RÉSUMÉ
In the search for the origin of Amyotrophic Lateral Sclerosis disease (ALS), we hypothesized earlier (Monselise, 2019) that D-amino acids produced by stressed microbiome may serve as inducers of the disease development. Many examples of D-amino acid accumulation under various stress conditions were demonstrated in prokaryotic and eukaryotic cells. In this work, wild-type Escherichia coli, members of the digestive system, were subjected to carbon and nitrogen starvation stress. Using NMR and LC-MS techniques, we found for the first time that D-glutamate accumulated in the stressed bacteria but not in control cells. These results together with the existing knowledge, allow us to suggest a new insight into the pathway of ALS development: D-glutamate, produced by the stressed microbiome, induces neurobiochemical miscommunication setting on C1q of the complement system. Proving this insight may have great importance in preventive medicine of such MND modern-age diseases as ALS, Alzheimer, and Parkinson.
Sujet(s)
Sclérose latérale amyotrophique , Escherichia coli , Acide glutamique , Sclérose latérale amyotrophique/métabolisme , Sclérose latérale amyotrophique/microbiologie , Escherichia coli/métabolisme , Acide glutamique/métabolisme , Humains , Stress physiologique , Complément C1q/métabolisme , Azote/métabolisme , Carbone/métabolismeRÉSUMÉ
BACKGROUND: Epilepsy is a widespread central nervous system disorder with an estimated 50 million people affected globally. It is characterized by a bimodal incidence peak among infants and the elderly and is influenced by a variety of risk factors, including a significant genetic component. Despite the use of anti-epileptic drugs (AEDs), drug-refractory epilepsy develops in about one-third of patients, highlighting the need for alternative therapeutic approaches. AIMS: The primary aim of this study was to evaluate the neuroprotective effects of troglitazone (TGZ) in epilepsy and to explore the potential mechanisms underlying its action. METHODS: We employed both in vitro and in vivo models to assess TGZ's effects. The in vitro model involved glutamate-induced toxicity in HT22 mouse hippocampal neurons, while the in vivo model used kainic acid (KA) to induce epilepsy in mice. A range of methods, including Hoechst/PI staining, CCK-8 assay, flow cytometry, RT-PCR analysis, Nissl staining, scanning electron microscopy, and RNA sequencing, were utilized to assess various parameters such as cellular damage, viability, lipid-ROS levels, mitochondrial membrane potential, mRNA expression, seizure grade, and mitochondrial morphology. RESULTS: Our results indicate that TGZ, at doses of 5 or 20 mg/kg/day, significantly reduces KA-induced seizures and neuronal damage in mice by inhibiting the process of ferroptosis. Furthermore, TGZ was found to prevent changes in mitochondrial morphology. In the glutamate-induced HT22 cell damage model, 2.5 µM TGZ effectively suppressed neuronal ferroptosis, as shown by a reduction in lipid-ROS accumulation, a decrease in mitochondrial membrane potential, and an increase in PTGS2 expression. The anti-ferroptotic effect of TGZ was confirmed in an erastin-induced HT22 cell damage model as well. Additionally, TGZ reversed the upregulation of Plaur expression in HT22 cells treated with glutamate or erastin. The downregulation of Plaur expression was found to alleviate seizures and reduce neuronal damage in the mouse hippocampus. CONCLUSION: This study demonstrates that troglitazone has significant therapeutic potential in the treatment of epilepsy by reducing epileptic seizures and the associated brain damage through the inhibition of neuronal ferroptosis. The downregulation of Plaur expression plays a crucial role in TGZ's anti-ferroptotic effect, offering a promising avenue for the development of new epilepsy treatments.
Sujet(s)
Épilepsie , Ferroptose , Neuroprotecteurs , Troglitazone , Animaux , Souris , Épilepsie/traitement médicamenteux , Épilepsie/induit chimiquement , Ferroptose/effets des médicaments et des substances chimiques , Ferroptose/physiologie , Neuroprotecteurs/pharmacologie , Neurones/effets des médicaments et des substances chimiques , Neurones/métabolisme , Hippocampe/effets des médicaments et des substances chimiques , Hippocampe/anatomopathologie , Hippocampe/métabolisme , Acide glutamique/métabolisme , Mâle , Acide kaïnique/toxicité , Souris de lignée C57BL , Potentiel de membrane mitochondriale/effets des médicaments et des substances chimiques , Anticonvulsivants/pharmacologie , Anticonvulsivants/usage thérapeutiqueRÉSUMÉ
Human hyaluronidase 1 (HYAL1) and PH20 play vital roles in degrading hyaluronic acids through the substrate-assisted double displacement mechanism. While HYAL1, a lysosomal enzyme, functions optimally under acidic conditions, PH20, a sperm surface hyaluronidase, displays a broader pH range, from acidic to neutral. Our objective was to extend HYAL1's pH range towards neutral pH by introducing repulsive charge-charge interactions involving the catalytic Glu131, increasing its pKa as the proton donor. Substituting individual acidic residues in the ß3-loop (S77D), ß3'-ß3â³ hairpin (T86D and P87E), and at Ala132 (A132D and A132E) enabled HYAL1 to demonstrate enzyme activity at pH 7, with the mutants S77D, P87E, and A132E showing the highest activity in the substrate gel assay. However, double and triple substitutions, including S77D/T86D/A132E as found in the PH20 configuration, did not result in enhanced activity compared to single substitutions. Conversely, PH20 mutants with non-acidic substitutions, such as D94S in the ß3-loop and D103T in the ß3'-ß3â³ hairpin, significantly reduced activity within the pH range of 4 to 7. However, the PH20 mutant E149A, reciprocally substituted compared to A132E in HYAL1, exhibited activity similar to PH20 wild-type (WT) at pH 7. In a turbidimetric assay, HYAL1 mutants with single acidic substitutions exhibited activity similar to that of PH20 WT at pH 7. These results suggest that substituting acidic residues near Glu131 results in HYAL1 activity at neutral pH through electrostatic repulsion. This study highlights the significance of charge-charge interactions in both HYAL1 and PH20 in regulating the pH-dependent activity of hyaluronidases.
