NMDA receptors (NMDA-Rs) are ionotropic glutamate receptors, which associate with LDL-receptor-related protein-1 (LRP1) to trigger cell signaling in response to protein ligands in neurons. Here, we demonstrate for the first time that the NMDA-R is expressed by rat Schwann cells and functions independently and with LRP1 to regulate Schwann cell physiology. The NR1 (encoded by GRIN1) and NR2b (encoded by GRIN2B) NMDA-R subunits were expressed by cultured Schwann cells and upregulated in sciatic nerves following crush injury. The ability of LRP1 ligands to activate ERK1/2 (also known as MAPK3 and MAPK1, respectively) and promote Schwann cell migration required the NMDA-R. NR1 gene silencing compromised Schwann cell survival. Injection of the LRP1 ligands tissue-type plasminogen activator (tPA, also known as PLAT) or MMP9-PEX into crush-injured sciatic nerves activated ERK1/2 in Schwann cells in vivo, and the response was blocked by systemic treatment with the NMDA-R inhibitor MK801. tPA was unique among the LRP1 ligands examined because tPA activated cell signaling and promoted Schwann cell migration by interacting with the NMDA-R independently of LRP1, albeit with delayed kinetics. These results define the NMDA-R as a Schwann cell signaling receptor for protein ligands and a major regulator of Schwann cell physiology, which may be particularly important in peripheral nervous system (PNS) injury.

In the wake of recent advances in scientific research, personalized medicine using deep learning techniques represents a new paradigm. In this work, our goal was to establish deep learning models which distinguish responders from non-responders, and also to predict possible antidepressant treatment outcomes in major depressive disorder (MDD). To uncover relationships between the responsiveness of antidepressant treatment and biomarkers, we developed a deep learning prediction approach resulting from the analysis of genetic and clinical factors such as single nucleotide polymorphisms (SNPs), age, sex, baseline Hamilton Rating Scale for Depression score, depressive episodes, marital status, and suicide attempt status of MDD patients. The cohort consisted of 455 patients who were treated with selective serotonin reuptake inhibitors (treatment-response rate = 61.0%; remission rate = 33.0%). By using the SNP dataset that was original to a genome-wide association study, we selected 10 SNPs (including ABCA13 rs4917029, BNIP3 rs9419139, CACNA1E rs704329, EXOC4 rs6978272, GRIN2B rs7954376, LHFPL3 rs4352778, NELL1 rs2139423, NUAK1 rs2956406, PREX1 rs4810894, and SLIT3 rs139863958) which were associated with antidepressant treatment response. Furthermore, we pinpointed 10 SNPs (including ARNTL rs11022778, CAMK1D rs2724812, GABRB3 rs12904459, GRM8 rs35864549, NAALADL2 rs9878985, NCALD rs483986, PLA2G4A rs12046378, PROK2 rs73103153, RBFOX1 rs17134927, and ZNF536 rs77554113) in relation to remission. Then, we employed multilayer feedforward neural networks (MFNNs) containing 1-3 hidden layers and compared MFNN models with logistic regression models. Our analysis results revealed that the MFNN model with 2 hidden layers (area under the receiver operating characteristic curve (AUC) = 0.8228 ± 0.0571; sensitivity = 0.7546 ± 0.0619; specificity = 0.6922 ± 0.0765) performed maximally among predictive models to infer the complex relationship between antidepressant treatment response and biomarkers. In addition, the MFNN model with 3 hidden layers (AUC = 0.8060 ± 0.0722; sensitivity = 0.7732 ± 0.0583; specificity = 0.6623 ± 0.0853) achieved best among predictive models to predict remission. Our study indicates that the deep MFNN framework may provide a suitable method to establish a tool for distinguishing treatment responders from non-responders prior to antidepressant therapy.

Increasing evidence links dysregulation of NR2B-containing N-methyl-D-aspartate receptor remodelling and trafficking to Alzheimer's disease (AD). This theme offers the possibility that the GRIN2B gene, encoding this selective NR2B subunit, represents a potential molecular modulating factor for this disease. Based on this hypothesis, we carried out a mutation scanning of exons and flanking regions of GRIN2B in a well-characterized cohort of AD patients, recruited from Southern Italy. A "de novo" p.K1293R mutation, affecting a highly conserved residue of the protein in the C-terminal domain, was observed for the first time in a woman with familial AD, as the only genetic alteration of relevance. Moreover, an association study between the other detected sequence variants and AD was performed. In particular, the study was focused on five identified single nucleotide polymorphisms: rs7301328, rs1805482, rs3026160, rs1806191 and rs1806201, highlighting a significant contribution from the GRIN2B rs1806201 T allele towards disease susceptibility [adjusted odds ratio (OR) = 1.92, 95% confidence interval (CI) 1.40-2.63, p < 0.001, after correction for sex, age, and APOE ε4 genotype]. This was confirmed by haplotype analysis that identified a specific haplotype, carrying the rs1806201 T allele (CCCTC), over-represented in patients versus controls (adjusted OR = 6.03; p < 0.0001). Although the pathogenic role of the GRIN2B-K1293R mutation in AD is not clear, our data advocate that genetic variability in the GRIN2B gene, involved in synaptic functioning, might provide valuable insights into disease pathogenesis, continuing to attract significant attention in biomedical research on its genetic and functional role.

