Association analysis of GRIN1 and GRIN2B polymorphisms and Parkinson's disease in a hospital-based case–control study

Gene expression analysis reveals GRIN1, SYT1, and SYN2 as significant therapeutic targets and drug repurposing reveals lorazepam and lorediplon as potent inhibitors to manage Alzheimer's disease

Alzheimer's disease (AD) is a slowly progressive neurodegenerative disease and a leading cause of dementia. We aim to identify key genes for the development of therapeutic targets and biomarkers for potential treatments for AD. Meta-analysis was performed on six microarray datasets and identified the differentially expressed genes between healthy and Alzheimer's disease samples. Thereafter, we filtered out the common genes which were present in at least four microarray datasets for downstream analysis. We have constructed a gene-gene network for the common genes and identified six hub genes. Furthermore, we investigated the regulatory mechanisms of these hub genes by analysing their interaction with miRNAs and transcription factors. The gene ontology analysis results highlighted the enriched terms significantly associated with hub genes. Through an extensive literature survey, we found that three of the hub genes including GRIN1, SYN2, and SYT1 were critically involved in disease development. To leverage existing drugs for potential repurposing, we predicted drug-gene interaction using the drug-gene interaction database, and performed molecular docking studies. The docking results revealed that the drug compounds had strong interactions and favorable binding with selected hub genes. Lorazepam exhibits a binding energy of -7.3 kcal/mol with GRIN1, Lorediplon exhibits binding energies of -7.7 kcal/mol and -6.3 kcal/mol with the SYT1, and SYN2 respectively. In addition, 100 ns molecular dynamics simulations were carried out for the top complexes and apo protein as well. Furthermore, the MM-PBSA free energy calculations also revealed that these complexes are stable and had favorable energies. According to our study, the identified hub gene could serve as a biomarker as well as a therapeutic target for AD, and the proposed repurposed drug molecules appear to have promising efficacy in treating the disease.Communicated by Ramaswamy H. Sarma.

Identification of immune signatures in Parkinson's disease based on co-expression networks

Parkinson's disease (PD) is a common neurodegenerative disease in middle-aged and elderly people, and there is less research on the relationship between immunity and PD. In this study, the protein-protein interaction networks (PPI) data, 2747 human immune-related genes (HIRGs), 2078 PD-related genes (PDRGs), and PD-related datasets (GSE49036 and GSE20292) were downloaded from the Human Protein Reference Database (HPRD), Amigo 2, DisGeNET, and Gene Expression Omnibus (GEO) databases, respectively. An immune- or PD-directed neighbor co-expressed network construction (IOPDNC) was drawn based on the GSE49036 dataset and HPRD database. Furthermore, a PD-directed neighbor co-expressed network was constructed. Modular clustering analysis was performed on the genes of the gene interaction network obtained in the first step to obtain the central core genes using the GraphWeb online website. The modules with the top 5 functional scores and the number of core genes greater than six were selected as PD-related gene modules. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of different module genes were performed. The single sample Gene Set Enrichment Analysis (ssGSEA) algorithm was used to calculate the immune cell infiltration of the PD and the normal samples. The quantitative Reverse Transcription Polymerase Chain Reaction (qRT-PCR) was performed to investigate the expression of module genes. An IOPDNC and PD-directed neighbor co-expressed network (PDNC network) were constructed. Furthermore, a total of 5 immune-PD modules were identified which could distinguish between PD and normal samples, and these module genes were strongly related to PD in protein interaction level or gene expression level. In addition, functional analysis indicated that module genes were involved in various neurodegenerative diseases, such as Alzheimer disease, Huntington disease, Parkinson disease, and Long-term depression. In addition, the genes of the 6 modules were significantly associated with these 4 differential immune cells (aDC cells, eosinophils, neutrophils, and Th2 cells). Finally, the result of qRT-PCR manifested that the expression of 6 module genes was significantly higher in normal samples than in PD samples. In our study, the immune-related genes were found to be strongly related to PD and might play key roles in PD.

Systems pharmacology, proteomics and in vivo studies identification of mechanisms of cerebral ischemia injury amelioration by Huanglian Jiedu Decoction

ETHNOPHARMACOLOGICAL RELEVANCE

Huanglian Jiedu Decoction (HLJDD) has the effect of clearing heat and detoxifying, and has been considered as an effective prescription for cerebral ischemia (CI) for thousands of years in traditional Chinese medicine (TCM). It can improve the quality of life of patients with ischemic stroke, but its pharmacological mechanism remains unclear.