Sujet(s)
Hyaluronoglucosaminidase , Humains , Substitution d'acide aminé , Domaine catalytique , Molécules d'adhérence cellulaire , Acide glutamique/métabolisme , Acide glutamique/composition chimique , Acide hyaluronique/métabolisme , Acide hyaluronique/composition chimique , Hyaluronoglucosaminidase/composition chimique , Hyaluronoglucosaminidase/métabolisme , Hyaluronoglucosaminidase/génétique , Concentration en ions d'hydrogène , Modèles moléculaires , MutationRÉSUMÉ
Glutamate is involved in fundamental functions, including neuronal plasticity and memory. Astrocytes are integral elements involved in synaptic function, and the GLT-1 transporter possesses a critical role in glutamate uptake. Here, we study the role of GLT-1, specifically located in astrocytes, in the consolidation, expression, reconsolidation and persistence of spatial object recognition memory in rats. Administration of dihydrokainic acid (DHK), a selective GLT-1 inhibitor, into the dorsal hippocampus around a weak training which only induces short-term memory, promotes long-term memory formation. This promotion is prevented by hippocampal administration of protein-synthesis translation inhibitor, blockade of Activity-regulated cytoskeleton-associated protein (Arc) translation or Brain-Derived Neurotrophic Factor (BDNF) action, which are plasticity related proteins necessary for memory consolidation. However, DHK around a strong training, which induces long-term memory, does not affect memory consolidation. Administration of DHK before the test session impairs the expression of long-term memory, and this effect is dependent of Arc translation. Furthermore, DHK impairs reconsolidation if applied before a reactivation session, and this effect is independent of Arc translation. These findings reveal specific consequences on spatial memory stages developed under hippocampal GLT-1 blockade, shedding light on the intricate molecular mechanisms, governed in part for the action of glia.
Sujet(s)
Astrocytes , Facteur neurotrophique dérivé du cerveau , Protéines du cytosquelette , Acide glutamique , Hippocampe , Mémoire spatiale , Animaux , Hippocampe/effets des médicaments et des substances chimiques , Hippocampe/métabolisme , Hippocampe/physiologie , Astrocytes/effets des médicaments et des substances chimiques , Astrocytes/métabolisme , Mémoire spatiale/effets des médicaments et des substances chimiques , Facteur neurotrophique dérivé du cerveau/métabolisme , Mâle , Rats , Protéines du cytosquelette/métabolisme , Protéines du cytosquelette/génétique , Acide glutamique/métabolisme , Protéines de tissu nerveux/métabolisme , Protéines de tissu nerveux/antagonistes et inhibiteurs , Protéines de tissu nerveux/génétique , Transporteur-2 d'acides aminés excitateurs/métabolisme , Transporteur-2 d'acides aminés excitateurs/antagonistes et inhibiteurs , Rat Wistar , Acide kaïnique/pharmacologie , Acide kaïnique/analogues et dérivés , Consolidation de la mémoire/effets des médicaments et des substances chimiquesRÉSUMÉ
The neuronal excitotoxicity that follows reoxygenation after a hypoxic period may contribute to epilepsy, Alzheimer's disease, Parkinson's disease and various disorders that are related to inadequate supplement of oxygen in neurons. Therefore, counteracting the deleterious effects of post-hypoxic stress is an interesting strategy to treat a large spectrum of neurodegenerative diseases. Here, we show that the expression of the key telomere protecting protein Trf2 decreases in the brain of mice submitted to a post-hypoxic stress. Moreover, downregulating the expression of Terf2 in hippocampal neural cells of unchallenged mice triggers an excitotoxicity-like phenotype including glutamate overexpression and behavioral alterations while overexpressing Terf2 in hippocampal neural cells of mice subjected to a post-hypoxic treatment prevents brain damages. Moreover, Terf2 overexpression in culture neurons counteracts the oxidative stress triggered by glutamate. Finally, we provide evidence that the effect of Terf2 downregulation on excitotoxicity involves Sirt3 repression leading to mitochondrial dysfunction. We propose that increasing the level of Terf2 expression is a potential strategy to reduce post-hypoxic stress damages.