The activity-regulated gene expression of transcription factors is required for neural plasticity and function in response to neuronal stimulation. T-brain-1 (TBR1), a critical neuron-specific transcription factor for forebrain development, has been recognized as a high-confidence risk gene for autism spectrum disorders. Here, we show that in addition to its role in brain development, Tbr1 responds to neuronal activation and further modulates the Grin2b expression in adult brains and mature neurons. The expression levels of Tbr1 were investigated using both immunostaining and quantitative reverse transcription polymerase chain reaction (RT-PCR) analyses. We found that the mRNA and protein expression levels of Tbr1 are induced by excitatory synaptic transmission driven by bicuculline or glutamate treatment in cultured mature neurons. The upregulation of Tbr1 expression requires the activation of both α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptors. Furthermore, behavioral training triggers Tbr1 induction in the adult mouse brain. The elevation of Tbr1 expression is associated with Grin2b upregulation in both mature neurons and adult brains. Using Tbr1-deficient neurons, we further demonstrated that TBR1 is required for the induction of Grin2b upon neuronal activation. Taken together with the previous studies showing that TBR1 binds the Grin2b promoter and controls expression of luciferase reporter driven by Grin2b promoter, the evidence suggests that TBR1 directly controls Grin2b expression in mature neurons. We also found that the addition of the calcium/calmodulin-dependent protein kinase II (CaMKII) antagonist KN-93, but not the calcium-dependent phosphatase calcineurin antagonist cyclosporin A, to cultured mature neurons noticeably inhibited Tbr1 induction, indicating that neuronal activation upregulates Tbr1 expression in a CaMKII-dependent manner. In conclusion, our study suggests that Tbr1 plays an important role in adult mouse brains in response to neuronal activation to modulate the activity-regulated gene transcription required for neural plasticity.

D-Serine is a unique endogenous substance enriched in the brain at the exceptionally high concentrations as a free D-amino acid in mammals throughout their life. Peripheral tissues and blood contain low or trace levels of the D-amino acid. In the nervous systems, D-serine appears to act as an intrinsic coagonist for the N-methyl-D-aspartate type glutamate receptor (NMDA receptor) based upon the following characteristics: (i) D-serine stereoselectively binds to and stimulates the glycine-regulatory site of the NMDA receptor consisting of GRIN1/GRIN2 subunits more potently than glycine with an affinity and ED50 at high nanomolar ranges, (ii) the selective elimination of D-serine in brain tissues attenuates the NMDA receptor functions, indicating an indispensable role in physiological activation of the glutamate receptor, and (iii) the distribution of D-serine is uneven and closely correlated with that of the binding densities of the various NMDA receptor sites, and especially of the GRIN2B subunit in the brain. Moreover, d-serine exerts substantial influence on the GRIN1/GRIN3-NMDA and δ2 glutamate receptor. In the brain and retina, metabolic processes of D-serine, such as biosynthesis, extracellular release, uptake, and degradation, are observed and some candidate molecules that mediate these processes have been isolated. The fact that the mode of extracellular release of D-serine in the brain differs from that of classical neurotransmitters is likely to be related to the detection of D-serine in both glial cells and neurons, suggesting that d-serine signals could be required for the glia-synapse interaction. Moreover, the findings from the basic experiments and clinical observations support the views that the signaling system of endogenous free D-serine plays important roles, at least, through the action on the NMDA receptors in the brain wiring development and the regulation of higher brain functions, including cognitive, emotional and sensorimotor function. Based upon these data, aberrant D-serine-NMDA receptor interactions have been considered to be involved in the pathophysiology of a variety of neuropsychiatric disorders including schizophrenia and ischemic neuronal cell death. The molecular and cellular mechanisms for regulating the D-serine signals in the nervous system are, therefore, suitable targets for studies aiming to elucidate the causes of neuropsychiatric disorders and for the development of new treatments for intractable neuropsychiatric symptoms.