AIM OF THE STUDY

The study aimed to explore the pharmacological action and potential mechanism of HLJDD against CI by systems pharmacology, proteomics and in vivo experiments.

MATERIALS AND METHODS

In this study, databases such as TCMIP V2.0 and Genecards were used to predict compounds, targets and CI related targets, and network topology criteria of protein-protein interaction (PPI) network was used to screen core targets. The Database for Annotation, Visualization and Integrated Discovery database (DAVID) was used to discover biological processes and pathways. In addition, molecular docking was performed between the screened core biological active compounds and targets to verify the binding activity. Finally, proteomics and Western blot were performed on cerebral cortex tissues of middle cerebral artery occlusion (MCAO) model rats with HLJDD intervention to further verify the predicted results.

RESULTS

77 compounds and 308 targets of HLJDD were identified, 54 of which were predicted to be associated with cerebral ischemia. PPI network and enrichment results showed that 8 targets, including AKT1, PTGS2 and TLR4, were core targets of HLJDD in CI. And 19 signaling pathways, including Rap1 signaling pathway, cAMP signaling pathway and arachidonic acid metabolism, were identified as key pathways to the therapeutic activity of HLJDD in CI. Combined with proteomics studies, we identified that Rap1 signaling pathway and upstream and downstream targets were the key mechanisms. Molecular biology experiments showed that RAP1A and AKT expression levels were significantly up-regulated in middle cerebral artery occlusion (MCAO) rats treated with HLJDD (P < 0.0001), GRIN1 expression level was significantly down-regulated (P < 0.0001). However, ACTB expression level was slightly down-regulated (P > 0.05), which may be related to the biological function.

CONCLUSION

This study confirms the pharmacological effect of HLJDD on cerebral ischemia. These results indicate that HLJDD mediates various pathways such as inhibition of apoptosis, regulation of oxygen balance, inhibition of excitatory toxicity and maintenance of basic cell functions to improve CI by regulating Rap1 signaling pathway.

The effect of human GRIN1 gene 5' functional region on gene expression regulation in vitro

INTRODUCTION

Abnormal expression of ionotropic glutamate receptor NMDA type subunit 1, the key subunit of the NMDA receptor, may be related to many neuropsychiatric disorders. In this study, we explored the functional sequence of the 5' regulatory region of the human GRIN1 gene and discussed the transcription factors that may regulate gene expression.

MATERIALS AND METHODS

Twelve recombinant pGL3 vectors with gradually truncated fragment lengths were constructed, transfected into HEK-293, U87, and SK-N-SH cell lines, and analyzed through the luciferase reporter gene assay. JASPAR database is used to predict transcription factors.

RESULTS

In SK-N-SH and U87 cell lines, regions from -337 to -159 bp, -704 to -556 bp inhibited gene expression, while -556 to -337 bp upregulated gene expression. In HEK-293 and U87 cell lines, the expression of fragment -1703 to + 188 bp was significantly increased compared to adjacent fragments -1539 to + 188 bp and -1843 to + 188 bp. The protein expressions of fragments -2162 to + 188 bp and -2025 to + 188 bp, -1539 to + 188 bp and -1215 to + 188 bp, -1215 to + 188 bp and -1066 to + 188 bp were significantly different in HEK-293 and SK-N-SH cells. According to the predictions of the JASPAR database, the transcription factors REST, EGR1, and CREB1/HIC2 may bind the DNA sequences of GRIN1 gene from the -337 to -159, -556 to -337, and -704 to -556, respectively. In addition, zinc finger transcription factors may regulate the expression of other differentially expressed fragments.

CONCLUSIONS

Abnormal transcription regulation in the proximal promoter region of GRIN1 (-704 to + 188 bp) may be involved in the course of neuropsychiatric diseases.