Sujet(s)
Neurones , Sirtuine-3 , Protéine-2 de liaison aux répétitions télomériques , Animaux , Souris , Protéine-2 de liaison aux répétitions télomériques/métabolisme , Protéine-2 de liaison aux répétitions télomériques/génétique , Sirtuine-3/métabolisme , Sirtuine-3/génétique , Neurones/métabolisme , Neurones/anatomopathologie , Hippocampe/métabolisme , Hippocampe/anatomopathologie , Stress oxydatif , Mitochondries/métabolisme , Encéphale/métabolisme , Encéphale/anatomopathologie , Hypoxie/métabolisme , Acide glutamique/métabolisme , Télomère/métabolisme , Télomère/génétique , MâleRÉSUMÉ
Isoliensinine (ISO), a natural compound, is a bibenzyl isoquinoline alkaloid monomer in lotus seed, which has strong antioxidant and free radical scavenging activities. The oxidative toxicity caused by glutamic acid overdose is one of the important mechanisms of nerve cell injury, and the oxidative toxicity caused by glutamic acid is related to ferroptosis. This study aims to establish a glutamate-induced injury model of mouse hippocampal neurons HT-22 cells, and investigate the protective effect of ISO on the neurotoxicity of glutamate-induced HT-22 cells. The results showed that ISO inhibited glutamate-induced ferroptosis of neuronal cells through nuclear factor E2-related factor 2/glutathione peroxidase 4 (Nrf2/GPX4) signaling pathway. Pretreatment of HT-22 cells with ISO significantly reduced glutamate-induced cell death. Ferroptosis inhibitors have the same effect. ISO inhibited the decrease of mitochondrial membrane potential detection and the increase of iron content induced by glutamate, the increase of malondialdehyde and reactive oxygen species in cytoplasm and lipid, and protected the activities of GPx and superoxide dismutase enzymes. In addition, WB showed that glutamic acid could induce the upregulated expression of long-chain esteryl coA synthase 4 (ACSL4) protein and the downregulated expression of SLC7A11 and GPX4 protein in HT-22 cells, while ISO could prevent the abnormal expression of these proteins induced by glutamic acid. The nuclear translocation of Nrf2 in HT-22 cells was increased, and the expression of downstream heme oxygenase-1 protein was upregulated. In summary, ISO protects HT-22 cells from glutamate-induced ferroptosis through a novel mechanism of the Nrf2/GPX4 signaling pathway.
Sujet(s)
Ferroptose , Acide glutamique , Facteur-2 apparenté à NF-E2 , Phospholipid hydroperoxide glutathione peroxidase , Transduction du signal , Animaux , Ferroptose/effets des médicaments et des substances chimiques , Souris , Acide glutamique/toxicité , Acide glutamique/métabolisme , Phospholipid hydroperoxide glutathione peroxidase/métabolisme , Facteur-2 apparenté à NF-E2/métabolisme , Transduction du signal/effets des médicaments et des substances chimiques , Lignée cellulaire , Isoquinoléines/pharmacologie , Neurones/effets des médicaments et des substances chimiques , Neurones/métabolismeRÉSUMÉ
The evolutionary transition from diffusion-mediated cell-cell communication to faster, targeted synaptic signaling in animal nervous systems is still unclear. Genome sequencing analyses have revealed a widespread distribution of synapse-related genes among early-diverging metazoans, but how synaptic machinery evolved remains largely unknown. Here, we examine the function of neurexins (Nrxns), a family of presynaptic cell adhesion molecules with critical roles in bilaterian chemical synapses, using the cnidarian model, Nematostella vectensis. Delta-Nrxns are expressed mainly in neuronal cell clusters that exhibit both peptidergic and classical neurotransmitter signaling. Knockdown of δ-Nrxn reduces spontaneous peristalsis of N. vectensis polyps. Interestingly, gene knockdown and pharmacological studies suggest that δ-Nrxn is involved in glutamate- and glycine-mediated signaling rather than peptidergic signaling. Knockdown of the epithelial α-Nrxn reveals a major role in cell adhesion between ectodermal and endodermal epithelia. Overall, this study provides molecular, functional, and cellular insights into the pre-neural function of Nrxns, as well as key information for understanding how and why they were recruited to the synaptic machinery.
