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Background: Mainly known as a transcription factor patterning the rostral brain and governing its histogenesis, FOXG1 has been also detected outside the nucleus; however, biological meaning of that has been only partially clarified. Results: Prompted by FOXG1 expression in cytoplasm of pallial neurons, we investigated its implication in translational control. We documented the impact of FOXG1 on ribosomal recruitment of Grin1-mRNA, encoding for the main subunit of NMDA receptor. Next, we showed that FOXG1 increases GRIN1 protein level by enhancing the translation of its mRNA, while not increasing its stability. Molecular mechanisms underlying this activity included FOXG1 interaction with EIF4E and, possibly, Grin1-mRNA. Besides, we found that, within murine neocortical cultures, de novo synthesis of GRIN1 undergoes a prominent and reversible, homeostatic regulation and FOXG1 is instrumental to that. Finally, by integrated analysis of multiple omic data, we inferred that FOXG1 is implicated in translational control of hundreds of neuronal genes, modulating ribosome engagement and progression. In a few selected cases, we experimentally verified such inference. Conclusions: These findings point to FOXG1 as a key effector, potentially crucial to multi-scale temporal tuning of neocortical pyramid activity, an issue with profound physiological and neuropathological implications. [ABSTRACT FROM AUTHOR]

Abstract Background Mainly known as a transcription factor patterning the rostral brain and governing its histogenesis, FOXG1 has been also detected outside the nucleus; however, biological meaning of that has been only partially clarified. Results Prompted by FOXG1 expression in cytoplasm of pallial neurons, we investigated its implication in translational control. We documented the impact of FOXG1 on ribosomal recruitment of Grin1-mRNA, encoding for the main subunit of NMDA receptor. Next, we showed that FOXG1 increases GRIN1 protein level by enhancing the translation of its mRNA, while not increasing its stability. Molecular mechanisms underlying this activity included FOXG1 interaction with EIF4E and, possibly, Grin1-mRNA. Besides, we found that, within murine neocortical cultures, de novo synthesis of GRIN1 undergoes a prominent and reversible, homeostatic regulation and FOXG1 is instrumental to that. Finally, by integrated analysis of multiple omic data, we inferred that FOXG1 is implicated in translational control of hundreds of neuronal genes, modulating ribosome engagement and progression. In a few selected cases, we experimentally verified such inference. Conclusions These findings point to FOXG1 as a key effector, potentially crucial to multi-scale temporal tuning of neocortical pyramid activity, an issue with profound physiological and neuropathological implications.

The GRIN1, ASCL3, and NOS1 genes are associated with various phenotypes of neuropsychiatric disorders. For instance, these genes contribute to the development of schizophrenia, Alzheimer’s and Parkinson’s diseases, and epilepsy. These genes are also associated with various cancers. For example, ASCL3 is overexpressed in breast cancer, and NOS1, in ovarian cancer cell lines. Based on our findings and literature data, we had previously obtained results suggesting that the single-nucleotide polymorphisms (SNPs) that disrupt erythropoiesis are highly likely to be associated with cognitive and neuropsychiatric disorders in humans. In the present work, using SNP_TATA_Z-tester, we investigated the influence of unannotated SNPs in the TATA boxes of the promoters of the GRIN1, ASCL3, and NOS1 genes (which are involved in neuropsychiatric disorders and cancers) on the interaction of the TATA boxes with the TATA-binding protein (TBP). Double-stranded oligodeoxyribonucleotides identical to the TATA-containing promoter regions of the GRIN1, ASCL3, and NOS1 genes (reference and minor alleles) and recombinant human TBP were employed to study in vitro (by an electrophoretic mobility shift assay) kinetic characteristics of the formation of TBP–TATA complexes and their affinity. It was found, for example, that allele A of rs1402667001 in the GRIN1 promoter increases TBP–TATA affinity 1.4-fold, whereas allele C in the TATA box of the ASCL3 promoter decreases the affinity 1.4-fold. The lifetime of the complexes in both cases decreased by ~20 % due to changes in the rates of association and dissociation of the complexes (ka and kd, respectively). Our experimental results are consistent with the literature showing GRIN1 underexpression in schizophrenic disorders as well as an increased risk of cervical, bladder, and kidney cancers and lymphoma during ASCL3 underexpression. The effect of allele A of the –27G>A SNP (rs1195040887) in the NOS1 promoter is suggestive of an increased risk of ischemic damage to the brain in carriers. A comparison of experimental TBP–TATA affinity values (KD) of wild-type and minor alleles with predicted ones showed that the data correlate well (linear correlation coefficient r = 0.94, p < 0.01).

The GluN1 subunit of the N-methyl-d-aspartate (NMDA) receptor is encoded by GRIN1 gene. Mutations in this gene can cause neurodevelopmental disorders with or without hyperkinetic movements and seizures. It can be inherited as either autosomal dominant (NDHMSD) or autosomal recessive (NDHMSR). Patients can present with severe psychomotor delay, seizures, behavioral problems, stereotypies, and oculogyric crisis (OGC). There is emerging evidence regarding the molecular interaction between dopamine and NMDA receptors, cross-talk between dopamine and glutamate signaling, and mutations in GRIN1 could affect both glutamatergic and dopaminergic synaptic transmission. Dopamine antagonists, such as risperidone, which is used to treat behavioral problems, can cause extrapyramidal side effects, including OGC. Here, we present a case of an 8-year-old boy with a GRIN1 variant who was treated with risperidone for severe behavioral problems and experienced an OGC for approximately 30 h. The child had no prior history of such event and experienced no re-occurrences after discontinuing risperidone. This case highlights the importance of exercising extra caution while prescribing dopamine antagonists for patients with GRIN1 mutations and reports the efficacy of memantine in treating seizures and behavioral side effects in such patients. In the era of precision medicine, this case represents a good example of how patient's genetic makeup should be considered in prescribing the right medication for the right patient.