Association between NMDA gene polymorphism (rs4880213) and GRIN2B blood serum levels in thyroid pathology patients

The article discusses a new hypothesis that autoimmune diseases of the thyroid gland can lead to depression and neurological complications. It is believed that the neuronal N-methyl-D-aspartate receptor plays a significant role in depression pathophysiology and neurological and mental diseases, respectively. The study involved 153 patients with various forms of thyroid pathology. GRIN2B levels in the sera of the patients and healthy individuals were quantified using enzyme-linked immunosorbent assay with highly sensitive Human GRIN2B (Glutamate Receptor, Ionotropic, N-Methyl-D-Aspartate 2B) ELISA Kit. Genotyping of the glutamate ionotropic receptor NMDA type subunit 1, GRIN1 (rs4880213) gene polymorphism. The CT genotype of the NMDA gene (rs4880213) was predominant in the surveyed population. The C allele of the NMDA gene was more frequent than the T allele among patients with thyroid disease. GRIN2B levels were significantly decreased in patients with postoperative hypothyroidism 3.45 times, and in patients with AIT-induced hypothyroidism, there was a probable increase in GRIN2B levels by 1.58 times compared with controls. GRIN2B levels were significantly different in patients of different groups depending on thyroid pathology. Our study showed direct close correlation (r=0.635) between GRIN2B and anti-TPO levels (p<0.001), a significant direct close correlation (r=0.527) between GRIN2B and anti-TG levels in the blood (p<0.001). Our results allow us to consider the GRIN2B level as an important prognostic minimally invasive marker of neurological complications in endocrine pathology.

Study of Early Onset Schizophrenia: Associations of GRIN2A and GRIN2B Polymorphisms

BACKGROUND

Schizophrenia is a complex mental disorder with a high heritability. Dysfunction of the N-methyl-D-aspartate (NMDA)-type glutamate receptors may be involved in the pathogenesis of schizophrenia. In this study, we examined the contribution of GRIN2A and GRIN2B (Glutamate Ionotropic Receptor NMDA Type Subunit 2A/2B) polymorphisms to the clinical features of schizophrenia, such as the leading symptoms, the type of course, and the age of onset.

METHODS

A population of 402 Russian patients with schizophrenia from the Siberian region was investigated. Genotyping of seventeen single-nucleotide polymorphisms (SNPs) in GRIN2A and GRIN2B was performed using QuantStudio™ 3D Digital PCR System Life Technologies amplifier using TaqMan Validated SNP Genotyping Assay kits (Applied Biosystems). The results were analyzed using Chi-square and the Fisher's exact tests.

RESULTS

We found an association of GRIN2A rs7206256 and rs11644461 and GRIN2B rs7313149 with the early onset (before the age of 18 years old) schizophrenia. We did not reveal any associations of GRIN2A and GRIN2B polymorphisms with leading (positive vs. negative) symptoms or type of course (continuous vs. episodic) of schizophrenia.

CONCLUSIONS

In the study, we confirmed the involvement of the GRIN2A and GRIN2B genes in the early onset of schizophrenia in a Russian population of the Siberian region.

Weighted gene co-expression network analysis identifies specific modules and hub genes related to Parkinson's disease

OBJECTIVE

Parkinson's disease (PD) is one of the most common neurodegenerative diseases. This study aims to screen specific modules and key genes related to PD.

METHODS

Gene expression profile data GSE6613 and GSE22491 were downloaded from the Gene Expression Omnibus database. The significantly differentially expressed genes (DEGs) in different datasets were screened, followed by gene ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. The Weighted Gene Co-expression Network Analysis (WGCNA) was used to screen disease-related modules that are significantly stable across datasets. The protein-protein interaction network was constructed using the DEGs in the stable module obtained and preservation modules. Finally, the hub genes directly related to PD were screened.

RESULTS

A total of 179 DEGs with the same significant difference direction were screened. The enrichment analysis of GO and KEGG pathways showed that 20 significantly related GO biological processes and 9 KEGG signaling pathways were screened. A total of three highly conservative modules were detected in the WGCNA network. Finally, three significant PD-related KEGG pathways screened from the Comparative Toxicogenomics Database were identified, including neuroactive ligand-receptor interaction (CRHR2, CTSG, GRIN1, GRIN2D, LPAR4 and P2RX3), amyotrophic lateral sclerosis (BCL2, GRIN1 and GRIN2D) and alcoholism (CAMKK2, GRIN1, GRIN2D and SLC18A2). Key genes, such as SLC18A2, GRIN1 and GRIN2D, may be potential candidate genes for PD progression.

CONCLUSIONS

Our findings indicate that SLC18A2, GRIN1 and GRIN2D may play an important role in the pathogenesis of PD.