Sujet(s)
, Neurones , Anémones de mer , Animaux , Adhérence cellulaire/génétique , Techniques de knock-down de gènes , Acide glutamique/métabolisme , Glycine/métabolisme , Molécules d'adhérence cellulaire neurales/métabolisme , Molécules d'adhérence cellulaire neurales/génétique , Neurones/métabolisme , Anémones de mer/génétique , Anémones de mer/métabolisme , Transduction du signal , Synapses/métabolisme , /métabolismeRÉSUMÉ
Cognitive impairment affects 29-67% of patients with neuromyelitis optica spectrum disorder. Previous studies have reported glutamate homeostasis disruptions in astrocytes, leading to imbalances in gamma-aminobutyric acid levels. However, the association between these neurotransmitter changes and cognitive deficits remains inadequately elucidated. Point RESolved Spectroscopy and Hadamard Encoding and Reconstruction of MEGA-Edited Spectroscopy techniques were utilized to evaluate gamma-aminobutyric acid, glutamate, glutathione levels, and excitation/inhibition balance in the anterior cingulate cortex, posterior cingulate cortex, and occipital cortex of 39 neuromyelitis optica spectrum disorder patients and 41 healthy controls. Cognitive function was assessed using neurocognitive scales. Results showed decreased gamma-aminobutyric acid levels alongside increased glutamate, glutathione, and excitation/inhibition ratio in the anterior cingulate cortex and posterior cingulate cortex of neuromyelitis optica spectrum disorder patients. Specifically, within the posterior cingulate cortex of neuromyelitis optica spectrum disorder patients, decreased gamma-aminobutyric acid levels and increased excitation/inhibition ratio correlated significantly with anxiety scores, whereas glutathione levels predicted diminished executive function. The results suggest that neuromyelitis optica spectrum disorder patients exhibit dysregulation in the GABAergic and glutamatergic systems in their brains, where the excitation/inhibition imbalance potentially acts as a neuronal metabolic factor contributing to emotional disorders. Additionally, glutathione levels in the posterior cingulate cortex region may serve as predictors of cognitive decline, highlighting the potential benefits of reducing oxidative stress to safeguard cognitive function in neuromyelitis optica spectrum disorder patients.
Sujet(s)
Acide glutamique , Gyrus du cingulum , Spectroscopie par résonance magnétique , Neuromyélite optique , Acide gamma-amino-butyrique , Humains , Gyrus du cingulum/métabolisme , Gyrus du cingulum/imagerie diagnostique , Femelle , Adulte , Neuromyélite optique/métabolisme , Neuromyélite optique/imagerie diagnostique , Mâle , Acide glutamique/métabolisme , Spectroscopie par résonance magnétique/méthodes , Adulte d'âge moyen , Acide gamma-amino-butyrique/métabolisme , Glutathion/métabolisme , Jeune adulte , Agents neuromédiateurs/métabolisme , Dysfonctionnement cognitif/métabolisme , Dysfonctionnement cognitif/imagerie diagnostiqueRÉSUMÉ
Clinical studies have reported that increased epileptiform and subclinical epileptiform activity can be detected in many patients with an Alzheimer's disease (AD) diagnosis using electroencephalogram (EEG) and this may correlate with poorer cognition. Ascorbate may have a specific role as a neuromodulator in AD as it is released concomitantly with glutamate reuptake following excitatory neurotransmission. Insufficiency may therefore result in an exacerbated excitatory/inhibitory imbalance in neuronal signaling. Using a mouse model of AD that requires dietary ascorbate (Gulo-/-APPswe/PSEN1dE9), EEG was recorded at baseline and during 4 weeks of ascorbate depletion in young (5-month-old) and aged (20-month-old) animals. Data were scored for changes in quantity of spike trains, individual spikes, sleep-wake rhythms, sleep fragmentation, and brainwave power bands during light periods each week. We found an early increase in neuronal spike discharges with age and following ascorbate depletion in AD model mice and not controls, which did not correlate with brain amyloid load. Our data also show more sleep fragmentation with age and with ascorbate depletion. Additionally, changes in brain wave activity were observed within different vigilance states in both young and aged mice, where Gulo-/-APPswe/PSEN1dE9 mice had shifts towards higher frequency bands (alpha, beta, and gamma) and ascorbate depletion resulted in shifts towards lower frequency bands (delta and theta). Microarray data supported ascorbate insufficiency altering glutamatergic transmission through the decreased expression of glutamate related genes, however no changes in protein expression of glutamate reuptake transporters were observed. These data suggest that maintaining optimal brain ascorbate levels may support normal brain electrical activity and sleep patterns, particularly in AD patient populations where disruptions are observed.
