A common genetic variant of the chromogranin A-derived peptide catestatin is associated with atherogenesis and hypertension in a Japanese population.

Chromogranin A (CHGA) is a major protein in the secretory granules of chromaffin cells. CHGA also gives rise to cardiovascular/metabolism regulatory peptides, such as catestatin (CST) and pancreastatin (PST). While CST is a potent inhibitor of catecholamine secretion, PST is a potent physiological inhibitor of glucose-induced insulin secretion. Recently, several SNPs were identified in the CST and PST domains of CHGA locus in different populations. Among the discovered SNPs, CST variant allele Ser-364 was associated with blood pressure alteration and PST variant allele Ser-297 was associated with significantly higher plasma glucose level. In this study, we examined whether these CST and PST variant alleles exist and influence cardiovascular and metabolic phenotypes in Japanese population. Our study comprised of 343 Japanese subjects aged 45-85 years (143 men and 200 women, mean age 66 ± 8 years). We determined the genotypes of CST and PST by PCR-direct sequencing method and carried out genotype-phenotype association analysis. In 343 participants, the minor allele frequency of CST variant Ser-364 was 6.10%. On the other hand, we did not detect the PST variant Ser-297 in this entire study population. The presence of Ser-364 allele was associated with increased in baPWV (an index of systemic arterial stiffness) that suggests an initiation and/or progression atherogenesis and hypertension. The Ser-364 allele was also associated with elevated systolic blood pressure and pulse pressure, consistent with increased baPWV. In conclusion, the CST Ser-364 allele may increase the risk for cardiovascular diseases in Japanese population.

Experimental evidence for the involvement of PDLIM5 in mood disorders in hetero knockout mice.

BACKGROUND: Reports indicate that PDLIM5 is involved in mood disorders. The PDLIM5 (PDZ and LIM domain 5) gene has been genetically associated with mood disorders; it's expression is upregulated in the postmortem brains of patients with bipolar disorder and downregulated in the peripheral lymphocytes of patients with major depression. Acute and chronic methamphetamine (METH) administration may model mania and the evolution of mania into psychotic mania or schizophrenia-like behavioral changes, respectively. METHODS: To address whether the downregulation of PDLIM5 protects against manic symptoms and cause susceptibility to depressive symptoms, we evaluated the effects of reduced Pdlim5 levels on acute and chronic METH-induced locomotor hyperactivity, prepulse inhibition, and forced swimming by using Pdlim5 hetero knockout (KO) mice. RESULTS: The homozygous KO of Pdlim5 is embryonic lethal. The effects of METH administration on locomotor hyperactivity and the impairment of prepulse inhibition were lower in Pdlim5 hetero KO mice than in wild-type mice. The transient inhibition of PDLIM5 (achieved by blocking the translocation of protein kinase C epsilon before the METH challenge) had a similar effect on behavior. Pdlim5 hetero KO mice showed increased immobility time in the forced swimming test, which was diminished after the chronic administration of imipramine. Chronic METH treatment increased, whereas chronic haloperidol treatment decreased, Pdlim5 mRNA levels in the prefrontal cortex. Imipramine increased Pdlim5 mRNA levels in the hippocampus. CONCLUSION: These findings are partially compatible with reported observations in humans, indicating that PDLIM5 is involved in psychiatric disorders, including mood disorders.

Phencyclidine-induced decrease of synaptic connectivity via inhibition of BDNF secretion in cultured cortical neurons.

Repeated administration of phencyclidine (PCP), a noncompetitive N-methyl-D-aspartate (NMDA) receptor blocker, produces schizophrenia-like behaviors in humans and rodents. Although impairment of synaptic function has been implicated in the effect of PCP, the molecular mechanisms have not yet been elucidated. Considering that brain-derived neurotrophic factor (BDNF) plays an important role in synaptic plasticity, we examined whether exposure to PCP leads to impaired BDNF function in cultured cortical neurons. We found that PCP caused a transient increase in the level of intracellular BDNF within 3 h. Despite the increased intracellular amount of BDNF, activation of Trk receptors and downstream signaling cascades, including MAPK/ERK1/2 and PI3K/Akt pathways, were decreased. The number of synaptic sites and expression of synaptic proteins were decreased 48 h after PCP application without any impact on cell viability. Both electrophysiological and biochemical analyses revealed that PCP diminished glutamatergic neurotransmission. Furthermore, we found that the secretion of BDNF from cortical neurons was suppressed by PCP. We also confirmed that PCP-caused downregulation of Trk signalings and synaptic proteins were restored by exogenous BDNF application. It is possible that impaired secretion of BDNF and subsequent decreases in Trk signaling are responsible for the loss of synaptic connections caused by PCP.