[Display omitted] Neuropathic pain is a highly prevalent and refractory condition, yet its mechanism remains poorly understood. While NR1, the essential subunit of NMDA receptors, has long been recognized for its pivotal role in nociceptive transmission, its involvement in presynaptic stimulation is incompletely elucidated. Transcription factors can regulate the expression of both pro-nociceptive and analgesic factors. Our study shows that transcription factor TFAP2A was up-regulated in the dorsal root ganglion (DRG) neurons, satellite glial cells (SGCs), and Schwann cells following spinal nerve ligation (SNL). Intrathecal injection of siRNA targeting Tfap2a immediately or 7 days after SNL effectively alleviated SNL-induced pain hypersensitivity and reduced Tfap2a expression levels. Bioinformatics analysis revealed that TFAP2A may regulate the expression of the Grin1 gene, which encodes NR1. Dual-luciferase reporter assays confirmed TFAP2A's positive regulation of Grin1 expression. Notably, both Tfap2a and Grin1 were expressed in the primary SGCs and upregulated by lipopolysaccharides. The expression of Grin1 was also down-regulated in the DRG following Tfap2a knockdown. Furthermore, intrathecal injection of siRNA targeting Grin1 immediately or 7 days post-SNL effectively alleviated SNL-induced mechanical allodynia and thermal hyperalgesia. Finally, intrathecal Tfap2a siRNA alleviated SNL-induced neuronal hypersensitivity, and incubation of primary SGCs with Tfap2a siRNA decreased NMDA-induced upregulation of proinflammatory cytokines. Collectively, our study reveals the role of TFAP2A- Grin1 in regulating neuropathic pain in peripheral glia, offering a new strategy for the development of novel analgesics. [ABSTRACT FROM AUTHOR]

N-methyl-D-aspartate receptors are ionotropic glutamate receptors that mediate synaptic transmission and plasticity. Variable GluN2 subunits in diheterotetrameric receptors with identical GluN1 subunits set very different functional properties. To understand this diversity, we use single-molecule fluorescence resonance energy transfer (smFRET) to measure the conformations of the ligand binding domain and modulatory amino-terminal domain of the common GluN1 subunit in receptors with different GluN2 subunits. Our results demonstrate a strong influence of the GluN2 subunits on GluN1 rearrangements, both in non-agonized and partially agonized activation intermediates, which have been elusive to structural analysis, and in the fully liganded state. Chimeric analysis reveals structural determinants that contribute to these subtype differences. Our study provides a framework for understanding the conformational landscape that supports highly divergent levels of activity, desensitization, and agonist potency in receptors with different GluN2s and could open avenues for the development of subtype-specific modulators. [Display omitted] • smFRET reveals conformational differences between NMDA receptors with different GluN2s • Low-P o receptors are more splayed at rest and more compact when fully agonized • Interaction between the GluN1 LBD and GluN2 NTD contributes to these differences Bleier et al. use single-molecule fluorescence resonance energy transfer (smFRET) in NMDA receptors to compare conformations and rearrangements of receptor subtypes with different GluN2 subunits. They find that low-open-probability receptors are more splayed and dynamic at rest, more compact when fully agonized, and show distinct subunit interactions. [ABSTRACT FROM AUTHOR]

Background: Ionotropic glutamate NMDA receptors are multi-subunit proteins with few selective pharmacological ligands and are tentatively implicated in MS and other neurodegenerative disorders. The present study was aimed at evaluating the antioxidant properties of Berberis vulgaris extract-loaded magnetite nanoparticles on the Grin1 gene expression in NMDA receptor in EAE Syrian mice. Methods: EAE mice models were generated through active immunization with MBP and PTx and kept for days 9-14 until EAE signs appeared followed by administration of barberry extract loaded magnetic nanoparticles. Results: Pure BE concentrations did not show recovery signs until days 7-9, but partial recovery in tail movement was seen on days 11 and 14, which was significant as compared to the control group in terms of improvement of the clinical scores. Meanwhile bare nanoparticles had neither disease recovery/progression properties nor EAE mice mortality as compared to controls, but 1 mg BE + Fe3O4 reduced EAE symptom severity and resulted in significant improvement of hind limb sensitivity to toe pinching and improved tail movements. Meanwhile 2 mg Be + Fe3O4 showed much better sensitivity to toe pinching and complete tail recovery. qRT-PCR analysis showed a significant decrease in relative Grin1 expression in female mice after treatment with 0.2 and 1 mg BE. However, a profound decrease in Grin1 expression was seen at 0.2, 1 and 2 mg BE + Fe3O4 treated groups in a dose-dependent manner. Conclusion: The results indicated that Fe3O4+ BE could alleviate the EAE severity and progression

Background: The number of reports on GRIN1 variants associated with neurodevelopmental phenotypes has increased in recent years. However, there are only two detailed reports on electroencephalography findings. Case study: We had a case with severe global developmental delay, and exome sequencing revealed a novel de novo heterozygous variant of GRIN1. The patient's electroencephalography showed unique findings: paroxysmal fast activity—20–30 Hz beta waves, independently in the bilateral occipital regions, sometimes in a continuous manner—and prolonged alpha activity in the bilateral frontal regions, observed mainly during sleep, those findings were observed persistently. Discussion: The electroencephalography findings of our case have not been reported in the past. Receptor hypofunction due to the GRIN1 variant and imbalance in excitatory/inhibitory transmission owing to the dysfunction of the N-methyl-D-aspartate receptors may be the mechanism for the global developmental delay, stereotyped movements, and development of paroxysmal fast activity in our case. Accumulation of additional case reports is needed to confirm the reproducibility of the electroencephalography findings for disease specificity.