Sequencing of the human, mouse, and rat genomes has enabled a comprehensive informatics approach to gene families. This approach is informative for identification of new members of gene families, for cross-species sequence conservation related to functional conservation, for within-species diversity related to functional variation, and for historical effects of selection. This genome informatics approach also focuses our attention on genes whose genomic locations coincide with linkages to phenotypes. We are identifying ionotropic glutamate receptor (IGR) sequence variation by resequencing technologies, including denaturing high-performance liquid chromoatography (dHPLC), for screening and direct sequencing, and by information mining of public (e.g., dbSNP and ENSEMBL) and private (i.e., Celera Discovery System) sequence databases. Each of the 16 known IGRs is represented in these databases, their positions on a canonical physical map (for example, the Celera map) are established, and comparison to mouse and rat sequences has been performed, revealing substantial conservation of these genes, which are located on different chromosomes but found within syntenic groups of genes. A collection of 38 missense variants were identified by the informatics and resequencing approaches in several of these receptor genes, including GRIN2B, GRIN3B, GRIA2, GRIA3, and GRIK1. This represents only a fraction of the sequence variation across these genes, but, in fact, these may constitute a large fraction of the common polymorphisms at these genes, and these polymorphisms are a starting point for understanding the role of these receptors in neurogenetic variation. Genetically influenced human neurobehavioral phenotypes that are likely to be linked to IGR genetic variants include addictions, anxiety/dysphoria disorders, post-brain injury behavioral disorders, schizophrenia, epilepsy, pain perception, learning, and cognition. Thus, the effects of glutamate receptor variation may be protean, and the task of relating variation to behavior difficult. However, functional variants of (1) catechol-O-methyltransferase, (2) serotonin transporter, and (3) brain-derived neurotrophic factor have recently been linked both to behavioral differences and to intermediate phenotypes, suggesting a pathway by which functional variation at IGRs can be tied to an etiologically complex phenotype.

OBJECTIVE

Impulse control disorders (ICD) are commonly associated with dopamine replacement therapy (DRT) in patients with Parkinson's disease (PD). Our aims were to estimate ICD heritability and to predict ICD by a candidate genetic multivariable panel in patients with PD.

METHODS

Data from de novo patients with PD, drug-naïve and free of ICD behaviour at baseline, were obtained from the Parkinson's Progression Markers Initiative cohort. Incident ICD behaviour was defined as positive score on the Questionnaire for Impulsive-Compulsive Disorders in PD. ICD heritability was estimated by restricted maximum likelihood analysis on whole exome sequencing data. 13 candidate variants were selected from the DRD2, DRD3, DAT1, COMT, DDC, GRIN2B, ADRA2C, SERT, TPH2, HTR2A, OPRK1 and OPRM1 genes. ICD prediction was evaluated by the area under the curve (AUC) of receiver operating characteristic (ROC) curves.

RESULTS

Among 276 patients with PD included in the analysis, 86% started DRT, 40% were on dopamine agonists (DA), 19% reported incident ICD behaviour during follow-up. We found heritability of this symptom to be 57%. Adding genotypes from the 13 candidate variants significantly increased ICD predictability (AUC=76%, 95% CI (70% to 83%)) compared to prediction based on clinical variables only (AUC=65%, 95% CI (58% to 73%), p=0.002). The clinical-genetic prediction model reached highest accuracy in patients initiating DA therapy (AUC=87%, 95% CI (80% to 93%)). OPRK1, HTR2A and DDC genotypes were the strongest genetic predictive factors.

CONCLUSIONS

Our results show that adding a candidate genetic panel increases ICD predictability, suggesting potential for developing clinical-genetic models to identify patients with PD at increased risk of ICD development and guide DRT management.

Patient phenotypes in pharmacological pain treatment varies between individuals, which could be partly assigned to their genotypes regarding the targets of classical analgesics (OPRM1, PTGS2) or associated signalling pathways (KCNJ6). Translational and genetic research have identified new targets, for which new analgesics are being developed. This addresses voltage-gated sodium, calcium and potassium channels, for which SCN9A, CACNA1B, KCNQ2 and KCNQ3, respectively, are primary gene candidates because they code for the subunits of the respective channels targeted by analgesics currently in clinical development. Mutations in voltage gated transient receptor potential (TRPV) channels are known from genetic pain research and may modulate the effects of analgesics under development targeting TRPV1 or TRPV3. To this add ligand-gated ion channels including nicotinic acetylcholine receptors, ionotropic glutamate-gated receptors and ATP-gated purinergic P2X receptors with most important subunits coded by CHRNA4, GRIN2B and P2RX7. Among G protein coupled receptors, δ-opioid receptors (coded by OPRD1), cannabinoid receptors (CNR1 and CNR2), metabotropic glutamate receptors (mGluR5 coded by GRM5), bradykinin B(1) (BDKRB1) and 5-HT(1A) (HTR1A) receptors are targeted by new analgesic substances. Finally, nerve growth factor (NGFB), its tyrosine kinase receptor (NTRK1) and the fatty acid amide hydrolase (FAAH) have become targets of interest. For most of these genes, functional variants have been associated with neuro-psychiatric disorders and not yet with analgesia. However, research on the genetic modulation of pain has already identified variants in these genes, relative to pain, which may facilitate the pharmacogenetic assessments of new analgesics. The increased number of candidate pharmacogenetic modulators of analgesic actions may open opportunities for the broader clinical implementation of genotyping information.