Further evidence for a male-selective genetic association of synapse-associated protein 97 (SAP97) gene with schizophrenia.

BACKGROUND: The synapse-associated protein 97 gene (SAP97) encodes a regulatory scaffold protein for the localization of L-alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA), kainate and N-methyl-D-aspartate (NMDA) type glutamate receptors. We have recently demonstrated nominally significant associations between SAP97 gene and schizophrenia among Japanese males. The present study aimed to replicate these findings using an independent and larger sample. METHODS: We investigated seven SAP97 single nucleotide polymorphisms (SNPs) that displayed a significant association with schizophrenia in our preceding study in an independent Japanese population consisting of a total of 393 unrelated patients with schizophrenia (232 males and 161 females) and 393 unrelated control subjects (211 males and 182 females). RESULTS: The SNP rs9843659 showed a significant genotypic association with male patients in a recessive model (p = 0.037). The analysis of the combined data from the current and prior studies also demonstrated a significant association of this SNP (p = 0.0039). The meta-analysis for the allele frequency covering the two studies yielded an odds ratio of 1.38. CONCLUSIONS: The present study replicated the previously reported male-selective genetic association between the SAP97 polymorphism and schizophrenia. These findings further support the possible involvement of the SAP97 gene variation in the susceptibility to schizophrenia in males and in the genetic basis for sex differences in the disorder.

Association of SNPs linked to increased expression of SLC1A1 with schizophrenia.

Glutamate is one of the key molecules involved in signal transduction in the brain, and dysfunction of glutamate signaling could be linked to schizophrenia. The SLC1A1 gene located at 9p24 encodes the glutamate transporter EAAT3/EAAC1. To investigate the association between the SLC1A1 gene and schizophrenia in the Japanese population, we genotyped 19 tagging single nucleotide polymorphisms (tagSNPs) in the SLC1A1 gene in 576 unrelated individuals with schizophrenia and 576 control subjects followed by replication in an independent case-control study of 1,344 individuals with schizophrenia and 1,344 control subjects. In addition, we determined the boundaries of the copy number variation (CNV) region in the first intron (Database of Genomic Variants, chr9:4516796-4520549) and directly genotyped the CNV because of significant deviation from the Hardy-Weinberg equilibrium. The CNV was not associated with schizophrenia. Four SNPs showed a possible association with schizophrenia in the screening subjects and the associations were replicated in the same direction (nominal allelic P < 0.05), and, among them, an association with rs7022369 was replicated even after Bonferroni correction (allelic nominal P = 5 × 10(-5) , allelic corrected P = 2.5 × 10(-4) , allelic odds ratio, 1.30; 95% CI: 1.14-1.47 in the combined subjects). Expression analysis quantified by the real-time quantitative polymerase chain reaction in the postmortem prefrontal cortex of 43 Japanese individuals with schizophrenia and 11 Japanese control subjects revealed increased SLC1A1 expression levels in individuals homozygous for the rs7022369 risk allele (P = 0.003). Our findings suggest the involvement of SLC1A1 in the pathogenesis of schizophrenia.

Possible association between interleukin-1ß gene and schizophrenia in a Japanese population.