GRIN2A and GRIN2B and Their Related Phenotypes

Glutamate is the most relevant excitatory neurotransmitter of the central nervous system; it binds with several receptors, including N-methyl-D-aspartate receptors (NMDARs), a subtype of ionotropic glutamate receptor that displays voltage-dependent block by Mg2+ and a high permeability to Ca2+. GRIN2A and GRIN2B genes encode the GluN2A and GluN2B subunits of the NMDARs, which play important roles in synaptogenesis, synaptic transmission, and synaptic plasticity, as well as contributing to neuronal loss and dysfunction in several neurological disorders. Recently, individuals with a range of childhood-onset drug-resistant epilepsies, such as Landau–Kleffner or Lennox–Gastaut syndrome, intellectual disability (ID), and other neurodevelopmental abnormalities have been found to carry mutations in GRIN2A and GRIN2B, with high variable expressivity in phenotype. The first one is found mainly in epilepsy-aphasia syndromes, while the second one mainly in autism, schizophrenia, and ID, such as autism spectrum disorders. Brain magnetic resonance imaging alterations are found in some patients, even if without a clear clinical correlation. At the same time, increasing data on genotype–phenotype correlation have been found, but this is still not fully demonstrated. There are no specific therapies for the treatment of correlated NMDARs epilepsy, although some evidence with memantine, an antagonist of glutamate receptor, is reported in the literature in selected cases with mutation determining a gain of function.

The associations of zinc and GRIN2B genetic polymorphisms with the risk of dyslexia

BACKGROUND

Zinc is an essential trace element and a number of studies have identified the importance of zinc in neurodevelopment in children. However, epidemiologic data on the associations of zinc and genetic susceptibility with the risk of dyslexia are limited. We aimed to investigate whether genetic polymorphisms in GRIN2B genes modify the association between zinc levels and dyslexia risk.

METHODS

A case-control study of 240 dyslexic children and 230 healthy controls was conducted in Wuhan, Hangzhou and Jining city in China from April 2017 to April 2018. Zinc concentrations in urine samples were measured with inductively coupled plasma-mass spectrometry (ICPMS). Multiple imputation was used to impute missing values of covariates. We applied multivariable logistic regression models to evaluate the effect in the study.

RESULTS

After adjustment for potential confounders, we observed the associations of urinary zinc with dyslexia risk were modified by rs1805502 (P_interaction = 0.048) in gene GRIN2B. About 2-fold increase in creatinine-corrected zinc levels was significantly related to a reduced risk of dyslexia [odds ratio (OR) = 0.53, 95% confidence interval (CI): 0.29, 0.95 in rs1805502 mutation carriers].

CONCLUSIONS

The associations between zinc levels and dyslexia risk were modified by polymorphism of rs1805502 in gene GRIN2B.

Detecting Common Pathways and Key Molecules of Neurodegenerative Diseases from the Topology of Molecular Networks

MotivationNeurodegenerative diseases (NDs), including amyotrophic lateral sclerosis, Parkinson's disease, Alzheimer's disease, and Huntington's disease, occur as a result of neurodegenerative processes. Thus, it has been increasingly appreciated that many neurodegenerative conditions overlap at multiple levels. However, traditional clinicopathological correlation approaches to better classify a disease have met with limited success. Discovering this overlap offers hope for therapeutic advances that could ameliorate many ND simultaneously. In parallel, in the last decade, systems biology approaches have become a reliable choice in complex disease analysis for gaining more delicate biological insights and have enabled the comprehension of the higher order functions of the biological systems.ResultsToward this orientation, we developed a systems biology approach for the identification of common links and pathways of ND, based on well-established and novel topological and functional measures. For this purpose, a molecular pathway network was constructed, using molecular interactions and relations of four main neurodegenerative diseases (Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and Huntington's disease). Our analysis captured the overlapped subregions forming molecular subpathways fully enriched in these four NDs. Also, it exported molecules that act as bridges, hubs, and key players for neurodegeneration concerning either their topology or their functional role.ConclusionUnderstanding these common links and central topologies under the perspective of systems biology and network theory and greater insights are provided to uncover the complex neurodegeneration processes.

