Haplotypes of the D-Amino Acid Oxidase Gene Are Significantly Associated with Schizophrenia and Its Neurocognitive Deficits.

D-amino acid oxidase (DAO) has been reported to be associated with schizophrenia. This study aimed to search for genetic variants associated with this gene. The genomic regions of all exons, highly conserved regions of introns, and promoters of this gene were sequenced. Potentially meaningful single-nucleotide polymorphisms (SNPs) obtained from direct sequencing were selected for genotyping in 600 controls and 912 patients with schizophrenia and in a replicated sample consisting of 388 patients with schizophrenia. Genetic associations were examined using single-locus and haplotype association analyses. In single-locus analyses, the frequency of the C allele of a novel SNP rs55944529 located at intron 8 was found to be significantly higher in the original large patient sample (p = 0.016). This allele was associated with a higher level of DAO mRNA expression in the Epstein-Barr virus-transformed lymphocytes. The haplotype distribution of a haplotype block composed of rs11114083-rs2070586-rs2070587-rs55944529 across intron 1 and intron 8 was significantly different between the patients and controls and the haplotype frequencies of AAGC were significantly higher in patients, in both the original (corrected p < 0.0001) and replicated samples (corrected p = 0.0003). The CGTC haplotype was specifically associated with the subgroup with deficits in sustained attention and executive function and the AAGC haplotype was associated with the subgroup without such deficits. The DAO gene was a susceptibility gene for schizophrenia and the genomic region between intron 1 and intron 8 may harbor functional genetic variants, which may influence the mRNA expression of DAO and neurocognitive functions in schizophrenia.

MicroRNA expression aberration as potential peripheral blood biomarkers for schizophrenia.

Since brain tissue is not readily accessible, a new focus in search of biomarkers for schizophrenia is blood-based expression profiling of non-protein coding genes such as microRNAs (miRNAs), which regulate gene expression by inhibiting the translation of messenger RNAs. This study aimed to identify potential miRNA signature for schizophrenia by comparing genome-wide miRNA expression profiles in patients with schizophrenia vs. healthy controls. A genome-wide miRNA expression profiling was performed using a Taqman array of 365 human miRNAs in the mononuclear leukocytes of a learning set of 30 cases and 30 controls. The discriminating performance of potential biomarkers was validated in an independent testing set of 60 cases and 30 controls. The expression levels of the miRNA signature were then evaluated for their correlation with the patients' clinical symptoms, neurocognitive performances, and neurophysiological functions. A seven-miRNA signature (hsa-miR-34a, miR-449a, miR-564, miR-432, miR-548d, miR-572 and miR-652) was derived from a supervised classification with internal cross-validation, with an area under the curve (AUC) of receiver operating characteristics of 93%. The putative signature was then validated in the testing set, with an AUC of 85%. Among these miRNAs, miR-34a was differentially expressed between cases and controls in both the learning (P = 0.005) and the testing set (P = 0.002). These miRNAs were differentially correlated with patients' negative symptoms, neurocognitive performance scores, and event-related potentials. The results indicated that the mononuclear leukocyte-based miRNA profiling is a feasible way to identify biomarkers for schizophrenia, and the seven-miRNA signature warrants further investigation.

ANXA7, PPP3CB, DNAJC9, and ZMYND17 genes at chromosome 10q22 associated with the subgroup of schizophrenia with deficits in attention and executive function.

