Satomi Umeda-Yano

Plasma levels of mature brain-derived neurotrophic factor (BDNF) and matrix metalloproteinase-9 (MMP-9) in treatment-resistant schizophrenia treated with clozapine.

Brain-derived neurotrophic factor (BDNF) regulates the survival and growth of neurons, and influences synaptic efficiency and plasticity. Peripheral BDNF levels in patients with schizophrenia have been widely reported in the literature. However, it is still controversial whether peripheral levels of BDNF are altered in patients with schizophrenia. The peripheral BDNF levels previously reported in patients with schizophrenia were total BDNF (proBDNF and mature BDNF) as it was unable to specifically measure mature BDNF due to limited BDNF antibody specificity. In this study, we examined whether peripheral levels of mature BDNF were altered in patients with treatment-resistant schizophrenia. Matrix metalloproteinase-9 (MMP-9) levels were also measured, as MMP-9 plays a role in the conversion of proBDNF to mature BDNF. Twenty-two patients with treatment-resistant schizophrenia treated with clozapine and 22 age- and sex-matched healthy controls were enrolled. The plasma levels of mature BDNF and MMP-9 were measured using ELISA kits. No significant difference was observed for mature BDNF however, MMP-9 was significantly increased in patients with schizophrenia. The significant correlation was observed between mature BDNF and MMP-9 plasma levels. Neither mature BDNF nor MMP-9 plasma levels were associated clinical variables. Our results do not support the view that peripheral BDNF levels are associated with schizophrenia. MMP-9 may play a role in the pathophysiology of schizophrenia and serve as a biomarker for schizophrenia.

Impact on schizotypal personality trait of a genome-wide supported psychosis variant of the ZNF804A gene.

Schizophrenia is a complex disorder with a high heritability. Relatives with schizophrenia have an increased risk not only for schizophrenia but also for schizophrenia spectrum disorders, such as schizotypal personality disorder. A single nucleotide polymorphism (SNP), rs1344706, in the Zinc Finger Protein 804A (ZNF804A) gene, has been implicated in susceptibility to schizophrenia by several genome-wide association studies, follow-up association studies and meta-analyses. This SNP has been shown to affect neuronal connectivities and cognitive abilities. We investigated an association between the ZNF804A genotype of rs1344706 and schizotypal personality traits using the Schizotypal Personality Questionnaire (SPQ) in 176 healthy subjects. We also looked for specific associations among ZNF804A polymorphisms and the three factors of schizotypy-cognitive/perceptual, interpersonal and disorganization-assessed by the SPQ. The total score for the SPQ in carriers of the risk T allele was significantly higher than that in individuals with the G/G genotype (p=0.042). For the three factors derived from the SPQ, carriers with the risk T allele showed a higher disorganization factor (p=0.011), but there were no differences in the cognitive/perceptual or interpersonal factors between genotype groups (p>0.30). These results suggest that the genetic variation in ZNF804A might increase susceptibility not only for schizophrenia but also for schizotypal personality traits in healthy subjects.

Glutamate Networks Implicate Cognitive Impairments in Schizophrenia: Genome-Wide Association Studies of 52 Cognitive Phenotypes

Cognitive impairments are a core feature in patients with schizophrenia. These deficits could serve as effective tools for understanding the genetic architecture of schizophrenia. This study investigated whether genetic variants associated with cognitive impairments aggregate in functional gene networks related to the pathogenesis of schizophrenia. Here, genome-wide association studies (GWAS) of a range of cognitive phenotypes relevant to schizophrenia were performed in 411 healthy subjects. We attempted to replicate the GWAS data using 257 patients with schizophrenia and performed a meta-analysis of the GWAS findings and the replicated results. Because gene networks, rather than a single gene or genetic variant, may be strongly associated with the susceptibility to schizophrenia and cognitive impairments, gene-network analysis for genes in close proximity to the replicated variants was performed. We observed nominal associations between 3054 variants and cognitive phenotypes at a threshold of P < 1.0 × 10− 4. Of the 3054 variants, the associations of 191 variants were replicated in the replication samples (P < .05). However, no variants achieved genome-wide significance in a meta-analysis (P > 5.0 × 10− 8). Additionally, 115 of 191 replicated single nucleotide polymorphisms (SNPs) have genes located within 10 kb of the SNPs (60.2%). These variants were moderately associated with cognitive phenotypes that ranged from P = 2.50 × 10− 5 to P = 9.40 × 10− 8. The genes located within 10 kb from the replicated SNPs were significantly grouped in terms of glutamate receptor activity (false discovery rate (FDR) q = 4.49 × 10− 17) and the immune system related to major histocompatibility complex class I (FDR q = 8.76 × 10− 11) networks. Our findings demonstrate that genetic variants related to cognitive trait impairment in schizophrenia are involved in the N-methyl-d-aspartate glutamate network.

