/metabolismo , Potenciación a Largo Plazo , Memoria a Largo Plazo/fisiología , Ratones Noqueados , Neuronas/metabolismo , Prosencéfalo/metabolismo , MasculinoRESUMEN
An important tenet of learning and memory is the notion of a molecular switch that promotes the formation of long-term memory1-4. The regulation of proteostasis is a critical and rate-limiting step in the consolidation of new memories5-10. One of the most effective and prevalent ways to enhance memory is by regulating the synthesis of proteins controlled by the translation initiation factor eIF211. Phosphorylation of the α-subunit of eIF2 (p-eIF2α), the central component of the integrated stress response (ISR), impairs long-term memory formation in rodents and birds11-13. By contrast, inhibiting the ISR by mutating the eIF2α phosphorylation site, genetically11 and pharmacologically inhibiting the ISR kinases14-17, or mimicking reduced p-eIF2α with the ISR inhibitor ISRIB11, enhances long-term memory in health and disease18. Here we used molecular genetics to dissect the neuronal circuits by which the ISR gates cognitive processing. We found that learning reduces eIF2α phosphorylation in hippocampal excitatory neurons and a subset of hippocampal inhibitory neurons (those that express somatostatin, but not parvalbumin). Moreover, ablation of p-eIF2α in either excitatory or somatostatin-expressing (but not parvalbumin-expressing) inhibitory neurons increased general mRNA translation, bolstered synaptic plasticity and enhanced long-term memory. Thus, eIF2α-dependent mRNA translation controls memory consolidation via autonomous mechanisms in excitatory and somatostatin-expressing inhibitory neurons.
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Factor 2 Eucariótico de Iniciación/metabolismo , Hipocampo/citología , Consolidación de la Memoria , Neuronas/metabolismo , Somatostatina/metabolismo , Animales , Región CA1 Hipocampal/citología , Región CA1 Hipocampal/fisiología , Factor 2 Eucariótico de Iniciación/deficiencia , Factor 2 Eucariótico de Iniciación/genética , Potenciales Postsinápticos Excitadores , Hipocampo/fisiología , Potenciación a Largo Plazo , Masculino , Memoria a Largo Plazo , Ratones , Ratones Endogámicos C57BL , Inhibición Neural , Plasticidad Neuronal , Parvalbúminas , Fosforilación , Células Piramidales/fisiología , Transmisión SinápticaRESUMEN
Activation of neuronal protein synthesis upon learning is critical for the formation of long-term memory. Here, we report that learning in the contextual fear conditioning paradigm engenders a decrease in eIF2α (eukaryotic translation initiation factor 2) phosphorylation in astrocytes in the hippocampal CA1 region, which promotes protein synthesis. Genetic reduction of eIF2α phosphorylation in hippocampal astrocytes enhanced contextual and spatial memory and lowered the threshold for the induction of long-lasting plasticity by modulating synaptic transmission. Thus, learning-induced dephosphorylation of eIF2α in astrocytes bolsters hippocampal synaptic plasticity and consolidation of long-term memories.