Sujet(s)
Maladie d'Alzheimer , Carence en acide ascorbique , Acide ascorbique , Modèles animaux de maladie humaine , Électroencéphalographie , Acide glutamique , Souris transgéniques , Animaux , Maladie d'Alzheimer/métabolisme , Maladie d'Alzheimer/physiopathologie , Maladie d'Alzheimer/génétique , Acide ascorbique/métabolisme , Acide glutamique/métabolisme , Souris , Carence en acide ascorbique/métabolisme , Carence en acide ascorbique/physiopathologie , Encéphale/métabolisme , Encéphale/physiopathologie , Transduction du signal/physiologie , Mâle , PhénotypeRÉSUMÉ
Glutamate is traditionally viewed as the first messenger to activate NMDAR (N-methyl-D-aspartate receptor)-dependent cell death pathways in stroke1,2, but unsuccessful clinical trials with NMDAR antagonists implicate the engagement of other mechanisms3-7. Here we show that glutamate and its structural analogues, including NMDAR antagonist L-AP5 (also known as APV), robustly potentiate currents mediated by acid-sensing ion channels (ASICs) associated with acidosis-induced neurotoxicity in stroke4. Glutamate increases the affinity of ASICs for protons and their open probability, aggravating ischaemic neurotoxicity in both in vitro and in vivo models. Site-directed mutagenesis, structure-based modelling and functional assays reveal a bona fide glutamate-binding cavity in the extracellular domain of ASIC1a. Computational drug screening identified a small molecule, LK-2, that binds to this cavity and abolishes glutamate-dependent potentiation of ASIC currents but spares NMDARs. LK-2 reduces the infarct volume and improves sensorimotor recovery in a mouse model of ischaemic stroke, reminiscent of that seen in mice with Asic1a knockout or knockout of other cation channels4-7. We conclude that glutamate functions as a positive allosteric modulator for ASICs to exacerbate neurotoxicity, and preferential targeting of the glutamate-binding site on ASICs over that on NMDARs may be strategized for developing stroke therapeutics lacking the psychotic side effects of NMDAR antagonists.
Sujet(s)
Canaux ioniques sensibles à l'acidité , Encéphalopathie ischémique , Acide glutamique , Animaux , Femelle , Humains , Mâle , Souris , Amino-2 phosphono-5 valérate/effets indésirables , Amino-2 phosphono-5 valérate/métabolisme , Amino-2 phosphono-5 valérate/pharmacologie , Canaux ioniques sensibles à l'acidité/composition chimique , Canaux ioniques sensibles à l'acidité/déficit , Canaux ioniques sensibles à l'acidité/effets des médicaments et des substances chimiques , Canaux ioniques sensibles à l'acidité/génétique , Canaux ioniques sensibles à l'acidité/métabolisme , Régulation allostérique/effets des médicaments et des substances chimiques , Sites de fixation/génétique , Encéphalopathie ischémique/induit chimiquement , Encéphalopathie ischémique/traitement médicamenteux , Encéphalopathie ischémique/métabolisme , Encéphalopathie ischémique/anatomopathologie , Modèles animaux de maladie humaine , Évaluation préclinique de médicament , Acide glutamique/analogues et dérivés , Acide glutamique/métabolisme , Acide glutamique/pharmacologie , Acide glutamique/toxicité , Souris knockout , Mutagenèse dirigée , Protons , Récepteurs du N-méthyl-D-aspartate/antagonistes et inhibiteurs , Récepteurs du N-méthyl-D-aspartate/composition chimique , Récepteurs du N-méthyl-D-aspartate/métabolismeRÉSUMÉ
The Polycomb Repressive Complex 2 (PRC2) regulates corticogenesis, yet the consequences of mutations to this epigenetic modifier in the mature brain are poorly defined. Importantly, PRC2 core genes are haploinsufficient and causative of several human neurodevelopmental disorders. To address the role of PRC2 in mature cortical structure and function, we conditionally deleted the PRC2 gene Eed from the developing mouse dorsal telencephalon. Adult homozygotes displayed smaller forebrain structures. Single-nucleus transcriptomics revealed that glutamatergic neurons were particularly affected, exhibiting dysregulated gene expression profiles, accompanied by aberrations in neuronal morphology and connectivity. Remarkably, homozygous mice performed well on challenging cognitive tasks. In contrast, while heterozygous mice did not exhibit clear anatomical or behavioral differences, they displayed dysregulation of neuronal genes and altered neuronal morphology that was strikingly different from homozygous phenotypes. Collectively, these data reveal how alterations to PRC2 function shape the mature brain and reveal a dose-specific role for PRC2 in determining glutamatergic neuron identity.