Extrahepatic cholangiocarcinoma (EHC) is usually difficult to diagnose by bile cytology because of cellular disintegration. However, DNA samples from bile fluid can provide sufficient materials to screen for the presence of EHC. We developed DNA methylation marker panels that can be used for MethyLight assay-based detection of EHC in bile fluid specimens. The methylation status of 59 DNA methylation markers was investigated in 20 EHC and 20 non-neoplastic gallbladder tissue samples with MethyLight assay to determine cancer-specific DNA methylation markers. Through assaying cancer-specific DNA methylation markers in a training set (n = 40) and validation set (n = 45) of bile fluid specimens from patients with EHC or those without cancer, we selected suitable marker panels that were assessed for their performance in a third set (test set; n = 40). Four marker panels showed a sensitivity of 60% or more and a specificity of 100% in both the training and validation sets, whereas bile cytology displayed a sensitivity of 40% to 46% and a specificity of 100%. In an independent test set of bile fluid samples, a five-gene panel (CCND2, CDH13, GRIN2B, RUNX3, and TWIST1) detected EHC at a sensitivity of 83%, which was far higher than that of bile cytology (46%, P = 0.004). Using bile fluids, a methylation assay consisting of a five-gene panel may be useful for detecting EHC and in helping to increase the sensitivity of preoperative diagnoses.

Microglia polarization to the classical M1 activation state is characterized by elevated pro-inflammatory cytokines; however, a full profile has not been generated in the early stages of a sterile inflammatory response recruiting only resident microglia. We characterized the initial M1 state in a hippocampal injury model dependent upon tumor necrosis factor (TNF) receptor signaling for dentate granule cell death. Twenty-one-day-old CD1 male mice were injected with trimethyltin (TMT 2.3 mg/kg, i.p.) and the hippocampus was examined at an early stage (24-h post-dosing) of neuronal death. Glia activation was assessed using a custom quantitative nuclease protection assay. We report elevated mRNA levels for glia response such as ionizing calcium-binding adapter molecule-1 and glial fibrillary acidic protein (Gfap); Fas, hypoxia inducible factor alpha, complement component 1qb, TNF-related genes (Tnf, Tnfaip3, Tnfrsfla); interleukin-1 alpha, Cd44, chemokine (C-C motif) ligand (Ccl)2, Cc14, integrin alpha M, lipocalin (Lcn2), and secreted phosphoprotein 1 (Spp1). These changes occurred in the absence of changes in matrix metalloproteinase 9 and 12, neural cell adhesion molecule, metabotropic glutamate receptor (Grm)3, and Ly6/neurotoxin 1 (Lynx1), as well as, a decrease in neurotrophin 3, glutamate receptor subunit epsilon (Grin)-2b, and neurotrophic tyrosine kinase receptor, type 3. The M2 anti-inflammatory marker, transforming growth factor beta-1 (Tgfb1) was elevated. mRNAs associated with early stage of injury-induced neurogenesis including fibroblast growth factor 21 and Mki67 were elevated. In the "non-injured" temporal cortex receiving projections from the hippocampus, Lynx1, Grm3, and Grin2b were decreased and Gfap increased. Formalin fixed-paraffin-embedded tissue did not generate a comparable profile.