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Astrocitos , Potenciación a Largo Plazo , Potenciación a Largo Plazo/fisiología , Plasticidad Neuronal/genética , Hipocampo/fisiología , Biosíntesis de Proteínas , Región CA1 Hipocampal , Memoria a Largo Plazo/fisiologíaRESUMEN
The mechanistic/mammalian target of rapamycin complex 1 (mTORC1) integrates multiple signals to regulate critical cellular processes such as mRNA translation, lipid biogenesis, and autophagy. Germline and somatic mutations in mTOR and genes upstream of mTORC1, such as PTEN, TSC1/2, AKT3, PIK3CA, and components of GATOR1 and KICSTOR complexes, are associated with various epileptic disorders. Increased mTORC1 activity is linked to the pathophysiology of epilepsy in both humans and animal models, and mTORC1 inhibition suppresses epileptogenesis in humans with tuberous sclerosis and animal models with elevated mTORC1 activity. However, the role of mTORC1-dependent translation and the neuronal cell types mediating the effect of enhanced mTORC1 activity in seizures remain unknown. The eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) and 2 (4E-BP2) are translational repressors downstream of mTORC1. Here we show that the ablation of 4E-BP2, but not 4E-BP1, in mice increases the sensitivity to pentylenetetrazole (PTZ)- and kainic acid (KA)-induced seizures. We demonstrate that the deletion of 4E-BP2 in inhibitory, but not excitatory neurons, causes an increase in the susceptibility to PTZ-induced seizures. Moreover, mice lacking 4E-BP2 in parvalbumin, but not somatostatin or VIP inhibitory neurons exhibit a lowered threshold for seizure induction and reduced number of parvalbumin neurons. A mouse model harboring a human PIK3CA mutation that enhances the activity of the PI3K-AKT pathway (Pik3caH1047R-Pvalb ) selectively in parvalbumin neurons shows susceptibility to PTZ-induced seizures. Our data identify 4E-BP2 as a regulator of epileptogenesis and highlight the central role of increased mTORC1-dependent translation in parvalbumin neurons in the pathophysiology of epilepsy.
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Epilepsia/metabolismo , Factores Eucarióticos de Iniciación/metabolismo , Neuronas/metabolismo , Animales , Fosfatidilinositol 3-Quinasa Clase I/genética , Fosfatidilinositol 3-Quinasa Clase I/metabolismo , Epilepsia/genética , Epilepsia/fisiopatología , Factores Eucarióticos de Iniciación/genética , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Ratones , Ratones Endogámicos C57BL , Inhibición Neural , Neuronas/fisiología , Parvalbúminas/genética , Parvalbúminas/metabolismoRESUMEN
The formation of memory for a novel experience is a critical cognitive capacity. The ability to form novel memories is sensitive to age-related pathologies and disease, to which prolonged metabolic stress is a major contributing factor. Presently, we describe a dopamine-dependent redox modulation pathway within the hippocampus of male mice that promotes memory consolidation. Namely, following novel information acquisition, quinone reductase 2 (QR2) is suppressed by miRNA-182 (miR-182) in the CA1 region of the hippocampus via dopamine D1 receptor (D1R) activation, a process largely facilitated by locus coeruleus activity. This pathway activation reduces ROS generated by QR2 enzymatic activity, a process that alters the intrinsic properties of CA1 interneurons 3 h following learning, in a form of oxidative eustress. Interestingly, novel experience decreases QR2 expression predominately in inhibitory interneurons. Additionally, we find that in aged animals this newly described QR2 pathway is chronically under activated, resulting in miR-182 underexpression and QR2 overexpression. This leads to accumulative oxidative stress, which can be seen in CA1 via increased levels of oxidized, inactivated potassium channel Kv2.1, which undergoes disulfide bridge oligomerization. This newly described interneuron-specific molecular pathway lies alongside the known mRNA translation-dependent processes necessary for long-term memory formation, entrained by dopamine in CA1. It is a process crucial for the distinguishing features of novel memory, and points to a promising new target for memory enhancement in aging and age-dependent diseases.SIGNIFICANCE STATEMENT One way in which evolution dictates which sensory information will stabilize as an internal representation, relies on information novelty. Dopamine is a central neuromodulator involved in this process in the mammalian hippocampus. Here, we describe for the first time a dopamine D1 receptor-dependent quinone reductase 2 pathway in interneurons. This is a targeted redox event necessary to delineate a novel experience to a robust long-term internal representation. Activation of this pathway alone can explain the effect novelty has on "flashbulb" memories, and it can become dysfunctional with age and diseases, such as Alzheimer's disease.