Sujet(s)
Acide glutamique , Neurogenèse , Neurones , Complexe répresseur Polycomb-2 , Animaux , Complexe répresseur Polycomb-2/génétique , Complexe répresseur Polycomb-2/métabolisme , Neurones/métabolisme , Neurones/physiologie , Souris , Neurogenèse/physiologie , Acide glutamique/métabolisme , Cortex cérébral/croissance et développement , Cortex cérébral/métabolisme , Cortex cérébral/cytologie , Mâle , Souris de lignée C57BL , Femelle , Souris transgéniquesRÉSUMÉ
BACKGROUND: Metabolism is increasingly recognized as a key regulator of the function and phenotype of the primary cellular constituents of the atherosclerotic vascular wall, including endothelial cells, smooth muscle cells, and inflammatory cells. However, a comprehensive analysis of metabolic changes associated with the transition of plaque from a stable to a hemorrhaged phenotype is lacking. METHODS: In this study, we integrated two large mRNA expression and protein abundance datasets (BIKE, n = 126; MaasHPS, n = 43) from human atherosclerotic carotid artery plaque to reconstruct a genome-scale metabolic network (GEM). Next, the GEM findings were linked to metabolomics data from MaasHPS, providing a comprehensive overview of metabolic changes in human plaque. RESULTS: Our study identified significant changes in lipid, cholesterol, and inositol metabolism, along with altered lysosomal lytic activity and increased inflammatory activity, in unstable plaques with intraplaque hemorrhage (IPH+) compared to non-hemorrhaged (IPH-) plaques. Moreover, topological analysis of this network model revealed that the conversion of glutamine to glutamate and their flux between the cytoplasm and mitochondria were notably compromised in hemorrhaged plaques, with a significant reduction in overall glutamate levels in IPH+ plaques. Additionally, reduced glutamate availability was associated with an increased presence of macrophages and a pro-inflammatory phenotype in IPH+ plaques, suggesting an inflammation-prone microenvironment. CONCLUSIONS: This study is the first to establish a robust and comprehensive GEM for atherosclerotic plaque, providing a valuable resource for understanding plaque metabolism. The utility of this GEM was illustrated by its ability to reliably predict dysregulation in the cholesterol hydroxylation, inositol metabolism, and the glutamine/glutamate pathway in rupture-prone hemorrhaged plaques, a finding that may pave the way to new diagnostic or therapeutic measures.
Sujet(s)
Artériopathies carotidiennes , Acide glutamique , Glutamine , Macrophages , Voies et réseaux métaboliques , Phénotype , Plaque d'athérosclérose , Humains , Glutamine/métabolisme , Acide glutamique/métabolisme , Macrophages/métabolisme , Macrophages/anatomopathologie , Artériopathies carotidiennes/métabolisme , Artériopathies carotidiennes/anatomopathologie , Artériopathies carotidiennes/génétique , Rupture spontanée , Artères carotides/anatomopathologie , Artères carotides/métabolisme , Métabolomique , Bases de données génétiques , Inflammation/métabolisme , Inflammation/génétique , Inflammation/anatomopathologie , Métabolisme énergétique , Jeux de données comme sujet , MâleRÉSUMÉ
Beta-N-methylamino-l-alanine (BMAA) is a potential neurotoxic nonprotein amino acid, which can reach the human body through the food chain. When BMAA interacts with bicarbonate in the human body, carbamate adducts are produced, which share a high structural similarity with the neurotransmitter glutamate. It is believed that BMAA and its l-carbamate adducts bind in the glutamate binding site of ionotropic glutamate receptor 2 (GluR2). Chronic exposure to BMAA and its adducts could cause neurological illness such as neurodegenerative diseases. However, the mechanism of BMAA action and its carbamate adducts bound to GluR2 has not yet been elucidated. Here, we investigate the binding modes and the affinity of BMAA and its carbamate adducts to GluR2 in comparison to the natural agonist, glutamate, to understand whether these can act as GluR2 modulators. Initially, we perform molecular dynamics simulations of BMAA and its carbamate adducts bound to GluR2 to examine the stability of the ligands in the S1/S2 ligand-binding core of the receptor. In addition, we utilize alchemical free energy calculations to compute the difference in the free energy of binding of the beta-carbamate adduct of BMAA to GluR2 compared to that of glutamate. Our findings indicate that carbamate adducts of BMAA and glutamate remain stable in the binding site of the GluR2 compared to BMAA. Additionally, alchemical free energy results reveal that glutamate and the beta-carbamate adduct of BMAA have comparable binding affinity to the GluR2. These results provide a rationale that BMAA carbamate adducts may be, in fact, the modulators of GluR2 and not BMAA itself.
Sujet(s)
Acides aminés diaminés , Carbamates , Toxines de cyanobactéries , Récepteur de l'AMPA , Récepteur de l'AMPA/métabolisme , Récepteur de l'AMPA/composition chimique , Acides aminés diaminés/composition chimique , Acides aminés diaminés/métabolisme , Carbamates/composition chimique , Carbamates/métabolisme , Simulation de dynamique moléculaire , Humains , Sites de fixation , Liaison aux protéines , Acide glutamique/métabolisme , Acide glutamique/composition chimique , LigandsRÉSUMÉ
Sporulation as a typical bacterial differentiation process has been studied for decades. However, two crucial aspects of sporulation, (i) the energy sources supporting the process, and (ii) the maintenance of spore dormancy throughout sporulation, are scarcely explored. Here, we reported the crucial role of RocG-mediated glutamate catabolism in regulating mother cell lysis, a critical step for sporulation completion of Bacillus subtilis, likely by providing energy metabolite ATP. Notably, rocG overexpression resulted in an excessive ATP accumulation in sporulating cells, leading to adverse effects on future spore properties, e.g. increased germination efficiency, reduced DPA content, and lowered heat resistance. Additionally, we revealed that Ald-mediated alanine metabolism was highly related to the inhibition of premature germination and the maintenance of spore dormancy during sporulation, which might be achieved by decreasing the typical germinant L-alanine concentration in sporulating environment. Our data inferred that sporulation of B. subtilis was a highly orchestrated biological process requiring a delicate balance in diverse metabolic pathways, hence ensuring both the completion of sporulation and production of high-quality spores.