Genetic, environmental and neurodevelopmental factors are thought to underlie the onset of neuropsychiatric disorders such as schizophrenia. How these risk factors collectively contribute to pathology is unclear. Here, we present a mouse model of prenatal intracerebral hemorrhage--an identified risk factor for schizophrenia--using a serum-exposure paradigm. This model exhibits behavioral, neurochemical and schizophrenia-related gene expression alterations in adult females. Behavioral alterations in amphetamine-induced locomotion, prepulse inhibition, thigmotaxis and social interaction--in addition to increases in tyrosine hydroxylase-positive dopaminergic cells in the substantia nigra and ventral tegmental area and decreases in parvalbumin-positive cells in the prefrontal cortex--were induced upon prenatal serum exposure. Lysophosphatidic acid (LPA), a lipid component of serum, was identified as a key molecular initiator of schizophrenia-like sequelae induced by serum. Prenatal exposure to LPA alone phenocopied many of the schizophrenia-like alterations seen in the serum model, whereas pretreatment with an antagonist against the LPA receptor subtype LPA1 prevented many of the behavioral and neurochemical alterations. In addition, both prenatal serum and LPA exposure altered the expression of many genes and pathways related to schizophrenia, including the expression of Grin2b, Slc17a7 and Grid1. These findings demonstrate that aberrant LPA receptor signaling associated with fetal brain hemorrhage may contribute to the development of some neuropsychiatric disorders.

Impulse control disorders (ICD) are reported to occur at variable frequencies in different ethnic groups. Genetic vulnerability is suspected to underlie the individual risk for ICD. We investigated whether the allelic variants of dopamine (DRD3), glutamate (GRIN2B) and serotonin (HTR2A) receptors are linked to ICD in Indian Parkinson's disease (PD) patients.

We conducted a prospective, case-control study which included PD patients (70 with ICD, 100 without ICD categorized after direct psychiatric interview of patient and caregiver) and 285 healthy controls. Single nucleotide polymorphism (SNP) variants of DRD3 p.S9G (rs6280), GRIN2B c.2664C>T (rs1806201) and HTR2A c.102T>C (rs6313) were genotyped.

Multivariate regression analysis revealed that DRD3 p.Ser9Gly (rs6280) heterozygous variant CT (OR = 2.22, 95% CI: 1.03-4.86, p = 0.041), higher daily Levodopa equivalent doses (LED) of drugs (for 100 mg LED, OR = 1.14, 95% CI: 1.01-1.29, p = 0.041), current dopamine agonist but not Levodopa use (OR = 2.16, 95% CI: 1.03-4.55, p = 0.042) and age of onset of motor symptoms under 50 years (OR 2.09, 95% CI: 1.05-4.18, p = 0.035) were independently associated with ICD.

DRD3 p.Ser9Gly (rs6280) CT genotype is associated with ICD in Indian PD patients and this association is novel. Enhanced D3 receptor affinity due to gain-of-function conferred by the glycine residues could impair reward-risk assessment in the mesolimbic system and contribute to development of impulsive behaviour, in carriers of this genotype.

The small cell ovarian carcinoma of the hypercalcemic type (SCCOHT) represents an aggressive tumor with poor prognosis predominantly affecting young women and so far, no cell line or animal model is available to investigate this devastating disease. Biopsy material from a recurrent SCCOHT was subjected to an explant culture to obtain an adherent and continuously proliferating cell population. Morphological and functional characterization revealed a heterogeneous population (SCCOHT-1) of about 13 µm in diameter and approximately 36 h of doubling time. Flow cytometric analysis of surface markers demonstrated the expression of CD15, CD29, CD44 and CD90 paralleled by the presence of cytokeratins and vimentin. Cytogenetic analysis and high-resolution oligo-array comparative genomic hybridization (aCGH) demonstrated a stable karyotype including deletions of the PARK2, CSMD1, GRIN2B and ATF7IP genes. Following lentiviral transduction with a GFP vector, the labeled SCCOHT-derived cells were subjected to CCE to separate distinct subpopulations as evidenced by cell cycle analysis. Subcutaneous injection of these subpopulations into NOD/SCID mice exhibited hypercalcemia and a tumor development in 100% of the mice. Re-cultivation of the mouse tumors revealed an outgrowth of SCCOHT-derived phenotypes and all cell populations expressed high telomerase activity. Moreover, histopathological evaluation demonstrated close similarities between the mouse tumors and the original patient tumor. In conclusion, SCCOHT-1 cells provide a study platform to investigate this rare disease and to examine effective and sufficient therapeutic strategies for this rather unknown type of cancer.

OBJECTIVE

We had previously performed a genome-wide linkage scan for bipolar affective disorder in an Ashkenazi Jewish sample, a population likely to have reduced genetic heterogeneity. This study is a second stage follow-up focusing on regions that showed positive linkage scores in our previous scan but were not fine-mapped at that time.

METHODS

We genotyped an additional 145 highly polymorphic microsatellites and conducted linkage analyses using standard laboratory and analytical methods.