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Región CA1 Hipocampal/fisiología , Dopamina/fisiología , Interneuronas/fisiología , Memoria/fisiología , Quinona Reductasas/fisiología , Transducción de Señal/fisiología , Envejecimiento/fisiología , Envejecimiento/psicología , Animales , Región CA1 Hipocampal/crecimiento & desarrollo , Antagonistas de Dopamina/farmacología , Miedo/psicología , Masculino , Consolidación de la Memoria/fisiología , Memoria a Largo Plazo , Ratones , Ratones Endogámicos C57BL , MicroARNs/biosíntesis , MicroARNs/genética , Estrés Oxidativo , Especies Reactivas de Oxígeno/metabolismo , Reconocimiento en Psicología , Canales de Potasio Shab/metabolismoRESUMEN
Conditioned taste aversion (CTA) is an associative learning paradigm, wherein consumption of an appetitive tastant (e.g., saccharin) is paired to the administration of a malaise-inducing agent, such as intraperitoneal injection of LiCl. Aversive taste learning and retrieval require neuronal activity within the anterior insula (aIC) and the basolateral amygdala (BLA). Here, we labeled neurons of the aIC projecting to the BLA in adult male mice using a retro-AAV construct and assessed their necessity in aversive and appetitive taste learning. By restricting the expression of chemogenetic receptors in aIC-to-BLA neurons, we demonstrate that activity within the aIC-to-BLA projection is necessary for both aversive taste memory acquisition and retrieval, but not for its maintenance, nor its extinction. Moreover, inhibition of the projection did not affect incidental taste learning per se, but effectively suppressed aversive taste memory retrieval when applied either during or before the encoding of the unconditioned stimulus for CTA (i.e., malaise). Remarkably, activation of the projection after novel taste consumption, without experiencing any internal discomfort, was sufficient to form an artificial aversive taste memory, resulting in strong aversive behavior upon retrieval. Our results indicate that aIC-to-BLA projecting neurons are an essential component in the ability of the brain to associate taste sensory stimuli with body states of negative valence and guide the expression of valence-specific behavior upon taste memory retrieval.SIGNIFICANCE STATEMENT In the present study we subjected mice to the conditioned taste aversion paradigm, where animals learn to associate novel taste with malaise (i.e., assign it negative valence). We show that activation of neurons in the anterior insular cortex (aIC) that project into the basolateral amygdala (BLA) in response to conditioned taste aversion is necessary to form a memory for a taste of negative valence. Moreover, artificial activation of this pathway (without any feeling of pain) after the sampling of a taste can also lead to such associative memory. Thus, activation of aIC-to-BLA projecting neurons is necessary and sufficient to form and retrieve aversive taste memory.
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Amígdala del Cerebelo/fisiología , Reacción de Prevención/fisiología , Complejo Nuclear Basolateral/fisiología , Neuronas/fisiología , Gusto/fisiología , Amígdala del Cerebelo/química , Animales , Complejo Nuclear Basolateral/química , Masculino , Ratones , Vías Nerviosas/química , Vías Nerviosas/fisiología , Neuronas/química , Técnicas de Cultivo de Órganos , Distribución AleatoriaRESUMEN
Protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK) is one of four known kinases that respond to cellular stress by deactivating the eukaryotic initiation factor 2 α (eIF2α) or other signal transduction cascades. Recently, both eIF2α and its kinases were found to play a role in normal and pathological brain function. Here, we show that reduction of either the amount or the activity of PERK, specifically in the CA1 region of the hippocampus in young adult male mice, enhances neuronal excitability and improves cognitive function. In addition, this manipulation rescues the age-dependent cellular phenotype of reduced excitability and memory decline. Specifically, the reduction of PERK expression in the CA1 region of the hippocampus of middle-aged male mice using a viral vector rejuvenates hippocampal function and improves hippocampal-dependent learning. These results delineate a mechanism for behavior and neuronal aging and position PERK as a promising therapeutic target for age-dependent brain malfunction.SIGNIFICANCE STATEMENT We found that local reduced protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK) expression or activity in the hippocampus enhances neuronal excitability and cognitive function in young normal mice, that old CA1 pyramidal cells have reduced excitability and increased PERK expression that can be rescued by reducing PERK expression in the hippocampus, and that reducing PERK expression in the hippocampus of middle-aged mice enhances hippocampal-dependent learning and memory and restores it to normal performance levels of young mice. These findings uncover an entirely new biological link among PERK, neuronal intrinsic properties, aging, and cognitive function. Moreover, our findings propose a new way to fight mild cognitive impairment and aging-related cognitive deterioration.