The impact of the genome-wide supported variant in the cyclin M2 gene on gray matter morphology in schizophrenia

BackgroundGenome-wide significant associations of schizophrenia with eight SNPs in the CNNM2, MIR137, PCGEM1, TRIM26, CSMD1, MMP16, NT5C2 and CCDC68 genes have been identified in a recent mega-analysis of genome-wide association studies. To date, the role of these SNPs on gray matter (GM) volumes remains unclear.MethodsAfter performing quality control for minor-allele frequency > 5% using a JPT HapMap sample and our sample, a genotyping call rate > 95% and Hardy-Weinberg equilibrium testing (p > 0.01), five of eight SNPs were eligible for analysis. We used a comprehensive voxel-based morphometry (VBM) technique to investigate the effects of these five SNPs on GM volumes between major-allele homozygotes and minor-allele carriers in Japanese patients with schizophrenia (n = 173) and healthy subjects (n = 449).ResultsThe rs7914558 risk variant at CNNM2 was associated with voxel-based GM volumes in the bilateral inferior frontal gyri (right T = 4.96, p = 0.0088, left T = 4.66, p = 0.031). These peak voxels, which were affected by the variant, existed in the orbital region of the inferior frontal gyri. Individuals with the risk G/G genotype of rs7914558 had smaller GM volumes in the bilateral inferior frontal gyri than carriers of the non-risk A-allele. Although several effects of the genotype and the genotype-diagnosis interaction of other SNPs on GM volumes were observed in the exploratory VBM analyses, these effects did not remain after the FWE- correction for multiple tests (p > 0.05).ConclusionsOur findings suggest that the genetic variant in the CNNM2 gene could be implicated in the pathogenesis of schizophrenia through the GM volumetric vulnerability of the orbital regions in the inferior frontal gyri.

Dysbindin-1 and NRG-1 gene expression in immortalized lymphocytes from patients with schizophrenia

The dysbindin-1 and neuregulin-1 (NRG-1) genes are related to schizophrenia. Expression studies in postmortem brains have revealed lower expression of dysbindin-1 and higher expression of NRG-1 in brain tissue from subjects with schizophrenia. In addition to the difficulty of sampling, the use of postmortem brain tissues is not ideal because these tissues are heterogeneous with respect to biochemical parameters, lifetime history of medications and physiological status at the time of death. In contrast, medication and environmental influences that could mask the genetic basis of differences in RNA expression are removed in immortalized lymphocytes by culturing. Only a few microarray analysis studies using immortalized lymphocytes in schizophrenia have been reported, and whether immortalized lymphocytes are an appropriate alternative to neuronal tissue remains controversial. In this study, we measured the mRNA expression levels of dysbindin-1, NRG-1 and two other genes (NPY1R and GNAO1) in immortalized lymphocytes from 45 patients with schizophrenia and 45 controls using real-time quantitative reverse transcriptase-PCR. No difference was observed between patients and controls with respect to the expression of dysbindin-1, NRG-1, NPY1R or GNAO1 gene. Our findings suggest that the gene expression profile of immortalized lymphocyte from schizophrenic patients is different from that in postmortem brain tissue at least with respect to the dysbindin-1 and NRG-1 genes.

The SIGMAR1 gene is associated with a risk of schizophrenia and activation of the prefrontal cortex

Several studies have identified the possible involvement of sigma non-opioid intracellular receptor 1 (SIGMAR1) in the pathogenesis of schizophrenia. The Gln2Pro polymorphism in the SIGMAR1 gene has been extensively examined for an association with schizophrenia. However, findings across multiple studies have been inconsistent. We performed a meta-analysis of the association between the functional Gln2Pro polymorphism and schizophrenia using combined samples (1254 patients with schizophrenia and 1574 healthy controls) from previously published studies and our own additional samples (478 patients and 631 controls). We then used near-infrared spectroscopy to analyze the effects of the Gln2Pro genotype, a schizophrenia diagnosis and the interaction between genotype and diagnosis on activation of the prefrontal cortex (PFC) during a verbal fluency task (127 patients and 216 controls). The meta-analysis provided evidence of an association between Gln2Pro and schizophrenia without heterogeneity across studies (odds ratio=1.12, p=0.047). Consistent with previous studies, patients with schizophrenia showed lower bilateral activation of the PFC when compared to controls (p<0.05). We provide evidence that Pro carriers, who are more common among patients with schizophrenia, have significantly lower activation of the right PFC compared to subjects with the Gln/Gln genotype (p=0.013). These data suggest that the SIGMAR1 polymorphism is associated with an increased risk of schizophrenia and differential activation of the PFC.

Performance on the Wechsler Adult Intelligence Scale-III in Japanese patients with schizophrenia.

Patients with schizophrenia have been reported to perform worse than non‐schizophrenic populations on neuropsychological tests, which may be affected by cultural factors. The aim of this study was to examine the performance of a sizable number of patients with schizophrenia on the Japanese version of the Wechsler Adult Intelligence Scale‐III (WAIS‐III) compared with healthy controls.

Changes in plasma D-serine, L-serine, and glycine levels in treatment-resistant schizophrenia before and after clozapine treatment.