RESULTS

We saw an improvement of the evidence for linkage in most regions, with the most notable change on chromosome 12p13.1-p12.3, where the evidence of linkage is now suggestive. This region harbors the gene encoding the ionotropic glutamate receptor subunit 2B (GRIN2B), a gene that previously yielded evidence for association in a candidate gene study on 323 Ashkenazi Jewish bipolar case-parent trios. We find that the evidence for linkage is significantly correlated with the presence of the putative high-risk allele identified in our candidate gene study.

CONCLUSIONS

Following up weaker signals can significantly improve linkage signals even after relatively small increases in information content. Our results on chromosome 12p support GRIN2B as a candidate gene for bipolar disorder that needs further investigation.

A well established model for the pathophysiology of schizophrenia postulates a role for the NMDA-mediated glutamate transmission. The human gene coding for the 2B subunit of the NMDA receptor (GRIN2B) is considered a candidate based on its selective expression in brain. To evaluate the hypothesis that GRIN2B acts as a major gene in determining susceptibility to schizophrenia, a case-control association study was performed. Five single nucleotide polymorphisms (SNPs) were genotyped in 188 Italian patients and 156 control subjects. The association study showed a marginally significant excess of homozygosity for the polymorphism located in the 3'UTR region (P = 0.04). No other difference in genotype and allele frequencies was found in schizophrenics as compared to the control series. The case-control study was also carried out on estimated haplotypes, confirming a trend for association (P = 0.04). These results suggest that GRIN2B variations might be linked with susceptibility to schizophrenia. Replication studies on larger samples are warranted to further test this hypothesis.

The present study characterizes the involvement of the N-methyl-D-aspartic acid receptors (NMDARs) in mediating thermal hyperalgesia induced by activation of group I metabotropic glutamate receptors (mGluRs). Intrathecal administration of the mGluR1/5 agonist (S)-3,5-DHPG [(S)-3,5-dihydroxyphenylglycine] to mice resulted in significant hyperalgesia as assessed by the tail immersion test. The pretreatment of mice i.t. with CGS 19755 (selective antagonist of the NMDAR), CGP 78608 [[(1S)-1-[[(7-bromo-1,2,3,4-tetrahydro-2,3-dioxo-5-quinoxalinyl)methyl]amino]ethyl]phosphonic acid] (selective antagonist at the glycine-binding site of the NMDAR), ifenprodil and Ro 25-6981 (selective antagonists of the NR2B subunit of the NMDAR), bisindolylmaleimide I and Go-7874 [12-(2-cyanoethyl)-6,7,12,13-tetrahydro-13-methyl-5-oxo-5H-indolo(2,3-a)pyrrolo(3,4-c)-carbazole] (inhibitors of protein kinase C), or PKI-(14-22)-amide [Myr-N-Gly-Arg-Thr-Gly-Arg-Arg-Asn-Ala-Ile-NH(2)] (inhibitor of protein kinase A) dose-dependently inhibited the hyperalgesia induced by i.t. administration of the mGluR1/5 receptor agonist (S)-3,5-DHPG. In contrast, i.t. pretreatment of mice with NVP-AAM077 [[(R)-[(S)-1-(4-bromophenyl)-ethylamino]-(2,3-dioxo-1,2,3,4-tetrahydroquinoxalin-5-yl)-methyl]-phosphonic acid] (selective antagonist of the NR2A subunit of the NMDAR) or DT-3 [H-Arg-Gln-Ile-Lys-Ile-Trp-Phe-Gln-Asn-Arg-Arg-Met-Lys-Trp-Lys-Lys-Leu-Arg-Lys-Lys-Lys-Lys-Lys-His-OH] (inhibitor of protein kinase G) had no effect on (S)-3,5-DHPG-mediated hyperalgesia. We also show for the first time that i.t. injection of pSM2 (pShag Magic version 2)-grin2b (coding for an short-hairpin RNA to the NR2B subunit of the NMDAR) resulted in a dose-dependent decrease in the NR2B protein and blockade of hyperalgesia induced by activation of the mGluR1/5 in (S)-3,5-DHPG-treated mice. Taken together, our results suggest the hypothesis that mGluRs are coupled to the NMDAR channels through the NR2B subunit in the spinal cord and that this coupling involves the activation of protein kinase C and protein kinase A.

The N-methyl-D-aspartate (NMDA) receptor 2B gene (GRIN2B) was studied as a candidate gene of alcoholism. This study aimed to investigate the association between each of the three GRIN2B polymorphisms (rs1806201, rs1805247, and rs1805502) and alcoholism. This study included 206 alcoholic patients and 189 unrelated control subjects of Korean origin. Associations between genotype, allele, and haplotype frequencies of the polymorphisms and alcoholism were investigated. The genotype frequencies of rs1806201 and the haplotype analysis of SNPs in this study show significantly differences between the case and controls. These findings suggest new candidate SNPs in GRIN2B for studying the genetic susceptibility to alcoholism.