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Envejecimiento/fisiología , Cognición/fisiología , Hipocampo/enzimología , Hipocampo/metabolismo , Memoria/fisiología , eIF-2 Quinasa/metabolismo , Adenina/análogos & derivados , Adenina/farmacología , Animales , Cognición/efectos de los fármacos , Disfunción Cognitiva/enzimología , Inhibidores Enzimáticos/farmacología , Indoles/farmacología , Aprendizaje/efectos de los fármacos , Aprendizaje/fisiología , Masculino , Memoria/efectos de los fármacos , Ratones , Células Piramidales/efectos de los fármacos , Células Piramidales/enzimologíaRESUMEN
Learning of novel information, including novel taste, requires activation of neuromodulatory transmission mediated, for example, by the muscarinic acetylcholine receptors (mAChRs) in relevant brain structures. In addition, drugs enhancing the function of mAChRs are used to treat memory impairment and decline. However, the mechanisms underlying these effects are poorly understood. Here, using quantitative RT-PCR in Wistar Hola rats, we found quinone reductase 2 (QR2) to be expressed in the cortex in an mAChR-dependent manner. QR2 mRNA expression in the insular cortex is inversely correlated with mAChR activation both endogenously, after novel taste learning, and exogenously, after pharmacological manipulation of the muscarinic transmission. Moreover, reducing QR2 expression levels through lentiviral shRNA vectors or activity via inhibitors is sufficient to enhance long-term memories. We also show here that, in patients with Alzheimer's disease, QR2 is overexpressed in the cortex. It is suggested that QR2 expression in the cortex is a removable limiting factor of memory formation and thus serves as a new target to enhance cognitive function and delay the onset of neurodegenerative diseases. SIGNIFICANCE STATEMENT: We found that: (1) quinone reductase 2 (QR2) expression is a muscarinic-receptor-dependent removable constraint on memory formation in the cortex, (2) reducing QR2 expression or activity in the cortex enhances memory formation, and (3) Alzheimer's disease patients overexpressed QR2. We believe that these results propose a new mechanism by which muscarinic acetylcholine receptors affect cognition and suggest that inhibition of QR2 is a way to enhance cognition in normal and pathological conditions.
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Corteza Cerebral/enzimología , Regulación Enzimológica de la Expresión Génica , Memoria a Largo Plazo/fisiología , Quinona Reductasas/biosíntesis , Receptores Muscarínicos/metabolismo , Enfermedad de Alzheimer/enzimología , Enfermedad de Alzheimer/patología , Animales , Corteza Cerebral/patología , Humanos , Masculino , Quinona Reductasas/genética , Ratas , Ratas WistarRESUMEN
Protein translation initiation is controlled by levels of eIF2α phosphorylation (p-eIF2α) on Ser51. In addition, increased p-eIF2α levels impair long-term synaptic plasticity and memory consolidation, whereas decreased levels enhance them. Levels of p-eIF2α are determined by four kinases, of which protein kinase RNA-activated (PKR), PKR-like endoplastic reticulum kinase (PERK), and general control nonderepressible 2 are extensively expressed in the mammalian mature brain. Following identification of PERK as the major kinase to determine basal levels of p-eIF2α in primary neuronal cultures, we tested its function as a physiological constraint of memory consolidation in the cortex, the brain structure suggested to store, at least in part, long-term memories in the mammalian brain. To that aim, insular cortex (IC)-dependent positive and negative forms of taste learning were used. Genetic reduction of PERK expression was accomplished by local microinfusion of a lentivirus harboring PERK Short hairpin RNA, and pharmacological inhibition was achieved by local microinfusion of a PERK-specific inhibitor (GSK2606414) to the rat IC. Both genetic reduction of PERK expression and pharmacological inhibition of its activity reduced p-eIF2α levels and enhanced novel taste learning and conditioned taste aversion, but not memory retrieval. Moreover, enhanced extinction was observed together with enhanced associative memory, suggesting increased cortical-dependent behavioral plasticity. The results suggest that, by phosphorylating eIF2α, PERK functions in the cortex as a physiological constraint of memory consolidation, and its downregulation serves as cognitive enhancement.