BACKGROUND: A genome scan of Taiwanese schizophrenia families suggested linkage to chromosome 10q22.3. We aimed to find the candidate genes in this region. METHODS: A total of 476 schizophrenia families were included. Hierarchical clustering method was used for clustering families to homogeneous subgroups according to their performances of sustained attention and executive function. Association analysis was performed using family-based association testing and TRANSMIT. Candidate associated regions were identified using the longest significance run method. The relative messenger RNA expression level was determined using real-time reverse transcriptase polymerase chain reaction. RESULTS: First, we genotyped 18 microsatellite markers between D10S1432 and D10S1239. The maximum nonparametric linkage score was 2.79 on D10S195. Through family clustering, we found the maximum nonparametric linkage score was 3.70 on D10S195 in the family cluster with deficits in attention and executive function. Second, we genotyped 79 single nucleotide polymorphisms between D10S1432 and D10S580 in 90 attention deficit and execution deficit families. Association analysis indicated significant transmission distortion for nine single nucleotide polymorphisms. Using the longest significance run method, we identified a 427-kilobase region as a significant candidate region, which encompasses nine genes. Third, we studied messenger RNA expression of these nine genes in Epstein-Barr virus-transformed lymphoblastic cells. In schizophrenic patients, there was significantly lower expression of ANXA7, PPP3CB, and DNAJC9 and significantly higher expression of ZMYND17. CONCLUSIONS: ANXA7, PPP3CB, DNAJC9, and ZMYND17 genes are potential candidate genes for schizophrenia, especially in patients with deficits in sustained attention and executive function. The responsible functional variants remained to be clarified.

Genetic copy number variants in sib pairs both affected with schizophrenia.

BACKGROUND: Schizophrenia is a complex disorder with involvement of multiple genes. METHODS: In this study, genome-wide screening for DNA copy-number variations (CNVs) was conducted for ten pairs, a total of 20 cases, of affected siblings using oligonucleotide array-based CGH. RESULTS: We found negative symptoms were significantly more severe (p < 0.05) in the subgroup that harbored more genetic imbalance (n >== 13, n = number of CNV-disrupted genes) as compared with the subgroup with fewer CNVs (n <== 6), indicating that the degree of genetic imbalance may influence the severity of the negative symptoms of schizophrenia. Four central nervous system (CNS) related genes including CCAAT/enhancer binding protein, delta (CEBPD, 8q11.21), retinoid x receptor, alpha (RXRA, 9q34.2), LIM homeobox protein 5 (LHX5, 12q24.13) and serine/threonine kinase 11 (STK11, 19p13.3) are recurrently (incidence >== 16.7%) disrupted by CNVs. Two genes, PVR (poliovirus receptor) and BU678720, are concordantly deleted in one and two, respectively, pairs of co-affected siblings. However, we did not find a significant association of this BU678720 deletion and schizophrenia in a large case-control sample. CONCLUSIONS: We conclude that the high genetic loading of CNVs may be the underlying cause of negative symptoms of schizophrenia, and the CNS-related genes revealed by this study warrant further investigation.

Overexpression of heme oxygenase-1 protects dopaminergic neurons against 1-methyl-4-phenylpyridinium-induced neurotoxicity.

Heme oxygenase-1 (HO-1) is up-regulated in response to oxidative stress and catalyzes the degradation of pro-oxidant heme to carbon monoxide (CO), iron, and bilirubin. Intense HO-1 immunostaining in the Parkinsonian brain is demonstrated, indicating that HO-1 may be involved in the pathogenesis of Parkinsonism. We here locally injected adenovirus containing human HO-1 gene (Ad-HO-1) into rat substantia nigra concomitantly with 1-methyl-4-phenylpyridinium (MPP(+)). Seven days after injection of MPP(+) and Ad-HO-1, the brain was isolated for immunostaining and for measurement of dopamine content and inflammatory cytokines. It was found that overexpression of HO-1 significantly increased the survival rate of dopaminergic neurons; reduced the production of tumor necrosis factor alpha (TNF-alpha) and interleukin-1beta (IL-1beta) in substantia nigra; antagonized the reduction of striatal dopamine content induced by MPP(+); and also up-regulated brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) expression in substantia nigra. Apomorphine-induced rotation after MPP(+) treatment was also inhibited by Ad-HO-1. On the other hand, inhibition of HO enzymatic activity by zinc protoporphyrin-IX facilitated the MPP(+)-induced rotatory behavior and enhanced the reduction of dopamine content. HO-1 overexpression also protected dopaminergic neurons against MPP(+)-induced neurotoxicity in midbrain neuron-glia cocultures. Overexpression of HO-1 increased the expression of BDNF and GDNF in astrocytes and BDNF in neurons. Our results indicate that HO-1 induction exerts neuroprotection both in vitro and in vivo. Pharmacological or genetic approaches targeting HO-1 may represent a promising and novel therapeutic strategy in treating Parkinsonism.