Mouse brain transcriptome responses to inhaled nanoparticulate matter differed by sex and APOE in Nrf2-Nfkb interactions

The neurotoxicity of air pollution is undefined for sex and APOE alleles. These major risk factors of Alzheimer's disease (AD) were examined in mice given chronic exposure to nPM, a nano-sized subfraction of urban air pollution. In the cerebral cortex, female mice had two-fold more genes responding to nPM than males. Transcriptomic responses to nPM had sex-APOE interactions in AD-relevant pathways. Only APOE3 mice responded to nPM in genes related to Abeta deposition and clearance (Vav2, Vav3, S1009a). Other responding genes included axonal guidance, inflammation (AMPK, NFKB, APK/JNK signaling), and antioxidant signaling (NRF2, HIF1A). Genes downstream of NFKB and NRF2 responded in opposite directions to nPM. Nrf2 knockdown in microglia augmented NFKB responses to nPM, suggesting a critical role of NRF2 in air pollution neurotoxicity. These findings give a rationale for epidemiologic studies of air pollution to consider sex interactions with APOE alleles and other AD-risk genes.

Glutamate ionotropic receptor NMDA type subunit 2A (GRIN2A) gene polymorphism (rs4998386) and Parkinson's disease susceptibility: A meta-analysis

OBJECTIVE

Dopaminergic neuronal degeneration seen in Parkinson's disease (PD) might result from a single nucleotide polymorphism (SNP) in the glutamate ionotropic receptor NMDA type subunit 2A (GRIN2A) gene. We thus performed a meta-analysis exploring the relationship between the rs4998386 SNP of the GRIN2A gene and PD susceptibility.

METHODS

We searched PubMed, EMBASE, Web of Science, Google Scholar, and China National Knowledge Infrastructure for studies published between January 2005 and January 2019. The association between the rs4998386 polymorphism and PD susceptibility was evaluated by calculating the pooled odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Meta-analysis results did not show a significant association between the rs4998386 polymorphism of the GRIN2A gene and PD susceptibility when assuming an allelic model (OR, 0.90; 95% CI, 0.76-1.07; P = .22; I 2 = 53%), a dominant model (OR, 0.96; 95% CI, 0.82-1.12; P = .62; I 2 = 64%), or a recessive model (OR, 1.14; 95% CI, 0.93-1.38; P = .22; I 2 = 0%).

CONCLUSION

Our meta-analysis found that the rs4998386 polymorphism of the GRIN2A gene is not associated with risk of PD in either Europeans or white Americans. However, large sample studies with different ethnicities should be conducted to establish the role of the rs4998386 polymorphism in PD pathophysiology.

Association between polymorphisms in the GRIN1 gene 5' regulatory region and schizophrenia in a northern Han Chinese population and haplotype effects on protein expression in vitro

BACKGROUND

Schizophrenia is a severe neurodevelopmental disorder with a complex genetic and environmental etiology. Abnormal glutamate ionotropic N-methyl-D-aspartate receptor (NMDA) type subunit 1 (NR1) may be a potential cause of schizophrenia.

METHODS

We conducted a case-control study to investigate the association between the GRIN1 gene, which encodes the NR1 subunit, and the risk of schizophrenia in a northern Chinese Han population using Sanger DNA sequencing. The dual luciferase reporter assay was used to detect the influence of two different haplotypes on GRIN1 gene expression.

RESULTS

Seven SNPs (single nucleotide polymorphisms), including rs112421622 (- 2019 T/C), rs138961287 (- 1962--1961insT), rs117783907 (-1945G/T), rs181682830 (-1934G/A), rs7032504 (-1742C/T), rs144123109 (-1140G/A), and rs11146020 (-855G/C) were detected in the study population. Rs117783907 (-1945G/T) was associated with the occurrence of schizophrenia as a protective factor. The genotype frequencies of rs138961287 (- 1962--1961insT) and rs11146020 (-855G/C) were statistically different between cases and controls (p < 0.0083). The other four variations were not shown to be associated with the disease. Two haplotypes were composed of the seven SNPs, and distribution of T-del-G-G-C-G-G was significantly different between the case and control groups. However, the dual luciferase reporter assay showed that neither of the haplotypes affected luciferase expression in HEK-293 and SK-N-SH cell lines.

CONCLUSIONS

The GRIN1 gene may be related to the occurrence of schizophrenia. Additional research will be needed to fully ascertain the role of GRIN1 in the etiology of schizophrenia.

Genetic findings in sport-related concussions: potential for individualized medicine?