The development and function of sensory systems require intact glutamatergic neurotransmission. Changes in touch sensation and vision are common symptoms in autism spectrum disorders, where altered glutamatergic neurotransmission is strongly implicated. Further, cortical visual impairment is a frequent symptom of GRIN disorder, a rare genetic neurodevelopmental disorder caused by pathogenic variants of GRIN genes that encode NMDA receptors. We asked if Grin1 knockdown mice (Grin1KD), as a model of GRIN disorder, had visual impairments resulting from NMDA receptor deficiency. We discovered that Grin1KD mice had deficient visual depth perception in the visual cliff test. Since Grin1KD mice are known to display robust changes in measures of learning, memory, and emotionality, we asked whether deficits in these higher‐level processes could be partly explained by their visual impairment. By changing the experimental conditions to improve visual signals, we observed significant improvements in the performance of Grin1KD mice in tests that measure spatial memory, executive function, and anxiety. We went further and found destabilization of the outer segment of retina together with the deficient number and size of Meissner corpuscles (mechanical sensor) in the hind paw of Grin1KD mice. Overall, our findings suggest that abnormal sensory perception can mask the expression of emotional, motivational and cognitive behavior of Grin1KD mice. This study demonstrates new methods to adapt routine behavioral paradigms to reveal the contribution of vision and other sensory modalities in cognitive performance. [ABSTRACT FROM AUTHOR]

Pathogenic variants in glutamate receptor, ionotropic, NMDA‐1 (GRIN1) cause an autosomal dominant or recessive neurodevelopmental disorder with global developmental delay, with or without seizures (AD or AR GRIN1‐NDD). Here, we describe a novel homozygous canonical splice site variant in GRIN1 in a 12‐month‐old boy with early infantile epileptic encephalopathy and severe global developmental delay. This represents only the second family with a homozygous predicted‐null variant in GRIN1 reported to date. We review the published literature on AR GRIN1‐NDD and find that the phenotype in our patient is much more severe than those seen with homozygous missense variants. A similarly severe phenotype of intractable epilepsy and infantile death has only been reported in one other family with a homozygous nonsense variant in GRIN1. We, therefore, propose that biallelic predicted‐null variants in GRIN1 can cause a markedly more severe clinical phenotype than AR GRIN1‐NDD caused by missense variants. [ABSTRACT FROM AUTHOR]

Dysregulation of microRNA (miRNA) biogenesis is involved in drug addiction. Argonaute2 (Ago2), a specific splicing protein involved in the generation of miRNA, was found to be dysregulated in the nucleus accumbens (NAc) of methamphetamine (METH)-sensitized mice in our previous study. Here, we determined whether Ago2 in the NAc regulates METH sensitization in mice and identified Ago2-dependent miRNAs involved in this process. We found a gradual reduction in Ago2 expression in the NAc following repeated METH use. METH-induced hyperlocomotor activity in mice was strengthened by knocking down NAc neuronal levels of Ago2 but reduced by overexpressing Ago2 in NAc neurons. Surprisingly, miR-3068-5p was upregulated following overexpression of Ago2 and downregulated by silencing Ago2 in the NAc. Knocking down miR-3068-5p, serving as an Ago2-dependent miRNA, strengthened the METH sensitization responses in mice. These findings demonstrated that dysregulated Ago2 in neurons in the NAc is capable of regulating METH sensitization and suggested a potential role of Ago2-dependent miR-3068-5p in METH sensitization. [ABSTRACT FROM AUTHOR]

Cue-induced cocaine craving gradually intensifies following abstinence, a phenomenon known as the incubation of drug craving. Neuronal ensembles activated by initial cocaine use, are critically involved in this process. However, the mechanisms by which neuronal changes occurring in the ensembles after withdrawal contribute to incubation remain largely unknown. Here we labeled neuronal ensembles in the shell of nucleus accumbens (NAcSh) activated by cocaine conditioned place preference (CPP) training. NAcSh ensembles showed an increasing activity induced by CPP test after 21-day withdrawal. Inhibiting synaptic transmission of NAcSh ensembles suppressed the preference for cocaine paired-side after 21-day withdrawal, demonstrating a critical role of NAcSh ensembles in increased preference for cocaine. The density of dendritic spines in dopamine D1 receptor expressing ensembles was increased after 21-day withdrawal. Moreover, the expression of Grin1 , a subunit of the N-methyl-D-aspartate (NMDA) receptor, specifically increased in the NAcSh ensembles after cocaine withdrawal in both CPP and self-administration (SA) mouse models. Targeted knockdown or dysfunction of Grin1 in NAcSh ensembles significantly suppressed craving for cocaine. Our results suggest that the accumulation of NMDA receptors in NAcSh ensembles mediates increased craving for cocaine after prolonged withdrawal, thereby providing potential molecular targets for treatment of drug addiction. [Display omitted] ● Activity of NAcSh ensembles is enhanced by CPP test after prolonged withdrawal, alongside enhanced preference for cocaine. ● Inhibition of synaptic transmission of NAcSh ensembles decreases preference for cocaine side after prolonged withdrawal. ● Dendritic spine density is increased in NAcSh D1-ensembles after prolonged withdrawal. ● Grin1 expression is up-regulated in NAcSh neuronal ensembles after prolonged withdrawal. ● Down-regulation or dysfunction of Grin1 in NAcSh neuronal ensembles decreases preference for cocaine. [ABSTRACT FROM AUTHOR]