Hypofunction of the N-methyl-d-aspartate (NMDA) subtype of glutamate receptors may be involved in the pathophysiology of schizophrenia. Many studies have investigated peripheral NMDA receptor-related glutamatergic amino acid levels because of their potential as biological markers. Peripheral d-serine levels and the ratio of d-serine to total serine have been reported to be significantly lower in patients with schizophrenia than in controls. Peripheral d-serine levels and the d-/l-serine ratio have also been reported to significantly increase in patients with schizophrenia as their clinical symptoms improve from the time of admission to the time of discharge. In this study, we examined whether peripheral NMDA receptor-related glutamatergic amino acids levels were altered in patients with treatment-resistant schizophrenia compared to controls and whether these peripheral amino acids levels were altered by clozapine treatment. Twenty-two patients with treatment-resistant schizophrenia and 22 age- and gender-matched healthy controls were enrolled. The plasma levels of d-serine, l-serine, glycine, glutamate, and glutamine were measured before and after clozapine treatment. We found that the plasma levels of d-serine and the d-/l-serine ratio were significantly lower in the patients before clozapine treatment than in the controls. The d-/l-serine ratio was significantly increased by clozapine treatment in patients, and no significant difference was observed in the plasma levels of d-serine and the d-/l-serine ratio between the patients after clozapine treatment and the controls. We also found that plasma glycine levels and the glycine/l-serine ratio were significantly increased following clozapine treatment in the patients, and the glycine/l-serine ratio was significantly higher in the patients after clozapine treatment than in the controls. There was no significant difference in the plasma levels of glutamate and glutamine both between the controls and patients and between before and after clozapine treatment. This study firstly demonstrated changes of d-/l-serine and glycine/l-serine ratio between before and after clozapine treatment, suggesting that the plasma d-/l-serine ratio and glycine/l-serine ratio could be markers of therapeutic efficacy or clinical state in treatment-resistant schizophrenia.

Gene expression analysis in lymphoblasts derived from patients with autism spectrum disorder

BackgroundThe autism spectrum disorders (ASDs) are complex neurodevelopmental disorders that result in severe and pervasive impairment in the development of reciprocal social interaction and verbal and nonverbal communication skills. In addition, individuals with ASD have stereotypical behavior, interests and activities. Rare mutations of some genes, such as neuroligin (NLGN) 3/4, neurexin (NRXN) 1, SHANK3, MeCP2 and NHE9, have been reported to be associated with ASD. In the present study, we investigated whether alterations in mRNA expression levels of these genes could be found in lymphoblastoid cell lines derived from patients with ASD.MethodsWe measured mRNA expression levels of NLGN3/4, NRXN1, SHANK3, MeCP2, NHE9 and AKT1 in lymphoblastoid cells from 35 patients with ASD and 35 healthy controls, as well as from 45 patients with schizophrenia and 45 healthy controls, using real-time quantitative reverse transcriptase polymerase chain reaction assays.ResultsThe mRNA expression levels of NLGN3 and SHANK3 normalized by β-actin or TBP were significantly decreased in the individuals with ASD compared to controls, whereas no difference was found in the mRNA expression level of MeCP2, NHE9 or AKT1. However, normalized NLGN3 and SHANK3 gene expression levels were not altered in patients with schizophrenia, and expression levels of NLGN4 and NRXN1 mRNA were not quantitatively measurable in lymphoblastoid cells.ConclusionsOur results provide evidence that the NLGN3 and SHANK3 genes may be differentially expressed in lymphoblastoid cell lines from individuals with ASD compared to those from controls. These findings suggest the possibility that decreased mRNA expression levels of these genes might be involved in the pathophysiology of ASD in a substantial population of ASD patients.

Whole-exome sequencing and neurite outgrowth analysis in autism spectrum disorder

Autism spectrum disorder (ASD) is a complex group of clinically heterogeneous neurodevelopmental disorders with unclear etiology and pathogenesis. Genetic studies have identified numerous candidate genetic variants, including de novo mutated ASD-associated genes; however, the function of these de novo mutated genes remains unclear despite extensive bioinformatics resources. Accordingly, it is not easy to assign priorities to numerous candidate ASD-associated genes for further biological analysis. Here we developed a convenient system for identifying an experimental evidence-based annotation of candidate ASD-associated genes. We performed trio-based whole-exome sequencing in 30 sporadic cases of ASD and identified 37 genes with de novo single-nucleotide variations (SNVs). Among them, 5 of those 37 genes, POGZ, PLEKHA4, PCNX, PRKD2 and HERC1, have been previously reported as genes with de novo SNVs in ASD; and consultation with in silico databases showed that only HERC1 might be involved in neural function. To examine whether the identified gene products are involved in neural functions, we performed small hairpin RNA-based assays using neuroblastoma cell lines to assess neurite development. Knockdown of 8 out of the 14 examined genes significantly decreased neurite development (P<0.05, one-way analysis of variance), which was significantly higher than the number expected from gene ontology databases (P=0.010, Fishers exact test). Our screening system may be valuable for identifying the neural functions of candidate ASD-associated genes for further analysis and a substantial portion of these genes with de novo SNVs might have roles in neuronal systems, although further detailed analysis might eliminate false positive genes from identified candidate ASD genes.