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Corteza Cerebral/fisiología , Aprendizaje/fisiología , Gusto/fisiología , eIF-2 Quinasa/metabolismo , Adenina/análogos & derivados , Adenina/farmacología , Animales , Reacción de Prevención/efectos de los fármacos , Reacción de Prevención/fisiología , Corteza Cerebral/efectos de los fármacos , Factor 2 Eucariótico de Iniciación/metabolismo , Indoles/farmacología , Aprendizaje/efectos de los fármacos , Ratones , Fosforilación , ARN Interferente Pequeño , Ratas , Gusto/efectos de los fármacos , eIF-2 Quinasa/antagonistas & inhibidores , eIF-2 Quinasa/genéticaRESUMEN
Whole chicken breast was injected with potassium bicarbonate (PB), sodium bicarbonate (SB), and potassium lactate (K-lactate) and salt, alone or in combination at different concentration levels. The objectives were to 1) investigate the effects of different concentration of PB, SB, and PL on instrumental color, water-holding capacity (WHC), objective tenderness, expressible moisture, and moisture content and 2) evaluate whether sodium-containing ingredients can be replaced with potassium as a potential strategy to reduce total sodium content in the finished product. Results showed that chicken breast tissue marinated with SB and PB had greater moisture retention, display characteristics, and cooked product qualities than chicken breast tissue injected with water and the nonmarinated control. The L* values (lightness) did not change over the period of retail display and were not different compared to the control (P>0.05). The chicken breast enhanced with SB, PB, and K-lactate retained better retail display color than the controls (marinated with water and nonmarinated). Increasing the potassium bicarbonate concentration from 0.5 to 1.5% significantly improved the water-holding capacity (82.17 to 92.61%; P<0.05) and led to better cook yield (83.84 to 91.96%). Shear force values were lower at the 0.5% level for both SB and PB compared to the control. PB performed better on retail display and cooked meat quality than SB. This study suggests that chicken breast tissue can be marinated with KB as a healthier alternative to phosphate or SB.
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Bicarbonatos/química , Ácido Láctico/química , Carne/normas , Animales , Pollos , Conservación de Alimentos/métodosRESUMEN
Background: Obesity is a burgeoning global health problem with an escalating prevalence and severe implications for public health. New evidence indicates that long non-coding RNAs (lncRNAs) may play a pivotal role in regulating adipose tissue function and energy homeostasis across various species. However, the molecular mechanisms underlying obesity remain elusive. Scope of review: This review discusses obesity and fat metabolism in general, highlighting the emerging importance of lncRNAs in modulating adipogenesis. It describes the regulatory networks, latest tools, techniques, and approaches to enhance our understanding of obesity and its lncRNA-mediated epigenetic regulation in humans and Drosophila. Major conclusions: This review analyses large datasets of human and Drosophila lncRNAs from published databases and literature with experimental evidence supporting lncRNAs role in fat metabolism. It concludes that lncRNAs play a crucial role in obesity-related metabolism. Cross-species comparisons highlight the relevance of Drosophila findings to human obesity, emphasizing their potential role in adipose tissue biology. Furthermore, it discusses how recent technological advancements and multi-omics data integration enhance our capacity to characterize lncRNAs and their function. Additionally, this review briefly touches upon innovative methodologies like experimental evolution and advanced sequencing technologies for identifying novel genes and lncRNA regulators in Drosophila, which can potentially contribute to obesity research.