BACKGROUND: Several lines of evidence have implicated the pro-inflammatory cytokine interleukin-1beta (IL-1ß) in the etiology of schizophrenia. Although a number of genetic association studies have been reported, very few have systematically examined gene-wide tagging polymorphisms. METHODS: A total of 533 patients with schizophrenia (302 males: mean age ± standard deviation 43.4 ± 13.0 years; 233 females; mean age 44.8 ± 15.3 years) and 1136 healthy controls (388 males: mean age 44.6 ± 17.3 years; 748 females; 46.3 ± 15.6 years) were recruited for this study. All subjects were biologically unrelated Japanese individuals. Five tagging polymorphisms of IL-1ß gene (rs2853550, rs1143634, rs1143633, rs1143630, rs16944) were examined for association with schizophrenia. RESULTS: Significant difference in allele distribution was found between patients with schizophrenia and controls for rs1143633 (P = 0.0089). When the analysis was performed separately in each gender, significant difference between patients and controls in allele distribution of rs1143633 was observed in females (P = 0.0073). A trend towards association was also found between rs16944 and female patients with schizophrenia (P = 0.032). CONCLUSIONS: The present study shows the first evidence that the IL-1ß gene polymorphism rs1143633 is associated with schizophrenia susceptibility in a Japanese population. The results suggest the possibility that the influence of IL-1ß gene variations on susceptibility to schizophrenia may be greater in females than in males. Findings of the present study provide further support for the role of IL-1ß in the etiology of schizophrenia.

Modulation of cortisol responses to the DEX/CRH test by polymorphisms of the interleukin-1beta gene in healthy adults.

BACKGROUND: Recently, hypothalamus-pituitary-adrenal (HPA) axis function assessed with the combined dexamethasone (DEX)/corticotropin releasing hormone (CRH) test has been shown to be associated with response to antidepressant treatment. A polymorphism (rs16944) in the interleukin-1beta (IL-1ß) gene has also been reported to be associated with the medication response in depression. These findings prompted us to examine the possible association between IL-1ß gene polymorphisms and HPA axis function assessed with the DEX/CRH test. METHODS: DEX/CRH test was performed in 179 healthy volunteers (45 males: mean age 40.5 ± 15.8 years; 134 females: mean age 47.1 ± 13.2 years). Five tagging single nucleotide polymorphisms (SNPs) of IL-1ß gene (rs2853550, rs1143634, rs1143633, rs1143630, rs16944) were selected at an r2 threshold of 0.80 with a minor allele frequency > 0.1. Genotyping was performed by the TaqMan allelic discrimination assay. A two-way factorial analysis of variance (ANOVA) was performed with the DEX/CRH test results as the dependent variable and genotype and gender as independent variables. To account for multiple testing, P values < 0.01 were considered statistically significant for associations between the genotypes and the cortisol levels. RESULTS: The cortisol levels after DEX administration (DST-Cortisol) showed significant associations with the genotypes of rs16944 (P = 0.00049) and rs1143633 (P = 0.0060), with no significant gender effect or genotype × gender interaction. On the other hand, cortisol levels after CRH administration (DEX/CRH-Cortisol) were affected by gender but were not significantly influenced by the genotype of the examined SNPs, with no significant genotype × gender interaction. CONCLUSIONS: Our results suggest that genetic variations in the IL-1ß gene contribute to the HPA axis alteration assessed by DST-Cortisol in healthy subjects. On the other hand, no significant associations of the IL-1ß gene polymorphisms with the DEX/CRH-Cortisol were observed. Confirmation of our findings in futures studies may add new insight into the communication between the immune system and the HPA axis.

Development of electroluminescence based pressure-sensitive paint system.

We introduce a pressure-sensitive paint (PSP) measurement system based on an electroluminescence (EL) as a surface illumination. This consists of an inorganic EL as the illumination, a short-pass filter, and a platinum-porphyrin based PSP. The short-pass filter, which passes below 500 nm, was used to separate an overlay of the EL illumination and the PSP emission. The EL shows an opposite temperature dependency to that of the PSP. It gives a uniform illumination compared to that of a point illumination source such as a xenon lamp. Under atmospheric conditions, the resultant EL-PSP system reduces the temperature dependency by 54% compared to that of a conventional PSP system. An application of the EL-PSP system to a sonic jet impingement shows that the system demonstrated its reduction of the temperature dependency by 75% in a pressure measurement and reduces an image misalignment error.

Prednisolone causes anxiety- and depression-like behaviors and altered expression of apoptotic genes in mice hippocampus.