Sujet(s)
Adénosine triphosphate , Alanine , Bacillus subtilis , Protéines bactériennes , Acide glutamique , Spores bactériens , Bacillus subtilis/métabolisme , Bacillus subtilis/croissance et développement , Bacillus subtilis/physiologie , Spores bactériens/croissance et développement , Spores bactériens/métabolisme , Acide glutamique/métabolisme , Alanine/métabolisme , Protéines bactériennes/métabolisme , Protéines bactériennes/génétique , Adénosine triphosphate/métabolisme , Régulation de l'expression des gènes bactériens , Voies et réseaux métaboliquesRÉSUMÉ
The hypothalamic ventral premammillary nucleus (PMv) is a glutamatergic nucleus essential for the metabolic control of reproduction. However, conditional deletion of leptin receptor long form (LepRb) in vesicular glutamate transporter 2 (Vglut2) expressing neurons results in virtually no reproductive deficits. In this study, we determined the role of glutamatergic neurotransmission from leptin responsive PMv neurons on puberty and fertility. We first assessed if stimulation of PMv neurons induces luteinizing hormone (LH) release in fed adult females. We used the stimulatory form of designer receptor exclusively activated by designer drugs (DREADDs) in LeprCre (LepRb-Cre) mice. We collected blood sequentially before and for 1 hr after intravenous clozapine-N-oxide injection. LH level increased in animals correctly targeted to the PMv, and LH level was correlated to the number of Fos immunoreactive neurons in the PMv. Next, females with deletion of Slc17a6 (Vglut2) in LepRb neurons (LeprΔVGlut2) showed delayed age of puberty, disrupted estrous cycles, increased gonadotropin-releasing hormone (GnRH) concentration in the axon terminals, and disrupted LH secretion, suggesting impaired GnRH release. To assess if glutamate is required for PMv actions in pubertal development, we generated a Cre-induced reexpression of endogenous LepRb (LeprloxTB) with concomitant deletion of Slc17a6 (Vglut2flox) mice. Rescue of Lepr and deletion of Slc17a6 in the PMv was obtained by stereotaxic injection of an adeno-associated virus vector expressing Cre recombinase. Control LeprloxTB mice with PMv LepRb rescue showed vaginal opening, follicle maturation, and became pregnant, while LeprloxTB;Vglut2flox mice showed no pubertal development. Our results indicate that glutamatergic neurotransmission from leptin sensitive neurons regulates the reproductive axis, and that leptin action on pubertal development via PMv neurons requires Vglut2.
Sujet(s)
Acide glutamique , Récepteurs à la leptine , Maturation sexuelle , Transmission synaptique , Animaux , Femelle , Récepteurs à la leptine/métabolisme , Récepteurs à la leptine/génétique , Souris , Acide glutamique/métabolisme , Neurones/métabolisme , Neurones/physiologie , Reproduction , Transporteur vésiculaire-2 du glutamate/métabolisme , Transporteur vésiculaire-2 du glutamate/génétique , Hormone lutéinisante/sang , Hormone lutéinisante/métabolismeRÉSUMÉ
There has been a significant increase in the consumption of cannabis for both recreational and medicinal purposes in recent years, and its use can have long-term consequences on cognitive functions, including memory. Here, we review the immediate and long-term effects of cannabis and its derivatives on glutamatergic neurotransmission, with a focus on both the presynaptic and postsynaptic alterations. Several factors can influence cannabinoid-mediated changes in glutamatergic neurotransmission, including dosage, sex, age, and frequency of use. Acute exposure to cannabis typically inhibits glutamate release, whereas chronic use tends to increase glutamate release. Conversely, the postsynaptic alterations are more complicated than the presynaptic effects, as cannabis can affect the glutamate receptor expression and the downstream signaling of glutamate. All these effects ultimately influence cognitive functions, particularly memory. This review will cover the current research on glutamate-cannabis interactions, as well as the future directions of research needed to understand cannabis-related health effects and neurological and psychological aspects of cannabis use.
Sujet(s)
Cannabinoïdes , Cannabis , Acide glutamique , Transmission synaptique , Humains , Transmission synaptique/effets des médicaments et des substances chimiques , Cannabinoïdes/pharmacologie , Cannabinoïdes/métabolisme , Acide glutamique/métabolisme , Cannabis/métabolisme , AnimauxRÉSUMÉ
In a recent publication in Cell, Woo et al.1 report that stimulator of interferon genes (STING) links inflammation with glutamate-driven excitotoxicity to induce ferroptosis, identifying a mechanism of inflammation-induced neurodegeneration and also a novel candidate therapeutic target for multiple sclerosis.