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Memory consolidation is defined temporally based on pharmacological interventions such as inhibitors of mRNA translation (molecular consolidation) or post-acquisition deactivation of specific brain regions (systems level consolidation). However, the relationship between molecular and systems consolidation are poorly understood. Molecular consolidation mechanisms involved in translation initiation and elongation have previously been studied in the cortex using taste-learning paradigms. For example, the levels of phosphorylation of eukaryotic elongation factor 2 (eEF2) were found to be correlated with taste learning in the gustatory cortex (GC), minutes following learning. In order to isolate the role of the eEF2 phosphorylation state at Thr-56 in both molecular and system consolidation, we analyzed cortical-dependent taste learning in eEF2K (the only known kinase for eEF2) ki mice, which exhibit reduced levels of eEF2 phosphorylation but normal levels of eEF2 and eEF2K. These mice exhibit clear attenuation of cortical-dependent associative, but not of incidental, taste learning. In order to gain a better understanding of the underlying mechanisms, we compared brain activity as measured by MEMRI (manganese-enhanced magnetic resonance imaging) between eEF2K ki mice and WT mice during conditioned taste aversion (CTA) learning and observed clear differences between the two but saw no differences under basal conditions. Our results demonstrate that adequate levels of phosphorylation of eEF2 are essential for cortical-dependent associative learning and suggest that malfunction of memory processing at the systems level underlies this associative memory impairment.
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Aprendizaje por Asociación/fisiología , Conducta Animal/fisiología , Química Encefálica/genética , Quinasa del Factor 2 de Elongación/deficiencia , Quinasa del Factor 2 de Elongación/genética , Percepción del Gusto/genética , Animales , Química Encefálica/fisiología , Condicionamiento Psicológico/fisiología , Quinasa del Factor 2 de Elongación/metabolismo , Imagen por Resonancia Magnética/métodos , Manganeso , Memoria/fisiología , Ratones , Fosforilación/genética , Percepción del Gusto/fisiologíaRESUMEN
Imported mangoes have been linked to outbreaks of salmonellosis in the USA. The purpose of this research was to evaluate the persistence and growth kinetics of Salmonella and Listeria monocytogenes on the intact surface of whole 'Ataulfo', 'Kent', and 'Tommy Atkins' mangoes stored at three different temperatures. L. monocytogenes was also evaluated on fresh-cut 'Tommy Atkins' mangoes stored at 4, 12, 20 ± 2°C. Whole mangoes were spot inoculated with rifampicin-resistant pathogen cocktails (6 log CFU/mango) onto the midsection of whole fruit (n = 6). Fruit was stored at 12, 20, or 30 ± 2°C and sampled for up to 28 days. The specific growth rates derived from DMFit models as a function of time were used to develop secondary models. On 'Kent' mangoes, Salmonella had a population increase from 0.3 to 1.1 log CFU/mango with a linear growth rate of â¼0.004, 0.01, and 0.06 log CFU/mango/h at 12, 20, and 30°C, respectively. At 20 and 30°C, Salmonella growth rates were significantly higher than 12°C (P < 0.05). No clear Salmonella growth trend was observed; populations decreased up to 1.6 log CFU/mango on 'Tommy Atkins' and 'Ataulfo' at 12°C. Populations of L. monocytogenes on whole and fresh-cut mangoes declined regardless of temperature and storage period. Food safety during storage should be the top priority for fresh-cut tropical fruit processors.