Concussion is a traumatic transient disturbance of the brain. In sport, the initial time and severity of concussion is known giving an opportunity for subsequent analysis. Variability in susceptibility and recovery between individual athletes depends, among other parameters, on genetic factors. The genes-encoding polypeptides that determine incidence, severity and prognosis for concussion are the primary candidates for genetic analysis. Genetic polymorphisms in the genes contributing to plasticity and repair (APOE), synaptic connectivity (GRIN2A), calcium influx (CACNA1E), uptake and deposit of glutamate (SLC17A7) are potential biomarkers of concussion incidence and recovery rate. With catalogued genetic variants, prospective genotyping of athletes at the beginning of their career will allow medical professionals to improve concussion management and return-to-play decisions.

A 12p13 GRIN2B deletion is associated with developmental delay and macrocephaly

N-methyl D-aspartate receptor subtype 2B (GluN2B), encoded by GRIN2B, is one of the components of the N-methyl D-aspartate receptor protein. Aberrations in GRIN2B have been reported to be responsible for various types of neurodevelopmental disorders. We report a Japanese boy with an ~2 Mb interstitial deletion in 12p13 involving the entire GRIN2B gene, who presented with intellectual disability, motor developmental delay and marked macrocephaly.

Influence of Genetic Variants of the N-Methyl-D-Aspartate Receptor on Emotion and Social Behavior in Adolescents

Considerable evidence has suggested that the epigenetic regulation of N-methyl-D-aspartate (NMDA) glutamate receptors plays a crucial role in neuropsychiatric disorders. Previous exploratory studies have been primarily based on evidence from patients and have rarely sampled the general population. This exploratory study examined the relationship of single-nucleotide polymorphism (SNP) variations in the genes encoding the NMDA receptor (i.e., GRIN1, GRIN2A, GRIN2B, GRIN2C, and GRIN2D) with emotion and social behavior in adolescents. For this study, 832 tenth-grade Taiwanese volunteers were recruited, and their scores from the Beck Youth Inventories were used to evaluate their emotional and social impairments. Based on these scores, GRIN1 (rs4880213) was significantly associated with depression and disruptive behavior. In addition, GRIN2B (rs7301328) was significantly associated with disruptive behavior. Because emotional and social impairment greatly influence learning ability, the findings of this study provide important information for clinical treatment and the development of promising prevention and treatment strategies, especially in the area of psychological adjustment.

Identification of a Novel Rat NR2B Subunit Gene Promoter Region Variant and Its Association with Microwave-Induced Neuron Impairment

Microwave radiation has been implicated in cognitive dysfunction and neuronal injury in animal models and in human investigations; however, the mechanism of these effects is unclear. In this study, single nucleotide polymorphism (SNP) sites in the rat GRIN2B promoter region were screened. The associations of these SNPs with microwave-induced rat brain dysfunction and with rat pheochromocytoma-12 (PC12) cell function were investigated. Wistar rats (n = 160) were exposed to microwave radiation (30 mW/cm(2) for 5 min/day, 5 days/week, over a period of 2 months). Screening of the GRIN2B promoter region revealed a stable C-to-T variant at nucleotide position -217 that was not induced by microwave exposure. The learning and memory ability, amino acid contents in the hippocampus and cerebrospinal fluid, and NR2B expression were then investigated in the different genotypes. Following microwave exposure, NR2B protein expression decreased, while the Glu contents in the hippocampus and CSF increased, and memory impairment was observed in the TT genotype but not the CC and CT genotypes. In PC12 cells, the effects of the T allele were more pronounced than those of the C allele on transcription factor binding ability, transcriptional activity, NR2B mRNA, and protein expression. These effects may be related to the detrimental role of the T allele and the protective role of the C allele in rat brain function and PC12 cells exposed to microwave radiation.

DRD and GRIN2B polymorphisms and their association with the development of impulse control behaviour among Malaysian Parkinson's disease patients

Background

Impulse control disorder (ICD) and behaviours (ICB) represent a group of behavioural disorders that have become increasingly recognised in Parkinson’s disease (PD) patients who previously used dopaminergic medications, particularly dopamine agonists and levodopa. It has been suggested that these medications can lead to the development of ICB through the abnormal modulation of dopaminergic transmission and signalling in the mesocorticolimbic dopaminergic system. Several studies have reported an association between polymorphisms in the dopamine receptor (DRD) and N-methyl-D-aspartate 2B (GRIN2B) genes with the development of ICB in PD (PD-ICB) patients. Thus, this study aimed to investigate the association of selected polymorphisms within the DRD and GRIN2B genes with the development of ICB among PD patients using high resolution melt (HRM) analysis.