NMDA receptors (NMDARs) are glutamate‐gated ion channels that contribute to nearly all brain processes. Not surprisingly then, genetic variations in the genes encoding NMDAR subunits can be associated with neurodevelopmental, neurological and psychiatric disorders. These disease‐associated variants (DAVs) present challenges, such as defining how DAV‐induced alterations in receptor function contribute to disease progression and how to treat the affected individual clinically. As a starting point to overcome these challenges, we need to refine our understanding of the complexity of NMDAR structure function. In this regard, DAVs have expanded our knowledge of NMDARs because they do not just target well‐known structure‐function motifs, but rather give an unbiased view of structural elements that are important to the biology of NMDARs. Indeed, established NMDAR structure‐function motifs have been validated by the appearance of disorders in patients where these motifs have been altered, and DAVs have identified novel structural features in NMDARs such as gating triads and hinges in the gating machinery. Still, the majority of DAVs remain unexplored and occur at sites in the protein with unidentified function or alter receptor properties in multiple and unanticipated ways. Detailed mechanistic and structural investigations are required of both established and novel motifs to develop a highly refined pathomechanistic model that accounts for the complex machinery that regulates NMDARs. Such a model would provide a template for rational drug design and a starting point for personalized medicine. [ABSTRACT FROM AUTHOR]

Rationale: Previous studies suggested that methionine (Met) levels are decreased in depressed patients. However, whether the decrease in this amino acid is important for phenotypic behaviors associated with depression has not been deciphered. Objective: The response of individuals to chronic stress is variable, with some individuals developing depression and others becoming resilient to stress. In this study, our objective was to examine the effect of Met on susceptibility to stress. Methods: Male C57BL/6J mice were subjected to daily defeat sessions by a CD1 aggressor, for 10 days. On day 11, the behavior of mice was assessed using social interaction and open-field tests. Mice received Met 4 h before each defeat session. Epigenetic targets were assessed either through real-rime RTPCR or through Western Blots. Results: Met did not modulate anxiety-like behaviors, but rather promoted resilience to chronic stress, rescued social avoidance behaviors and reversed the increase in the cortical expression levels of N-methyl-d-aspartate receptor (NMDAR) subunits. Activating NMDAR activity abolished the ability of Met to promote resilience to stress and to rescue social avoidance behavior, whereas inhibiting NMDAR did not show any synergistic or additive protective effects. Indeed, Met increased the cortical levels of the histone methyltransferase SETDB1, and in turn, the levels of the repressive histone H3 lysine (K9) trimethylation (me3). Conclusions: Our data indicate that Met rescues susceptibility to stress by inactivating cortical NMDAR activity through an epigenetic mechanism involving histone methylation. [ABSTRACT FROM AUTHOR]

NMDA receptor dysfunction is central to the encephalopathies caused by missense mutations in the NMDA receptor subunit genes. Missense variants of GRIN1, GRIN2A, and GRIN2B cause similar syndromes with varying severity of intellectual impairment, autism, epilepsy, and motor dysfunction. To gain insight into possible biomarkers of NMDAR hypofunction, we asked whether a loss-of-function variant in the Grin1 gene would cause structural changes in the brain that could be detected by MRI. We also studied the developmental trajectory of these changes to determine whether structural changes coincided with reported cognitive impairments in the mice. We performed magnetic resonance imaging in male Grin1−/− knockdown mice (GluN1KD) that were three, six, or twelve weeks old. Deformation-based morphometry was used to assess neuroanatomical differences. Volumetric reductions were detected in substantia nigra and striatum of GluN1KD mice at all ages. Changes in limbic structures were only evident at six weeks of age. Reductions in white matter volumes were first evident at three weeks, and additional deficits were detected at six and twelve weeks. FluoroJade immunofluorescence revealed degenerating neurons in twelve-week old GluN1KD mice. We conclude that Grin1 loss-of-function mutations cause volume reductions in dopaminergic structures early in development, while changes to limbic and white matter structures are delayed and are more pronounced in post-adolescent ages. The evidence of degenerating neurons in the mature brain indicates an ongoing process of cell loss as a consequence of NMDAR hypofunction.

Abstract Background This study aimed to investigate the new genetic etiologies of Rett syndrome (RTT) or Rett‐like phenotypes. Methods Targeted next‐generation sequencing (NGS) was performed on 44 Chinese patients with RTT or Rett‐like phenotypes, in whom genetic analysis of MECP2, CDKL5, and FOXG1 was negative. Results The detection rate was 31.8% (14/44). A de novo pathogenic variant (c.275_276ins AA, p. Cys92*) of KIF1A was identified in a girl with all core features of typical RTT. A patient with atypical RTT was detected having de novo GRIN1 pathogenic variant (c.2337C > A, p. Val793Phe). Additionally, compound heterozygous pathogenic variants of PPT1 gene were detected in a girl, who initially displayed typical RTT features, but progressed into neuronal ceroid lipofuscinoses (NCL) afterwards. Pathogenic variants in KCNQ2, MEF2C, WDR45, TCF4, IQSEC2, and SDHA were also found in our cohort. Conclusions It is the first time that pathogenic variants of GRIN1 and KIF1A were linked to RTT and Rett‐like profiles. Our findings expanded the genetic heterogeneity of Chinese RTT or Rett‐like patients, and also suggest that some patients with genetic metabolic disease such as NCL, might displayed Rett features initially, and clinical follow‐up is essential for the diagnosis.