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Listeria monocytogenes , Mangifera , Microbiología de Alimentos , Recuento de Colonia Microbiana , Salmonella , Temperatura , Manipulación de AlimentosRESUMEN
Repeated or prolonged, but not short-term, general anesthesia during the early postnatal period causes long-lasting impairments in memory formation in various species. The mechanisms underlying long-lasting impairment in cognitive function are poorly understood. Here, we show that repeated general anesthesia in postnatal mice induces preferential apoptosis and subsequent loss of parvalbumin-positive inhibitory interneurons in the hippocampus. Each parvalbumin interneuron controls the activity of multiple pyramidal excitatory neurons, thereby regulating neuronal circuits and memory consolidation. Preventing the loss of parvalbumin neurons by deleting a proapoptotic protein, mitochondrial anchored protein ligase (MAPL), selectively in parvalbumin neurons rescued anesthesia-induced deficits in pyramidal cell inhibition and hippocampus-dependent long-term memory. Conversely, partial depletion of parvalbumin neurons in neonates was sufficient to engender long-lasting memory impairment. Thus, loss of parvalbumin interneurons in postnatal mice following repeated general anesthesia critically contributes to memory deficits in adulthood.
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Anestesia , Parvalbúminas , Ratones , Animales , Parvalbúminas/genética , Parvalbúminas/metabolismo , Interneuronas/metabolismo , Neuronas/metabolismo , Células Piramidales/metabolismo , Hipocampo/metabolismo , Trastornos de la Memoria/inducido químicamente , Trastornos de la Memoria/genética , Trastornos de la Memoria/metabolismoRESUMEN
Dysregulation of protein synthesis is one of the key mechanisms underlying autism spectrum disorder (ASD). However, the role of a major pathway controlling protein synthesis, the integrated stress response (ISR), in ASD remains poorly understood. Here, we demonstrate that the main arm of the ISR, eIF2α phosphorylation (p-eIF2α), is suppressed in excitatory, but not inhibitory, neurons in a mouse model of fragile X syndrome (FXS; Fmr1-/y). We further show that the decrease in p-eIF2α is mediated via activation of mTORC1. Genetic reduction of p-eIF2α only in excitatory neurons is sufficient to increase general protein synthesis and cause autism-like behavior. In Fmr1-/y mice, restoration of p-eIF2α solely in excitatory neurons reverses elevated protein synthesis and rescues autism-related phenotypes. Thus, we reveal a previously unknown causal relationship between excitatory neuron-specific translational control via the ISR pathway, general protein synthesis, and core phenotypes reminiscent of autism in a mouse model of FXS.
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Trastorno del Espectro Autista , Trastorno Autístico , Síndrome del Cromosoma X Frágil , Animales , Ratones , Síndrome del Cromosoma X Frágil/genética , Síndrome del Cromosoma X Frágil/metabolismo , Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil/genética , Neuronas/metabolismo , Fenotipo , Ratones Noqueados , Modelos Animales de EnfermedadRESUMEN
Biological aging can be described as accumulative, prolonged metabolic stress and is the major risk factor for cognitive decline and Alzheimer's disease (AD). Recently, we identified and described a quinone reductase 2 (QR2) pathway in the brain, in which QR2 acts as a removable memory constraint and metabolic buffer within neurons. QR2 becomes overexpressed with age, and it is possibly a novel contributing factor to age-related metabolic stress and cognitive deficit. We found that, in human cells, genetic removal of QR2 produced a shift in the proteome opposing that found in AD brains while simultaneously reducing oxidative stress. We therefore created highly specific QR2 inhibitors (QR2is) to enable evaluation of chronic QR2 inhibition as a means to reduce biological age-related metabolic stress and cognitive decline. QR2is replicated results obtained by genetic removal of QR2, while local QR2i microinjection improved hippocampal and cortical-dependent learning in rats and mice. Continuous consumption of QR2is in drinking water improved cognition and reduced pathology in the brains of AD-model mice (5xFAD), with a noticeable between-sex effect on treatment duration. These results demonstrate the importance of QR2 activity and pathway function in the healthy and neurodegenerative brain and what we believe to be the great therapeutic potential of QR2is as first-in-class drugs.