OBJECTIVE

To compare genome-wide methylation profiles in maternal leukocyte DNA between normotensive and preeclamptic pregnant women at delivery.

METHODS

Age, body mass index matched case-control comparison of methylation at 27,578 cytosine-- guanine sites in 14,495 genes in maternal leukocyte DNA in women with preeclampsia (PE; n = 14) and normotensive controls (n = 14).

RESULTS

PE was associated with widespread differential methylation favoring hypermethylation. Pathway analysis identified the best matched process as a neuropeptide signaling pathway (p < 10(-5)); best matched disease as eclampsia (p < 9.97 × 10(-20)). Significantly differentially methylated genes (GRIN2b. GABRA1. PCDHB7, and BEX1) are associated with seizures.

CONCLUSIONS

Altered maternal leukocyte DNA methylation is associated with PE at delivery, and differential methylation of certain neuronal genes may explain the risk for eclampsia.

The Consortium on the Genetics of Schizophrenia Family Study (COGS-1) has previously reported our efforts to characterize the genetic architecture of 12 primary endophenotypes for schizophrenia. We now report the characterization of 13 additional measures derived from the same endophenotype test paradigms in the COGS-1 families. Nine of the measures were found to discriminate between schizophrenia patients and controls, were significantly heritable (31 to 62%), and were sufficiently independent of previously assessed endophenotypes, demonstrating utility as additional endophenotypes. Genotyping via a custom array of 1536 SNPs from 94 candidate genes identified associations for CTNNA2, ERBB4, GRID1, GRID2, GRIK3, GRIK4, GRIN2B, NOS1AP, NRG1, and RELN across multiple endophenotypes. An experiment-wide p value of 0.003 suggested that the associations across all SNPs and endophenotypes collectively exceeded chance. Linkage analyses performed using a genome-wide SNP array further identified significant or suggestive linkage for six of the candidate endophenotypes, with several genes of interest located beneath the linkage peaks (e.g., CSMD1, DISC1, DLGAP2, GRIK2, GRIN3A, and SLC6A3). While the partial convergence of the association and linkage likely reflects differences in density of gene coverage provided by the distinct genotyping platforms, it is also likely an indication of the differential contribution of rare and common variants for some genes and methodological differences in detection ability. Still, many of the genes implicated by COGS through endophenotypes have been identified by independent studies of common, rare, and de novo variation in schizophrenia, all converging on a functional genetic network related to glutamatergic neurotransmission that warrants further investigation.

The present study investigated regulation of histone acetylation by L-type voltage-dependent calcium channels (VDCCs), one of the machineries to provide Ca(2+) signals. Acetylation of histone through the phosphorylation of protein kinase Cγ (PKCγ) in the development of methamphetamine (METH)-induced place preference was demonstrated in the limbic forebrain predominantly but also in the nucleus accumbens of α1C subunit knockout mice. Chronic administration of METH produced a significant place preference in mice, which was dose-dependently inhibited by both chelerythrine (a PKC inhibitor) and nifedipine (an L-type VDCC blocker). Protein levels of acetylated histone H3 and p-PKCγ significantly increased in the limbic forebrain of mice showing METH-induced place preference, and it was also significantly attenuated by pre-treatment with chelerythrine or nifedipine. METH-induced place preference was also significantly attenuated by deletion of half the α1C gene, which is one of the subunits forming Ca(2+) channels. Furthermore, increased acetylation of histone H3 was found in specific gene-promoter regions related to synaptic plasticity, such as Nrxn, Syp, Dlg4, Gria1, Grin2a, Grin2b, Camk2a, Creb, and cyclin-dependent kinase 5, in wild-type mice showing METH-induced place preference, while such enhancement of multiple synaptic plasticity genes was significantly attenuated by a deletion of half the α1C gene. These findings suggest that L-type VDCCs play an important role in the development of METH-induced place preference by facilitating acetylation of histone H3 in association with enhanced expression of synaptic plasticity genes via PKCγ phosphorylation following an increase in the intracellular Ca(2+) concentration.