Objective To explore the effects of different doses of metformin hydrochloride on behavior and candidate gene expression in mouse model of schizophrenia so as to provide new ideas and clues for clinical treatment of schizophrenia. Methods First, 50 C57 BL/6 J mice of the same batch were randomly divided into five groups as blank control group, negative control group, and three metformin hydrochloride experimental groups(low dose 200 mg/kg, medium dose 400 mg/kg, and high dose 800 mg/kg), with 10 mice in each group. In addition, except the blank control group, all the other groups were injected intraperitoneally with dizocepin maleate(MK-801), N-methyl-D-aspartate glutamate(NMDA) receptor non-competitive antagonist. Meanwhile, metformin hydrochloride was given prophylactically at the same time in the three metformin hydrochloride experimental groups. Then, the five groups of mice were subjected to ethology experiments such as elevated plus maze, open field test, and Morris water maze. Finally, the mice’s brain tissues were extracted as soon as they were killed for detection of the expressions of AMPK,GRIN1,HDAC1 and DGCR8 at the mRNA level by RT-qPCR.Results In all the ethologic experiments,significant differences were found between the blank control group and the negative control group(P<0.05),which suggested that the experimental animal model had been successfully constructed.In the elevated plus maze test and open field test,there was a major disparity between the high-dose metformin hydrochloride experimental group and the negative control group(P <0.01),which indicated that high-dose metformin hydrochloride had a great alleviating effect on anxiety symptoms of schizophrenia induced by MK-801.At the same time,RT-qPCR results showed that high-dose metformin could proportionally increase the expression levels of AMPK and GRIN1(P<0.001),thus reversing the trend of decreased expressions of these genes in the negative control group.Conclusion High-dose metformin hydrochloride can alleviate abnormal behavior in schizophrenic model mice,and it may play an important role through AMPK and GRIN1 related signal pathways,thus providing new ideas and clues for the clinical treatment of schizophrenia. [ABSTRACT FROM AUTHOR]

The activation of the endocannabinoid system controls the release of many neurotransmitters involved in the brain reward pathways, including glutamate. Both endocannabinoid and glutamate systems are crucial for alcohol relapse. In the present study, we hypothesize that N-methyl-D-aspartate (NMDA) glutamate receptors regulate the ability of a priming dose of WIN 55,212-2 to cross-reinstate ethanol-induced conditioned place preference (CPP). To test this hypothesis, ethanol-induced (1.0 g/kg, 10% w/v, i.p.) CPP (unbiased method) was established using male adult Wistar rats. After CPP extinction, one group of animals received WIN 55,212-2 (1.0 and 2.0 mg/kg, i.p.), the cannabinoid receptor 1 (CB1) agonist, or ethanol, and the other group received memantine (3.0 or 10 mg/kg, i.p.), the NMDA antagonist and WIN 55,212-2 on the reinstatement day. Our results showed that a priming injection of WIN 55,212-2 (2.0 mg/kg, i.p.) reinstated (cross-reinstated) ethanol-induced CPP with similar efficacy to ethanol. Memantine (3.0 or 10 mg/kg, i.p.) pretreatment blocked this WIN 55,212-2 effect. Furthermore, our experiments indicated that ethanol withdrawal (7 days withdrawal after 10 days ethanol administration) down-regulated the CNR1 (encoding CB1), GRIN1/2A (encoding GluN1 and GluN2A subunit of the NMDA receptor) genes expression in the prefrontal cortex and dorsal striatum, but up-regulated these in the hippocampus, confirming the involvement of these receptors in ethanol rewarding effects. Thus, our results show that the endocannabinoid system is involved in the motivational properties of ethanol, and glutamate may control cannabinoid induced relapse into ethanol seeking behavior.

The cumulative damage caused by repetitive mild traumatic brain injury can cause long-term neurodegeneration leading to cognitive impairment. This cognitive impairment is thought to result specifically from damage to the hippocampus. In this study, we detected cognitive impairment in mice 6 weeks after repetitive mild traumatic brain injury using the novel object recognition test and the Morris water maze test. Immunofluorescence staining showed that p-tau expression was increased in the hippocampus after repetitive mild traumatic brain injury. Golgi staining showed a significant decrease in the total density of neuronal dendritic spines in the hippocampus, as well as in the density of mature dendritic spines. To investigate the specific molecular mechanisms underlying cognitive impairment due to hippocampal damage, we performed proteomic and phosphoproteomic analyses of the hippocampus with and without repetitive mild traumatic brain injury. The differentially expressed proteins were mainly enriched in inflammation, immunity, and coagulation, suggesting that non-neuronal cells are involved in the pathological changes that occur in the hippocampus in the chronic stage after repetitive mild traumatic brain injury. In contrast, differentially expressed phosphorylated proteins were mainly enriched in pathways related to neuronal function and structure, which is more consistent with neurodegeneration. We identified N-methyl-D-aspartate receptor 1 as a hub molecule involved in the response to repetitive mild traumatic brain injury , and western blotting showed that, while N-methyl-D-aspartate receptor 1 expression was not altered in the hippocampus after repetitive mild traumatic brain injury, its phosphorylation level was significantly increased, which is consistent with the omics results. Administration of GRP78608, an N-methyl-D-aspartate receptor 1 antagonist, to the hippocampus markedly improved repetitive mild traumatic brain injury-induced cognitive impairment. In conclusion, our findings suggest that N-methyl-D-aspartate receptor 1 signaling in the hippocampus is involved in cognitive impairment in the chronic stage after repetitive mild traumatic brain injury and may be a potential target for intervention and treatment., Competing Interests: None

The Mediodorsal (MD) thalamus that represents a fundamental subcortical relay has been underrepresented in the studies focusing on the molecular changes in the brains of subjects with alcohol use disorder (AUD). In the current study, MD thalamic regions from AUD subjects and controls were analyzed with Affymetrix Clariom S human microarray. Long-term alcohol use induced a significant (FDR ≤ 0.05) upregulation of 2802 transcripts and downregulation of 1893 genes in the MD thalamus of AUD subjects. A significant upregulation of GRIN1 (glutamate receptor NMDA type 1) and FTO (alpha-ketoglutarate dependent dioxygenase) was confirmed in western blot analysis. Immunohistochemical staining revealed similar heterogenous distribution of GRIN1 in the thalamic nuclei of both AUD and control subjects. The most prevalent functional categories of upregulated genes were related to glutamatergic and GABAergic neurotransmission, cellular metabolism, and neurodevelopment. The prevalent gene cluster among down-regulated genes was immune system mediators. Forty-two differentially expressed genes, including FTO, ADH1B, DRD2, CADM2, TCF4, GCKR, DPP6, MAPT and CHRH1, have been shown to have strong associations (FDR p < 10−8) with AUD or/and alcohol use phenotypes in recent GWA studies. Despite a small number of subjects, we were able to detect robust molecular changes in the mediodorsal thalamus caused by alcohol emphasizing the importance of deeper brain structures such as diencephalon, in the development of AUD-related dysregulation of neurocircuitry.