Glucocorticoids are known to cause psychiatric disorders including depression. Prednisolone (PSL) is one of the most widely used synthetic glucocorticoids to treat various medical diseases; however, little is known about PSL-induced behavioral changes and its molecular basis in the brain. Growing evidence has implicated that hippocampal remodeling or damage play a role in the pathogenic effect of glucocorticoids. In this study, mice were administered PSL (50 or 100mg/kg) or vehicle for 6 or 7 days and subjected to a series of behavioral tests, i.e., open field, elevated plus maze, prepulse inhibition, forced swim, and tail suspension tests. Hippocampal tissues were subject to microarray analysis using the GeneChip Mouse Genome 430 2.0 Array (Affymetrix) containing 45,101 probes of transcripts. Increased anxiety- and depression-like behaviors assessed with open field, elevated plus maze, and tail suspension tests were observed. Microarray analysis detected 108 transcripts with a fold change of >2.0 or <0.5 in which many cell-death-related genes were found. The microarray data was validated by quantitative reverse transcriptase-polymerase chain reaction analysis. Our results demonstrated that PSL causes anxiety- and depression-like behaviors, and suggest that altered gene expressions related to hippocampal remodeling or damage are involved in the effect of PSL on such behaviors.

Preliminary genome-wide association study of bipolar disorder in the Japanese population.

Recent progress in genotyping technology and the development of public databases has enabled large-scale genome-wide association tests with diseases. We performed a two-stage genome-wide association study (GWAS) of bipolar disorder (BD) in Japanese cohorts. First we used Affymetrix 100K GeneChip arrays in the analysis of 107 cases with bipolar I disorder and 107 controls, and selected markers that were nominally significant (P < 0.01) in at least one of the three models (1,577 markers in total). In the follow-up stage, we analyzed these markers using an Illumina platform (1,526 markers; 51 markers were not designable for the platform) and an independent sample set, which consisted of 395 cases (bipolar I + II) and 409 controls. We also assessed the population stratification of current samples using principal components analysis. After the two-stage analysis, 89 markers remained nominally significant (allelic P < 0.05) with the same allele being consistently over-represented in both the first and the follow-up stages. However, none of these were significant after correction for multiple-testing by false discovery rates. Sample stratification was virtually negligible. Collectively, this is the first GWAS of BD in the Japanese population. But given the small sample size and the limited genomic coverage, these results should be taken as preliminary.

Failure to confirm an association between Epsin 4 and schizophrenia in a Japanese population.

Previous studies suggested that genetic variations in the 5' region of Epsin 4, a gene encoding enthoprotin on chromosome 5q33, are associated with schizophrenia. However, conflicting results have also been reported. We examined the possible association in a Japanese sample of 354 patients and 365 controls. Seventeen polymorphisms of Epsin 4 [3 microsatellites and 14 single nucleotide polymorphisms (SNPs)] were selected. A microsatellite marker (D5S1403) demonstrated a significant difference in the allele frequency between patients and controls (uncorrected P = 0.04). However, there was no significant difference in the genotype or allele frequency between the two groups for the other microsatellites or SNPs. Haplotype-based analysis provided no evidence for an association. The positive result at D5S1403 no longer reached statistical significance when multiple testing was taken into consideration. Our results suggest that the examined region of Epsin 4 does not have a major influence on susceptibility to schizophrenia in Japanese.

Genetic variations of human neuropsin gene and psychiatric disorders: polymorphism screening and possible association with bipolar disorder and cognitive functions.

Human neuropsin (NP) (hNP) has been implicated in the progressive change of cognitive abilities during primate evolution. The hNP gene maps to chromosome 19q13, a region reportedly linked to schizophrenia and bipolar disorder. Therefore, hNP is a functional and positional candidate gene for association with schizophrenia, mood disorders, and cognitive ability. Polymorphism screening was performed for the entire hNP gene. The core promoter region was determined and whether or not transcriptional activity alters in an allele-dependent manner was examined by using the dual-luciferase system. Allelic and genotypic distributions of five single-nucleotide polymorphisms (SNPs) were compared between patients with schizophrenia (n=439), major depression (n=409), bipolar disorder (n=207), and controls (n=727). A possible association of the hNP genotype with memory index (assessed with Wechsler Memory Scale, revised, WMS-R) and intelligence quotient (IQ assessed with Wechsler Adult Intelligence Scale, revised; WAIS-R) was examined in healthy controls (n=166). A total of 28 SNPs, including nine novel SNPs, were identified. No significant effects on transcriptional activity were observed for SNPs in the promoter region. A significant allelic association was found between several SNPs and bipolar disorder (for SNP23 at the 3' regulatory region; odds ratio 1.48, 95% confidential interval 1.16-1.88, P=0.0015). However, such an association was not detected for schizophrenia or depression. Significant differences were observed between SNP23 and attention/concentration sub-scale score of WMS-R (P=0.016) and verbal IQ (P<0.001). Genetic variation of the hNP gene may contribute to molecular mechanisms of bipolar disorder and some aspects of memory and intelligence.