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Enfermedad de Alzheimer , Quinona Reductasas , Animales , Humanos , Ratones , Ratas , Enfermedad de Alzheimer/tratamiento farmacológico , Enfermedad de Alzheimer/genética , Hipocampo/metabolismo , Estrés Oxidativo , Quinona Reductasas/antagonistas & inhibidores , Quinona Reductasas/genética , Quinona Reductasas/metabolismo , Estrés FisiológicoRESUMEN
Poultry litter is applied to crop production land in the southern United States as a waste management strategy as it is a nitrogen-rich fertilizer and plentiful throughout the region. While litter is a known reservoir for human enteric pathogens including Salmonella enterica, little is known regarding pathogen prevalence, concentration, and common serotypes within the material. Litter from thirteen farms across four southern states was examined for Salmonella. Samples (n = 490) from six of the thirteen (46.2%) farms tested positive. Thirty-three samples out of 490 (6.7%) were Salmonella positive. Salmonella was ca. 95% less likely to be collected from stacked litter piles than from the poultry house floor or pasture, and every day increase in litter age reduced the likelihood of recovering Salmonella by 5.1%. When present, concentrations of Salmonella in contaminated poultry litter were variable, ranging from <0.45 to >280,000 MPN/g. The most prevalent serotypes found were Kentucky (45.5%), Kiambu (18.2%), and Michigan (12.1%). Salmonella Kentucky also had the greatest distribution and was found on 4 of the 6 (66.7%) positive farms. Results from this survey demonstrated that Salmonella prevalence and concentration in poultry litter is highly variable, and good agricultural practices are critical to safely use poultry litter as a soil amendment on fresh produce fields.
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Aves de Corral , Salmonella enterica , Animales , Pollos , Humanos , Prevalencia , Serogrupo , Suelo , Estados Unidos/epidemiologíaRESUMEN
Recent studies have demonstrated that selective activation of mammalian target of rapamycin complex 1 (mTORC1) in the cerebellum by deletion of the mTORC1 upstream repressors TSC1 or phosphatase and tensin homolog (PTEN) in Purkinje cells (PCs) causes autism-like features and cognitive deficits. However, the molecular mechanisms by which overactivated mTORC1 in the cerebellum engenders these behaviors remain unknown. The eukaryotic translation initiation factor 4E-binding protein 2 (4E-BP2) is a central translational repressor downstream of mTORC1. Here, we show that mice with selective ablation of 4E-BP2 in PCs display a reduced number of PCs, increased regularity of PC action potential firing, and deficits in motor learning. Surprisingly, although spatial memory is impaired in these mice, they exhibit normal social interaction and show no deficits in repetitive behavior. Our data suggest that, downstream of mTORC1/4E-BP2, there are distinct cerebellar mechanisms independently controlling social behavior and memory formation.
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Trastorno Autístico/genética , Proteínas Portadoras/metabolismo , Factores Eucarióticos de Iniciación/metabolismo , Biosíntesis de Proteínas/genética , Células de Purkinje/metabolismo , Memoria Espacial/fisiología , Animales , Humanos , RatonesRESUMEN
The trace fear conditioning protocol is designed to measure hippocampal function in mice. The protocol includes a neutral conditioned stimulus (tone) and an aversive unconditioned stimulus (shock), separated in time by a trace interval. The trace interval between the tone and the shock critically involves the hippocampus and could be used to evaluate hippocampal-dependent learning and memory. In this protocol, we presented mice with five pairings of tone and shock separated by a 20 sec trace interval. Freezing was measured 24 h after conditioning to evaluate contextual memory by placing mice in the conditioned chamber. In addition, 48 h after conditioning, freezing was measured in a dark chamber, which served as a different context. This method enables precise detection of hippocampal-dependent learning and memory following pharmacological and genetic manipulations that impair or enhance hippocampal function.
RESUMEN
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.