Sujet(s)
Ferroptose , Protéines membranaires , Sclérose en plaques , Neuroprotection , Humains , Protéines membranaires/métabolisme , Protéines membranaires/génétique , Animaux , Sclérose en plaques/génétique , Sclérose en plaques/immunologie , Sclérose en plaques/traitement médicamenteux , Sclérose en plaques/métabolisme , Ferroptose/effets des médicaments et des substances chimiques , Ferroptose/génétique , Molécule-1 d'interaction stromale/métabolisme , Molécule-1 d'interaction stromale/génétique , Acide glutamique/métabolisme , Inflammation , Transduction du signalRÉSUMÉ
Cholinergic striatal interneurons (ChIs) express the vesicular glutamate transporter 3 (VGLUT3) which allows them to regulate the striatal network with glutamate and acetylcholine (ACh). In addition, VGLUT3-dependent glutamate increases ACh vesicular stores through vesicular synergy. A missense polymorphism, VGLUT3-p.T8I, was identified in patients with substance use disorders (SUDs) and eating disorders (EDs). A mouse line was generated to understand the neurochemical and behavioral impact of the p.T8I variant. In VGLUT3T8I/T8I male mice, glutamate signaling was unchanged but vesicular synergy and ACh release were blunted. Mutant male mice exhibited a reduced DA release in the dorsomedial striatum but not in the dorsolateral striatum, facilitating habit formation and exacerbating maladaptive use of drug or food. Increasing ACh tone with donepezil reversed the self-starvation phenotype observed in VGLUT3T8I/T8I male mice. Our study suggests that unbalanced dopaminergic transmission in the dorsal striatum could be a common mechanism between SUDs and EDs.
Sujet(s)
Corps strié , Dopamine , Animaux , Mâle , Dopamine/métabolisme , Souris , Corps strié/métabolisme , Humains , Acétylcholine/métabolisme , Troubles liés à une substance/métabolisme , Troubles liés à une substance/génétique , Transduction du signal/effets des médicaments et des substances chimiques , Acide glutamique/métabolisme , Interneurones/métabolisme , Interneurones/effets des médicaments et des substances chimiques , Troubles de l'alimentation/métabolisme , Troubles de l'alimentation/génétique , Troubles de l'alimentation/physiopathologie , Souris de lignée C57BL , Systèmes de transport d'acides aminés acides/métabolisme , Systèmes de transport d'acides aminés acides/génétique , Mutation , Mutation faux-sens , Transporteurs vésiculaires de l'acétylcholineRÉSUMÉ
In the central nervous system of vertebrates, glutamate serves as the primary excitatory neurotransmitter. However, in the retina, glutamate released from photoreceptors causes hyperpolarization in post-synaptic ON-bipolar cells through a glutamate-gated chloride current, which seems paradoxical. Our research reveals that this current is modulated by two excitatory glutamate transporters, EAAT5b and EAAT7. In the zebrafish retina, these transporters are located at the dendritic tips of ON-bipolar cells and interact with all four types of cone photoreceptors. The absence of these transporters leads to a decrease in ON-bipolar cell responses, with eaat5b mutants being less severely affected than eaat5b/eaat7 double mutants, which also exhibit altered response kinetics. Biophysical investigations establish that EAAT7 is an active glutamate transporter with a predominant anion conductance. Our study is the first to demonstrate the direct involvement of post-synaptic glutamate transporters in inhibitory direct synaptic transmission at a central nervous system synapse.
Sujet(s)
Système X-AG de transport d'acides aminés , Rétine , Transmission synaptique , Protéines de poisson-zèbre , Danio zébré , Animaux , Danio zébré/métabolisme , Rétine/métabolisme , Système X-AG de transport d'acides aminés/métabolisme , Système X-AG de transport d'acides aminés/génétique , Protéines de poisson-zèbre/métabolisme , Protéines de poisson-zèbre/génétique , Acide glutamique/métabolisme , Mutation , Cellules bipolaires rétiniennes/métabolismeRÉSUMÉ
Tobacco smoking is the main etiological factor of lung cancer (LC), which can also cause metabolome disruption. This study aimed to investigate whether the observed metabolic shift in LC patients was also associated with their smoking status. Untargeted metabolomics profiling was applied for the initial screening of changes in serum metabolic profile between LC and chronic obstructive pulmonary disease (COPD) patients, selected as a non-cancer group. Differences in metabolite profiles between current and former smokers were also tested. Then, targeted metabolomics methods were applied to verify and validate the proposed LC biomarkers. For untargeted metabolomics, a single extraction-dual separation workflow was applied. The samples were analyzed using a liquid chromatograph-high resolution quadrupole time-of-flight mass spectrometer. Next, the selected metabolites were quantified using liquid chromatography-triple-quadrupole mass spectrometry. The acquired data confirmed that patients' stratification based on smoking status impacted the discriminating ability of the identified LC marker candidates. Analyzing a validation set of samples enabled us to determine if the putative LC markers were truly robust. It demonstrated significant differences in the case of four metabolites: allantoin, glutamic acid, succinic acid, and sphingosine-1-phosphate. Our research showed that studying the influence of strong environmental factors, such as tobacco smoking, should be considered in cancer marker research since it reduces the risk of false positives and improves understanding of the metabolite shifts in cancer patients.