SV40 T/t-common polypeptide specifically induces apoptosis in human cancer cells that overexpress HER2/neu.

Previously, we reported that SV40 T/t-common polypeptide, which contains the NH(2)-terminal common domain of SV40 large T and small t antigens, can repress HER2/neu (also known as erbB-2) expression and consequently suppress the tumorigenic potential of the HER2/neu-overexpressing ovarian carcinoma cells. Here we report that T/t-common could specifically induce apoptosis in HER2/neu-overexpressing human cancer cell lines but not in nontransformed cell lines and HER2/neu low-expressing human cancer cell lines. The ability of T/t-common to induce apoptosis in HER2/neu-overexpressing cancer cells was derived from its ability to inhibit HER2/neu because reexpression of a large amount of HER2/neu could block apoptosis induced by T/t-common. T/t-common expression in HER2/neu-overexpressing SK-OV-3 cancer cells led to down-regulation of Bcl-2 and Bcl-X(L), and overexpression of Bcl-2 could inhibit the ability of T/t-common to induce apoptosis in these cells. Therefore, the apoptosis-inducing activity of T/t-common is related to its ability to inhibit Bcl-2 expression in HER2/neu-overexpressing cancer cells. Consistent with the apoptosis-inducing activity of T/t-common, we found that T/t-common could specifically inhibit the soft-agarose colony-forming ability of the HER2/neu-overexpressing human cancer cell lines but not that of the HER2/neu low-expressing human cancer cell lines. Finally, we showed that T/t-common could specifically sensitize HER2/neu-overexpressing human cancer cell lines, but not HER2/neu low-expressing human cancer cell lines, to chemotherapeutic agent etoposide. Together, these data suggest that T/t-common alone or in combination with chemotherapy may provide a new approach for treatment of cancers that overexpress HER2/neu.

The hydrophobic heptad repeat in Region III of Escherichia coli transcription factor sigma 54 is essential for core RNA polymerase binding.

Escherichia coli transcription factor sigma 54 contains motifs that resemble closely those used for RNA polymerase II in mammalian cells, including two hydrophobic heptad repeats, a very acidic region and a glutamine-rich region. Triple changes in hydrophobic or multiple changes in acidic residues in Region III are known to severely impair core-binding ability. To investigate whether all the changes in triple mutants are necessary for core binding, site-directed mutagenesis was performed to create single and double mutants in the leucine or isoleucine residues in the heptad repeat in Region III. Single mutants showed no discernible loss of function. Double mutants showed partial protection of the -12 promoter element of the glnAp2 promoter due to the partial loss of their ability to bind core RNA polymerase. These mutations were deleterious to the function of sigma 54, which retained only 30-40% of wild-type mRNA levels. However, double mutants retained nearly normal ability to form open complexes. Two triple mutants created during previous work lost most, if not all, of their ability to bind core RNA polymerase, to protect the -12 promoter element of the glnAp2 promoter and to open the transcription start site. The two triple mutants produced about 20% or less than 10% of the wild-type transcripts from the glnAp2 promoter. These results demonstrate that the hydrophobic heptad repeat in Region III is essential for core RNA polymerase binding. Progressive loss of hydrophobicity of the hydrophobic heptad repeat in Region III of sigma 54 resulted in a progressive loss of core-binding ability, leading to the loss of -12 promoter element recognition and mRNA production.