Failure to confirm an association between the PLXNA2 gene and schizophrenia in a Japanese population.

Plexins are receptors for multiple classes of semaphorins, either alone or in combination with neuropilins. Plexins participate in many cellular events that include axonal repulsion, axonal attraction, cell migration, axon pruning, and synaptic plasticity. PLXNA2 maps to chromosome 1q32. Several linkage studies reported schizophrenia susceptibility loci in the 1q22-42 region. A recent study reported that intronic single nucleotide polymorphisms (SNPs) of PLXNA2 were associated with schizophrenia in a European American population. We attempted to replicate this finding in a Japanese sample of 336 patients with schizophrenia and 304 controls. In addition, we examined 3 non-synonymous SNPs (Arg5Gln, GLn57Arg, and Ala267Thr) in PLXNA2. Genotyping was performed by the TaqMan allelic discrimination assay. There was no significant difference in genotype or allele distribution of either the 4 intronic SNPs or the 3 non-synonymous SNPs between patients and controls. Furthermore, haplotype-based analyses did not provide evidence for an association. These results suggest that PLXNA2 may not play a major role in the development of schizophrenia in our Japanese sample.

Gene-gene interaction analysis of personality traits in a Japanese population using an electrochemical DNA array chip analysis.

It has been suggested that genes involved in the central dopaminergic pathway may contribute to personality traits. However, the results of association studies for these genes have not been consistent. The present study investigated the relationship between the specific polymorphisms of MAO-A, COMT, DRD2, DRD3 and personality traits in Japanese women using a novel genotyping method involving electrochemical DNA array (ECA) chip analysis. Single marker association analysis for each mutation revealed no significant association between scores for Neuroticism Extraversion Openness-Five Factor Inventory (NEO-FFI) items. Gene-gene interaction analysis showed that a MAO-A 30-bp repeatxCOMT (Val158Met)xDRD3 (Ser9Gly) had a marginally significant association with Agreeableness (P=0.0547). The present results suggest that a combination of polymorphisms of MAO-A, COMT, and DRD3 might affect personality traits in Japanese women.

A promoter haplotype of the inositol monophosphatase 2 gene (IMPA2) at 18p11.2 confers a possible risk for bipolar disorder by enhancing transcription.

Lithium is an effective mood stabilizer for bipolar disorder patients and its therapeutic effect may involve inhibition of inositol monophosphatase activity. In humans, the enzyme is encoded by two genes, IMPA1 and IMPA2. IMPA2 maps to 18p11.2, a genomic interval for which evidence of linkage to bipolar disorder has been supported by several reports. We performed a genetic association study in Japanese cohorts (496 patients with bipolar disorder and 543 control subjects). Interestingly, we observed association of IMPA2 promoter single nucleotide polymorphisms (SNPs) (-461C and -207T) with bipolar disorder, the identical SNPs reported previously in a different population. In vitro promoter assay and genetic haplotype analysis showed that the combination of (-461C)-(-207T)-(-185A) drove enhanced transcription and the haplotypes containing (-461C)-(-207T)-(-185A) contributed to risk for bipolar disorder. Expression study on post-mortem brains revealed increased transcription from the IMPA2 allele that harbored (-461C)-(-207T)-(-185A) in the frontal cortex of bipolar disorder patients. The examination of allele-specific expressions in post-mortem brains did not support genomic imprinting of IMPA2, which was suggested nearby genomic locus. Contrasting to a prior report, therapeutic concentrations of lithium could not suppress the transcription of IMPA2 mRNA, and the mood-stabilizing effect of lithium is, if IMPA2 was one of the targets of lithium, deemed to be generated via inhibition of enzymatic reaction rather than transcriptional suppression. In conclusion, the present study suggests that a promoter haplotype of IMPA2 possibly contributes to risk for bipolar disorder by elevating IMPA2 levels in the brain, albeit the genetic effect varies among populations.

Association study of the vesicular monoamine transporter 1 (VMAT1) gene with schizophrenia in a Japanese population.