Method

We used high resolution melt (HRM) analysis to genotype 11 polymorphisms in 5 DRD genes [DRD1 (rs4532, rs4867798 and rs265981), DRD2 (ANKK1 rs1800497, rs104894220 and rs144999500), DRD3 (rs3732783 and rs6280), DRD4 (rs1800443), and DRD5 (rs144132215)] and 1 polymorphism in GRIN2B (rs7301328) in PD patients with (cases, n = 52) and without (controls, n = 39) ICB. Cases were obtained from two tertiary movement disorder centres [UKMMC (n = 9) and UMMC (n = 43)]. At both centres, the diagnosis of ICB was made using the QUIP questionnaire. Controls were recruited from PD patients who attended UKMMC and were found to be negative for ICB using the QUIP questionnaire.

Results

The HRM analysis showed that 7 of 11 polymorphisms [DRD1 (rs4532, rs4867798, and rs265981), DRD2 (ANKK1 rs1800497), DRD3 (rs3732783 and rs6280), and GRIN2B (rs7301328)] exhibited a clear distinction between wild-type and variant alleles. Variants of DRD2/ANKK1 rs1800497 (OR = 3.77; 95% CI, 1.38-10.30; p = 0.0044), DRD1 rs4867798 (OR = 24.53; 95% CI, 1.68-357.28; p = 0.0054), DRD1 rs4532 (OR = 21.33; 95% CI, 1.97-230.64; p = 0.0024), and GRIN2B rs7301328 (OR = 25.07; 95% CI, 1.30-483.41; p = 0.0097) were found to be associated with an increased risk of developing ICB among PD patients.

Conclusion

Our findings suggest that polymorphisms in dopamine [DRD1 (rs4532 and rs4867798) and DRD2/ANKK1 rs1800497] and glutamate (GRIN2B rs7301328) receptor genes confer increased risk of ICB development among PD patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12883-015-0316-2) contains supplementary material, which is available to authorized users.

Opposite roles of NMDA receptors in relapsing and primary progressive multiple sclerosis

Synaptic transmission and plasticity mediated by NMDA receptors (NMDARs) could modulate the severity of multiple sclerosis (MS). Here the role of NMDARs in MS was first explored in 691 subjects carrying specific allelic variants of the NR1 subunit gene or of the NR2B subunit gene of this glutamate receptor. The analysis was replicated for significant SNPs in an independent sample of 1548 MS subjects. The C allele of rs4880213 was found to be associated with reduced NMDAR-mediated cortical excitability, and with increased probability of having more disability than the CT/TT MS subjects. MS severity was higher in the CC group among relapsing-remitting MS (RR-MS) patients, while primary progressive MS (PP-MS) subjects homozygous for the T allele had more pronounced clinical worsening. Mean time to first relapse, but not to an active MRI scan, was lower in the CC group of RR-MS patients, and the number of subjects with two or more clinical relapses in the first two years of the disease was higher in CC compared to CT/TT group. Furthermore, the percentage of relapses associated with residual disability was lower in subjects carrying the T allele. Lesion load at the MRI was conversely unaffected by the C or T allele of this SNP in RR-MS patients. Axonal and neuronal degeneration at the optical coherence tomography was more severe in the TT group of PP-MS patients, while reduced retinal nerve fiber thickness had less consequences on visual acuity in RR-MS patients bearing the T allele. Finally, the T allele was associated with preserved cognitive abilities at the Rao's brief repeatable neuropsychological battery in RR-MS. Signaling through glutamate NMDARs enhances both compensatory synaptic plasticity and excitotoxic neurodegeneration, impacting in opposite ways on RR-MS and PP-MS pathophysiological mechanisms.