N-methyl-d-aspartate (NMDA) receptors play crucial roles in glutamate-mediated synaptic transmission and plasticity and are involved in a variety of brain functions. Specific single nucleotide polymorphisms (SNPs) in the genes encoding NMDA receptor subunits have been associated with some neuropsychiatric disorders involving altered glutamate transmission, but how these polymorphisms impact on synaptic function in humans is unknown. Here, the role of NMDA receptors in the control of cortical excitability and plasticity was explored by comparing the response to single, paired, and repetitive transcranial magnetic stimulations of the motor cortex in 77 healthy subjects carrying specific allelic variants of the NR1 subunit gene (GRIN1 rs4880213 and rs6293) or of the NR2B subunit gene (GRIN2B rs7301328, rs3764028, and rs1805247). Our results showed that individuals homozygous for the T allele in the rs4880213 GRIN1 SNP had reduced intracortical inhibition, as expected for enhanced glutamatergic excitation in these subjects. Furthermore, individuals carrying the G allele in the rs1805247 GRIN2B SNP show greater intracortical facilitation and greater long-term potentiation-like cortical plasticity after intermittent -burst stimulation. Our results provide novel insights into the function of NMDA receptors in the human brain and might contribute to the clarification of the synaptic bases of severe neuropsychiatric disorders associated with defective glutamate transmission.

BACKGROUND

Schizophrenia is a heritable disorder, however clear genetic architecture has not been detected. To overcome this state of uncertainty, the SZGene database has been established by including all published case-control genetic association studies appearing in peer-reviewed journals. In the current study, we aimed to determine if genetic variants strongly suggested by SZGene are associated with risk of schizophrenia in our case-control samples of Japanese ancestry. In addition, by employing the additive model for aggregating the effect of seven variants, we aimed to verify the genetic heterogeneity of schizophrenia diagnosed by an operative diagnostic manual, the DSM-IV.

METHODS

Each positively suggested genetic polymorphism was ranked according to its p-value, then the seven top-ranked variants (p < 0.0005) were selected from DRD2, DRD4, GRIN2B, TPH1, MTHFR, and DTNBP1 (February, 2007). 407 Schizophrenia cases and 384 controls participated in this study. To aggregate the vulnerability of the disorder based on the participants' genetic information, we calculated the "risk-index" by adding the number of genetic risk factors.

RESULTS

No statistically significant deviation between cases and controls was observed in the genetic risk-index derived from all seven variants on the top-ranked polymorphisms. In fact, the average risk-index score in the schizophrenia group (6.5+/-1.57) was slightly lower than among controls (6.6+/-1.39).

CONCLUSIONS

The current work illustrates the difficulty in identifying universal and definitive risk-conferring polymorphisms for schizophrenia. Our employed number of samples was small, so we can not preclude the possibility that some or all of these variants are minor risk factors for schizophrenia in the Japanese population. It is also important to aggregate the updated positive variants in the SZGene database when the replication work is conducted.

Several candidate modifier genes which, in addition to the pathogenic CAG repeat expansion, influence the age at onset (AO) in Huntington disease (HD) have already been described. The aim of this study was to replicate association of variations in the N-methyl D-aspartate receptor subtype genes GRIN2A and GRIN2B in the "REGISTRY" cohort from the European Huntington Disease Network (EHDN). The analyses did replicate the association reported between the GRIN2A rs2650427 variation and AO in the entire cohort. Yet, when subjects were stratified by AO subtypes, we found nominally significant evidence for an association of the GRIN2A rs1969060 variation and the GRIN2B rs1806201 variation. These findings further implicate the N-methyl D-aspartate receptor subtype genes as loci containing variation associated with AO in HD.

OBJECTIVE

Dysfunction in glutamate signalling is thought to play a role in the pathophysiology of bipolar disorder (BD). There is evidence of associations between single nucleotide polymorphisms (SNPs) in GRM3, GRIN2B, and DAOA genes and the diagnosis of BD. In this pilot study, we investigated the frequency of SNP variants in these 3 genes within South African population groups, and assessed interactions between genes and phenotypes of BD disease severity.

METHODS

Multiplex SNaPshotTM PCR was used to genotype 191 case and 188 control samples. Cases comprised of 191 individuals in a South African cohort of mixed ancestry and Caucasians, with BD Type 1. Phenotypes of BD disease severity were: age of onset, number of illness episodes, number of hospitalisations for depression or mania and history of psychotic symptoms.

RESULTS

There were no significant difference in SNP allele frequencies between cases and controls. In the case-only analysis, the GRM3 rs6465084 heterozygote was associated with a 4-fold increased risk of lifetime history of psychotic symptoms, and the specific variants within the gene pair, DAOA and GRIN2B, had a significant interaction with the number of hospitalisations for mania, with lowest admission rates associated with both pairs of ancestral alleles.

CONCLUSIONS

In BD, variations in glutamatergic genes may influence phenotypes related to the severity of illness. Speculatively, newly derived genes associated with various evolutionary advantages, may also increase the risk for more severe BD. These preliminary findings deserve validation in a larger cohort.