Insulin-secreting pancreatic β-cells express proteins characteristic of D-serine regulated synapses, but the acute effect of D-serine co-agonism on its presumptive β-cell target, N-methyl D-aspartate receptors (NMDARs), is unclear. We used multiple models to evaluate glucose homeostasis and insulin secretion in mice with a systemic increase in D-serine (intraperitoneal injection or DAAO mutants without D-serine catabolism) or tissue-specific loss of Grin1-encoded GluN1, the D-serine binding NMDAR subunit. We also investigated the effects of D-serine ± NMDA on glucose-stimulated insulin secretion (GSIS) and β-cell depolarizing membrane oscillations, using perforated patch electrophysiology, in β-cell-containing primary isolated mouse islets. In vivo models of elevated D-serine correlated to improved blood glucose and insulin levels. In vitro, D-serine potentiated GSIS and β-cell membrane excitation, dependent on NMDAR activating conditions including GluN1 expression (co-agonist target), simultaneous NMDA (agonist), and elevated glucose (depolarization). Pancreatic GluN1-loss females were glucose intolerant and GSIS was depressed in islets from younger, but not older, βGrin1 KO mice. Thus, D-serine is capable of acute antidiabetic effects in mice and potentiates insulin secretion through excitatory β-cell NMDAR co-agonism but strain-dependent shifts in potency and age/sex-specific Grin1-loss phenotypes suggest that context is critical to the interpretation of data on the role of D-serine and NMDARs in β-cell function.

GRIN1 encodes the obligate subunit (GluN1) of glutamate N-methyl- d -aspartate receptor (NMDAr). Pathogenic variants in GRIN1 are a well-known cause of infantile encephalopathy characterized by profound developmental delay (DD), variable epileptic phenotypes, and distinctive behavioral abnormalities. Recently, GRIN1 has also been implicated in the pathogenesis of polymicrogyria (PMG). We investigated two patients presenting with severe intellectual disability (ID), epilepsy, stereotyped movements, and abnormal ocular movements. They showed distinctive circadian rhythm alterations and sleep-wake patterns anomalies characterized by recurrent cyclic crying or laughing spells. Genetic analysis led to the identification of two distinct de novo variants in GRIN1 affecting the same amino acid residue of an important functional protein domain. Recent advances in circadian rhythm and sleep regulation suggest that abnormal GluN1 function might play a relevant pathogenetic role for the peculiar behavioral abnormalities observed in GRIN1 patients. Our cases highlight the relevance of circadian rhythm abnormalities in epileptic children as a clue toward GRIN1 encephalopathy and expand the complex phenotypic spectrum of this severe genetic disorder. • GRIN1 encodes the obligate subunit of glutamate N-methyl- d -aspartate receptor (NMDAr). • GRIN1 deficiency causes a severe early-onset epileptic encephalopathy. • This study describes distinctive circadian rhythm alterations in GRIN1 patients. • Sleep-wake anomalies and cyclic crying or laughing spells might foster early diagnosis. • Manipulating glutamate metabolism might be a therapeutic approach in GRIN1 patients. [ABSTRACT FROM AUTHOR]

Organophosphates insecticides (OPs) are common surface water contaminants in both urban and agricultural landscapes. Neurobehavioral effects on larval fish are known to occur at concentrations higher than those reported in the environment. The aim of this study was to perform a comparative analysis of neurobehavioral, molecular, and biochemical responses of four OPs (diazinon, dichlorvos, malathion, methyl-parathion) via the following endpoint measurements: distance traveled, velocity, gene expression (AChE, c-Fos, LINGO-1B, GRIN-1B), enzymatic acetylcholinesterase (AChE) activity, and carboxylesterase (CES) activity. OP exposures (5 hpf - 120 dpf) on embryo-larval zebrafish (Danio rerio) were assessed using a larval zebrafish behavior assay at concentrations: 0.01, 0.1, 10, and 100 μg/L. Individual OPs had varying degrees of neurotoxicity. Significant hypoactivity was observed in the 100 μg/L treatments for diazinon and malathion (p < 0.05) as compared to the controls. Diazinon-exposed larvae exhibited a 26% locomotor decrease, and hypoactivity was observed in malathion-exposed larvae at a reduction of 22% and 29% for distance traveled and velocity, respectively. Gene regulation and enzymatic activity changes were measured for both 0.1 and 100 μg/L exposures across OP treatments. Increased CES activity was observed for the 0.1 μg/L treatments of diazinon and methyl-parathion as well as the 100 μg/L treatment of dichlorvos; meanwhile, decreased CES activity was observed for 100 μg/L treatments of diazinon and malathion. Relative enzymatic activity of AChE was inhibited as compared to the control for the 0.1 μg/L diazinon. No other treatment group exhibited a significant effect on biochemical AChE activity; however, AChE upregulation was observed in the 0.1 μg/L exposure for diazinon, dichlorvos, and malathion. Methyl-parathion was observed to downregulate c-Fos at 0.1 μg/L exposure. Malathion upregulated LINGO-1B at 100 μg/L, a gene associated with neuronal regeneration; meanwhile, downregulation of LINGO-1B was observed for 0.1 μg/L exposure of methyl-parathion. Additional downregulation was observed for GRIN-1B in the 100 μg/L diazinon, 100 μg/L dichlorvos, and 0.1 μg/L methyl-parathion treatments. Exposure of ZF embryos to independent concentrations of 100 μg/L concentrations of diazinon and malathion resulted in hypoactivity and decreased CES activity at 5 dfp. No changes in swimming behavior were observed for either the 0.1 μg/L or 100 μg/L dichlorvos or methyl-parathion treatments. Observations from this study indicate that AChE inhibition may not be the most sensitive biomarker of OP pesticide exposure in zebrafish. Rather, the enzyme CES demonstrated higher sensitivity as a biomarker of OP toxicity. • Carboxylesterase is an efficient biomarker of organophosphate exposure • Diazinon and malathion induce hypoactivity of zebrafish at 100 μg/L exposure • Neurodegenerative gene changes observed at 0.1 and 100 μg/L concentrations • No behavioral, biochemical, or molecular changes of methyl-parathion at 100 μg/L [ABSTRACT FROM AUTHOR]