BACKGROUND: Vesicular monoamine transporters (VMATs) mediate accumulation of monoamines such as serotonin, dopamine, adrenaline, and noradrenaline from the cytoplasm into storage organelles. The VMAT1 (alternatively solute carrier family 18: SLC18A1) regulates such biogenic amines in neuroendocrine systems. The VMAT1 gene maps to chromosome 8p21.3, a locus with strong evidence of linkage with schizophrenia. A recent study reported that a non-synonymous single nucleotide polymorphism (SNP) of the gene (Pro4Thr) was associated with schizophrenia. METHODS: We attempted to replicate this finding in a Japanese sample of 354 schizophrenics and 365 controls. In addition, we examined 3 other non-synonymous SNPs (Thr98Ser, Thr136Ile, and Val392Leu). Genotyping was performed by the TaqMan allelic discrimination assay. RESULTS: There was no significant difference in genotype or allele distribution of the three SNPs of Pro4Thr, Thr136Ile, or Val392Leu between patients and controls. There was, however, a significant difference in genotype and allele distributions for the Thr98Ser polymorphism between the two groups (P = 0.01 for genotype and allele). When sexes were examined separately, significant differences were observed in females (P = 0.006 for genotype, P = 0.003 for allele), but not in males. The Thr98 allele was more common in female patients than in female controls (odds ratio 1.69, 95% CI 1.19-2.40, P = 0.003). Haplotype-based analyses also provided evidence for a significant association in females. CONCLUSION: We failed to replicate the previously reported association of Pro4Thr of the VMAT1 gene with schizophrenia. However, we obtained evidence for a possible role of the Thr98Ser in giving susceptibility to schizophrenia in women.

Mitochondrial DNA 3644T-->C mutation associated with bipolar disorder.

Mitochondrial dysfunction associated with mutant mitochondrial DNA (mtDNA) has been suggested in bipolar disorder, and comorbidity with neurodegenerative diseases was often noted. We examined the entire sequence of mtDNA in six subjects with bipolar disorder having comorbid somatic symptoms suggestive of mitochondrial disorders and found several uncharacterized homoplasmic nonsynonymous nucleotide substitutions of mtDNA. Of these, 3644C was found in 5 of 199 patients with bipolar disorder but in none of 258 controls (p = 0.015). The association was significant in the extended samples [bipolar disorder, 9/630 (1.43%); controls, 1/734 (0.14%); p = 0.007]. On the other hand, only 5 of 25 family members with this mutation developed bipolar disorder, of which 4 patients with 3644C had comorbid physical symptoms. The 3644T-->C mutation converts amino acid 113, valine, to alanine in the NADH-ubiquinone dehydrogenase subunit I, a subunit of complex I, and 113 valine is well conserved from Drosophila to 61 mammalian species. Using transmitochondrial cybrids, 3644T-->C was shown to decrease mitochondrial membrane potential and complex I activity compared with haplogroup-matched controls. According to human mitochondrial genome polymorphism databases, 3644C was not found in centenarians but was found in 3% of patients with Alzheimer disease and 2% with Parkinson disease. The result of modest functional impairment caused by 3644T-->C suggests that this mutation could increase the risk for bipolar disorder.

No association between the Val66Met polymorphism of the brain-derived neurotrophic factor gene and bipolar disorder in a Japanese population: a multicenter study.

BACKGROUND: Two previous studies reported a significant association between a missense polymorphism (Val66Met) in the brain-derived neurotrophic factor (BDNF) gene and bipolar disorder; however, contradictory negative results have also been reported, necessitating further investigation. METHODS: We organized a multicenter study of a relatively large sample of 519 patients with bipolar disorder (according to DSM-IV criteria) and 588 control subjects matched for gender, age, and ethnicity (Japanese). Genotyping was done by polymerase chain reaction-based restriction fragment length polymorphism or direct sequencing. RESULTS: The genotype distributions and allele frequencies were similar among the patients and control subjects. Even if the possible relationships of the polymorphism with several clinical variables (i.e., bipolar I or II, presence of psychotic features, family history, and age of onset) were examined, no variable was related to the polymorphism. CONCLUSIONS: The Val66Met polymorphism of the BDNF gene is unrelated to the development or clinical features of bipolar disorder, at least in a Japanese population.