Differential hippocampal gene expression is associated with climate-related natural variation in memory and the hippocampus in food-caching chickadees

There is significant and often heritable variation in cognition and its underlying neural mechanisms, yet specific genetic contributions to such variation are not well characterized. Black-capped chickadees present a good model to investigate the genetic basis of cognition because they exhibit tremendous climate-related variation in memory, hippocampal morphology and neurogenesis rates throughout the North American continent, and these cognitive traits appear to have a heritable basis. We examined the hippocampal transcriptome profiles of laboratory-reared chickadees from the two most divergent populations to test whether differential gene expression in the hippocampus is associated with population differences in spatial memory, hippocampal morphology and adult hippocampal neurogenesis rates. Using high-resolution mRNA sequencing coupled to a de novo transcriptome assembly, we generated 23 295 consensus sequences, which predicted 16 206 protein sequences with 13 982 showing high similarity to known protein sequences or conserved hypothetical proteins in other species. Of these, we identified differential expression in nearly 380 genes, with 47 genes specifically linked to neurogenesis, apoptosis, synaptic function, and learning and memory processes. Many of the other differentially expressed genes, however, may be associated with other functions. Our study presents the first avian hippocampal transcriptome, and it is the first study identifying differential gene expression associated with natural variation in cognition and the hippocampus. Our results provide additional support to the hypothesis that population differences in memory, hippocampal morphology and neurogenesis in chickadees have likely resulted from natural selection that appears to act on memory and its underlying neural mechanisms.

Computational prediction of the polyQ and CAG repeat spinocerebellar ataxia network based on sequence identity to untranslated regions

Computational prediction of biological networks would be a tremendous asset to systems biology and personalized medicine. In this paper, we use a moving window bioinformatic screen to identify transcripts with partial identity to the 5' and 3'UTRs of the polyQ spinocerebellar ataxia (SCA) genes ATXN1, ATXN2, ATXN3, ATXN7, TBP and CACNA1A and the CAG repeat expansion gene PPP2R2B. We find that the bioinformatic screen enriches for transcripts that encode proteins that interact and that have functions relevant to polyQ SCA. Transcription control and RNA binding are the primary functional groups represented in the proteins from the combined screens. The insulin growth factor pathway, the WNT pathway, long term potentiation, melanogenesis and ATM mediated DNA repair pathways were identified as important pathways. UGUUU repeats were identified as an abundant motif in the SCA network and PAXIP1, CELF2, CREBBP, EBF1, PLEKHG4, SRSF4, C5orf42, NFIA, STK24, and YWHAG were identified as statistically significant proteins in the polyQ and PPP2R2B network.

Genetic variants of the NMDA receptor influence cortical excitability and plasticity in humans

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.

Variations in the GRIN2B gene are associated with risky decision-making

The dopaminergic system is known to modulate decision-making. As N-methyl-D-aspartate (NMDA) receptors strongly influence dopaminergic function, it is conceivable that the glutamatergic system is also involved in decision-making. We examined whether polymorphisms in the N-methyl-d-aspartate receptor 2B subunit gene (GRIN2B) influence decision-making using the Iowa Gambling Task (IGT). In total, 245 (n = 245, 127 female) healthy German students were included in the analysis. Two synonymous SNPs in exon 13, rs1806191 (H1178H) and rs1806201 (T888T) showed the strongest association with aspects of IGT performance. Females with a CC allele in rs1806201 made less use both of a win-stay strategy and demonstrated more exploratory behaviour during task execution. For rs1806191, we found a strong additive effect in usage of a win-stay strategy. This, partly sex-dependent, correlation of the win-stay/lose-shift behaviour with GRIN2B genotypes suggests that healthy individuals with certain GRIN2B variations respond differently to ambiguous conditions, possibly by altered perception of wins and losses. These findings underline the necessity to integrate the glutamatergic system when examining decision-making processes.

Blood gene expression correlated with tic severity in medicated and unmedicated patients with Tourette Syndrome

BACKGROUND

Tourette Syndrome (TS) has been linked to both genetic and environmental factors. Gene-expression studies provide valuable insight into the causes of TS; however, many studies of gene expression in TS do not account for the effects of medication.

MATERIALS & METHODS

To investigate the effects of medication on gene expression in TS patients, RNA was isolated from the peripheral blood of 20 medicated TS subjects (MED) and 23 unmedicated TS subjects (UNMED), and quantified using whole-genome Affymetrix microarrays.

RESULTS

D2 dopamine receptor expression correlated positively with tic severity in MED but not UNMED. GABA(A) receptor ε subunit expression negatively correlated with tic severity in UNMED but not MED. Phenylethanolamine N-methyltransferase expression positively correlated with tic severity in UNMED but not MED.

CONCLUSION

Modulation of tics by TS medication is associated with changes in dopamine, norepinephrine and GABA pathways.