Supplemental Digital Content is available in the text. Background: Several lines of evidence support the hypothesis that impaired functioning of the glutamatergic N -methyl- d -aspartate receptor (NMDAR) might be involved in the etiology of schizophrenia. NMDAR is activated by phosphorylation by Fyn, and there is also some evidence to suggest that abnormalities in Fyn functionality could also be involved in susceptibility to schizophrenia. In a recent weighted burden analysis of exome-sequenced schizophrenia cases and controls, we noted modest statistical evidence for an enrichment of rare, functional variants in FYN , GRIN1 , and GRIN2B in schizophrenia cases. Aim: To test the plausibility of the hypothesis that schizophrenia susceptibility might be associated with genetic variants predicted to cause impaired functioning of NMDAR, either directly or indirectly through impairment of the kinases that phosphorylate it. Methods: In an exome-sequenced sample of 4225 schizophrenia cases and 5834 controls, rare variants occurring in genes for the NMDAR subunits and for the kinases acting on it were annotated. The counts of disruptive and damaging variants were compared between cases and controls, and the distribution of amino acids affected by damaging variants was visualised in ProteinPaint and the RCSB Protein Data Bank. Special attention was paid to tyrosine residues subject to phosphorylation. Results: There was no suggestion that abnormalities of the serine–threonine kinases or of Src were associated with schizophrenia. Overall, three cases and no controls had a disruptive variant in GRIN2A and two cases and no controls had a disruptive variant in FYN. Moreover, 14 cases and three controls had damaging variants in FYN , and all the variants in controls affected amino acid residues in the N-terminal region outside of any known functional domains. By contrast, 10 variants in cases affected amino acids in functional domains, and in the 3D structure of Fyn, two of the amino acid substitutions, A376T and Q517E, were adjacent to each other. A total of eight cases and one control had damaging variants in GRIN1 , but there was no obvious pattern with respect to particular functional domains being affected in this or other genes. A single case had a variant in GRIN2A affecting a well-supported phosphorylation site, Y943C, and three cases had a variant in FYN which produces an amino acid change, T216S, which lies two residues away from two adjacent well-supported phosphorylation sites. Aside from this, there was no suggestion that tyrosine phosphorylation sites in Fyn or NMDAR were affected. Conclusion: The numbers of variants involved are too small for firm conclusions to be drawn. The results are consistent with the hypothesis that ∼0.5% of patients with schizophrenia have disruptive or damaging genetic variants, which could plausibly impair functioning of NMDAR directly or indirectly through impairing Fyn function. [ABSTRACT FROM AUTHOR]

Kabuki syndrome is mainly caused by dominant de-novo pathogenic variants in the KMT2D and KDM6A genes. The clinical features of this syndrome are highly variable, making the diagnosis of Kabuki-like phenotypes difficult, even for experienced clinical geneticists. Herein we present molecular genetic findings of causal genetic variation using array comparative genome hybridization and a Mendeliome analysis, utilizing targeted exome analysis focusing on regions harboring rare disease-causing variants in Kabuki-like patients which remained KMT2D/KDM6A -negative. The aCGH analysis revealed a pathogenic CNV in the 14q11.2 region, while targeted exome sequencing revealed pathogenic variants in genes associated with intellectual disability ( HUWE1, GRIN1 ), including a gene coding for mandibulofacial dysostosis with microcephaly ( EFTUD2 ). Lower values of the MLL2-Kabuki phenotypic score are indicative of Kabuki-like phenotype (rather than true Kabuki syndrome), where aCGH and Mendeliome analyses have high diagnostic yield. Based on our findings we conclude that for new patients with Kabuki-like phenotypes it is possible to choose a specific molecular testing approach that has the highest detection rate for a given MLL2-Kabuki score, thus fostering more precise patient diagnosis and improved management in these genetically- and phenotypically heterogeneous clinical entities. [ABSTRACT FROM AUTHOR]

Polymicrogyria is a malformation of cortical development. The aetiology of polymicrogyria remains poorly understood. Using whole-exome sequencing we found de novo heterozygous missense GRIN1 mutations in 2 of 57 parent-offspring trios with polymicrogyria. We found nine further de novo missense GRIN1 mutations in additional cortical malformation patients. Shared features in the patients were extensive bilateral polymicrogyria associated with severe developmental delay, postnatal microcephaly, cortical visual impairment and intractable epilepsy. GRIN1 encodes GluN1, the essential subunit of the N-methyl-d-aspartate receptor. The polymicrogyria-associated GRIN1 mutations tended to cluster in the S2 region (part of the ligand-binding domain of GluN1) or the adjacent M3 helix. These regions are rarely mutated in the normal population or in GRIN1 patients without polymicrogyria. Using two-electrode and whole-cell voltage-clamp analysis, we showed that the polymicrogyria-associated GRIN1 mutations significantly alter the in vitro activity of the receptor. Three of the mutations increased agonist potency while one reduced proton inhibition of the receptor. These results are striking because previous GRIN1 mutations have generally caused loss of function, and because N-methyl-d-aspartate receptor agonists have been used for many years to generate animal models of polymicrogyria. Overall, our results expand the phenotypic spectrum associated with GRIN1 mutations and highlight the important role of N-methyl-d-aspartate receptor signalling in the pathogenesis of polymicrogyria. [ABSTRACT FROM AUTHOR]

Human use of marijuana at an early age has been reported to lead to cognitive impairment. However, researchers have not yet clearly determined whether this impairment is due to marijuana-induced alterations in the developing nervous system and whether this deficit persists into adulthood after marijuana use has ceased. We administered anandamide to developing rats to assess the effect of cannabinoids on development. We subsequently evaluated learning and performance on a temporal bisection task in adulthood and assessed the expression of genes encoding principal subunits of NMDA receptors (Grin1, Grin2A, and Grin2B) in the hippocampus and prefrontal cortex. Rats in two age groups, namely, 21-day-old and 150-day-old rats, received intraperitoneal injections of anandamide or the vehicle for 14 days. Both groups performed a temporal bisection test, which included listening to tones of different durations and classifying them as short or long. The expression of the Grin1, Grin2A and Grin2B mRNAs was evaluated using quantitative PCR in both age groups after extracting mRNA from the hippocampus and prefrontal cortex. We observed a learning impairment in the temporal bisection task (p < 0.05) and changes in the response latency (p < 0.05) in rats that received anandamide. Furthermore, these rats exhibited decreased expression of Grin2b (p = 0.001) compared to those that received the vehicle. In human subjects, the use of cannabinoids during development induces a long-term deficit, but this deficit is not observed in subjects who use cannabinoids in adulthood. Rats treated with anandamide earlier in development took longer to learn the task, suggesting that anandamide exerts a harmful effect on cognition in developing rats. Administration of anandamide during early stages of development induced deficits in learning and other cognitive processes that depend on an adequate estimation of time. The cognitive demands of the environment must be considered when evaluating the cognitive effects of cannabinoids on developing or mature brains. High cognitive demands might induce differential expression of NMDA receptors that improves cognitive capacity, overcoming altered glutamatergic function • Administration of cannabinoids during early stages of development induced permanent deficits in learning and other cognitive processes. • Cannabinoids induce a different expression of NMDA subunits in Young subjects in comparation to the adults rats. • Cognitive processes depend on an adequate estimation of time, the observed deficit could be related to increase in temporal perception by cannabinoids. [ABSTRACT FROM AUTHOR]

Profiles of alternative mRNA isoforms have been determined in three brain regions of rats from an aggressive and a tame line selected for 74 generations. Among 2319 genes with alternatively spliced exons, approximately 84% were confirmed by analyzing public databases. Based on Gene Ontology-guided clustering of alternatively spliced genes, it has been found that the sample was enriched in synapse-specific genes (FDR < 10). Patterns of gene expression in the brains of animals with genetically determined high or low aggression were more frequently found to differ in the use of alternatively spliced exons than in animals environmentally conditioned for increased or lowered propensity to aggression. For the Adcyap1r1 gene, five alternatively spliced mRNA isoforms have been represented differentially in aggressive animals. A detailed analysis of the gene that encodes glutamate ionotropic receptor NMDA type subunit 1 ( Grin1) has confirmed significant differences in the levels of its alternatively spliced isoforms in certain brain regions of tame and aggressive rats. These differences may affect the behavior in rats genetically selected for aggression levels. [ABSTRACT FROM AUTHOR]

De novo GRIN1 mutations have recently been shown to cause severe intellectual disability, hypotonia, hyperkinetic and stereotyped movements, and epilepsy. We report two new cases of severe early onset encephalopathy associated with hyperkinetic and oculogyric-like movements, caused by mutations in the GRIN1 gene; both were identified by whole exome sequencing. One of the patients harbored the novel mutation p.Ser688Tyr and the other patient harbored the p.Gly827Arg mutation, which was previously reported in three patients. In silico studies suggested that the p.Se688Tyr mutation results in disruption of NMDA ligand binding and the p.Gly827Arg mutation results in disrupted gating of the ion channel. Our study highlights the importance of GRIN1 mutations in the etiology of isolated cases of early onset encephalopathy, and the valuable role of whole exome sequencing in identifying these mutations. [ABSTRACT FROM AUTHOR]

Renal interstitial fibrosis (RIF) is the final pathway for chronic kidney diseases (CKD) to end-stage renal disease, with no ideal therapy at present. Previous studies indicated that sodium glucose co-transporter-2 inhibitor (SGLT2i) dapagliflozin had the effect of anti-RIF, but the mechanism remains elusive and the renal protective effect could not be fully explained by singly targeting SGLT2. In this study, we aimed to explore the mechanism of dapagliflozin against RIF and identify novel potential targets. Firstly, dapagliflozin treatment improved pro-fibrotic indicators in unilateral ureteral obstruction mice and transforming growth factor beta 1 induced human proximal tubular epithelial cells. Then, transcriptomics and bioinformatics analysis were performed, and results revealed that dapagliflozin against RIF by regulating inflammation and oxidative stress related signals. Subsequently, targets prediction and analysis demonstrated that glutamate ionotropic receptor NMDA type subunit 1 (GRIN1) was a novel potential target of dapagliflozin, which was related to inflammation and oxidative stress related signals. Moreover, molecular dynamics simulation revealed that dapagliflozin could stably bind to GRIN1 protein and change its spatial conformation. Furthermore, human renal samples and Nephroseq data were used for GRIN1 expression evaluation, and the results showed that GRIN1 expression were increased in renal tissues of CKD and RIF patients than controls. Additionally, further studies demonstrated that dapagliflozin could reduce intracellular calcium influx in renal tubular cells, which depended on regulating GRIN1 protein but not gene. In conclusion, GRIN1 is probably a novel target of dapagliflozin against RIF. [ABSTRACT FROM AUTHOR]