Associations of histone deacetylase-2 and histone deacetylase-3 genes with schizophrenia in a Chinese population

Link between obsessive-compulsive disorder and polymorphisms in HDAC genes

Objective:

Recently, epigenetic mechanisms related to histone modifications including histone deacetylation (HDAC) have been emphasized in psychiatric diseases. Few studies have investigated the relationship of HDAC gene variations to psychiatric diseases, but these gene variations have never been studied in obsessive-compulsive disorder (OCD). The present case-control study aimed to compare symptomatology with HDAC gene variations in patients with OCD.

Methods:

Illumina next-generation sequencing of six HDAC genes (HDAC2,3,4,9,10,11) was performed on DNA samples isolated from 200 Turkish subjects recruited from routine clinical practice. Twenty-seven single nucleotide polymorphism (SNPs) in six HDAC genes were scanned with the LightSNiP method.

Results:

New variants, all previously unreported in the literature, were identified in the HDAC4, HDAC10, and HDAC11 genes. When control and OCD patient groups were compared, a statistically significant difference was found in HDAC2 rs13212283, HDAC4 rs1063639, and HDAC10 rs1555048 in terms of genotype distribution (p < 0.05). In addition, in the OCD group, a statistically significant relationship was found between some obsessions/compulsions and HDAC2, HDAC3, and HDAC4 polymorphisms (p < 0.05).

Conclusions:

Our study shows that the HDAC2, HDAC3, HDAC4, and HDAC10 genes may play a role in the pathogenesis of OCD.

Two-stage additional evidence support association of common variants in the HDAC3 with the increasing risk of schizophrenia susceptibility

Schizophrenia (SCZ) is a complex neuropsychiatric disorder with high heritability. Abnormal gene methylation was found to play a key role in the development of SCZ, suggesting that histone deacetylases (HDACs) may increase the expression of several key genes in the brain. However, recent studies evaluating the association between SCZ and genetic polymorphisms in histone deacetylase 3 (encoded by HDAC3) have shown conflicting results. In this study, we designed a two-stage case-control study to investigate the association of the HDAC3 with SCZ. Fourteen tag single nucleotide polymorphisms (SNPs) entirely covering the region of HDAC3 were analyzed in the testing group of 1,421 patients and 2,823 healthy controls, and the SNP rs14251 was found to be significant (and rs2530223 to be nominally significant). The significant result of rs14251 was successfully replicated in the validation group consisting of 896 cases and 1,815 healthy controls (P = 0.009276, OR = 1.219), and also confirmed by haplotype based analyses (rs976552-rs14251, global P < 0.001). To sum up, our results provide additional evidence that HDAC3 confers the increasing risk of SCZ susceptibility in Han Chinese individuals, suggesting this gene as a potential genetic modifier for SCZ development. © 2016 Wiley Periodicals, Inc.

Increased histone deacetylase activity in peripheral blood mononuclear cells of patients with schizophrenia

This study investigates the association between histone deacetylase (HDAC) activity in human peripheral blood mononuclear cells (PBMCs) and schizophrenia. Data were derived from a case-control association study of 19 unrelated adult patients with schizophrenia and 21 matched healthy controls. HDAC activity was measured with a HDAC activity colorimetric assay kit. Our findings suggest that HDAC activity in PBMCs is higher in patients with schizophrenia than in healthy people.

Transcriptome alterations of mitochondrial and coagulation function in schizophrenia by cortical sequencing analysis

Background

Transcriptome sequencing of brain samples provides detailed enrichment analysis of differential expression and genetic interactions for evaluation of mitochondrial and coagulation function of schizophrenia. It is implicated that schizophrenia genetic and protein interactions may give rise to biological dysfunction of energy metabolism and hemostasis. These findings may explain the biological mechanisms responsible for negative and withdraw symptoms of schizophrenia and antipsychotic-induced venous thromboembolism.

We conducted a comparison of schizophrenic candidate genes from literature reviews and constructed the schizophrenia-mediator network (SCZMN) which consists of schizophrenic candidate genes and associated mediator genes by applying differential expression analysis to BA22 RNA-Seq brain data. The network was searched against pathway databases such as PID, Reactome, HumanCyc, and Cell-Map. The candidate complexes were identified by MCL clustering using CORUM for potential pathogenesis of schizophrenia.

Results

Published BA22 RNA-Seq brain data of 9 schizophrenic patients and 9 controls samples were analyzed. The differentially expressed genes in the BA22 brain samples of schizophrenia are proposed as schizophrenia candidate marker genes (SCZCGs). The genetic interactions between mitochondrial genes and many under-expressed SCZCGs indicate the genetic predisposition of mitochondria dysfunction in schizophrenia. The biological functions of SCZCGs, as listed in the Pathway Interaction Database (PID), indicate that these genes have roles in DNA binding transcription factor, signal and cancer-related pathways, coagulation and cell cycle regulation and differentiation pathways.

In the query-query protein-protein interaction (QQPPI) network of SCZCGs, TP53, PRKACA, STAT3 and SP1 were identified as the central "hub" genes. Mitochondrial function was modulated by dopamine inhibition of respiratory complex I activity. The genetic interaction between mitochondria function and schizophrenia may be revealed by DRD2 linked to NDUFS7 through protein-protein interactions of FLNA and ARRB2.

The biological mechanism of signaling pathway of coagulation cascade was illustrated by the PPI network of the SCZCGs and the coagulation-associated genes. The relationship between antipsychotic target genes (DRD2/3 and HTR2A) and coagulation factor genes (F3, F7 and F10) appeared to cascade the following hemostatic process implicating the bottleneck of coagulation genetic network by the bridging of actin-binding protein (FLNA).

Conclusions

It is implicated that the energy metabolism and hemostatic process have important roles in the pathogenesis for schizophrenia. The cross-talk of genetic interaction by these co-expressed genes and reached candidate genes may address the key network in disease pathology. The accuracy of candidate genes evaluated from different quantification tools could be improved by crosstalk analysis of overlapping genes in genetic networks.

The epigenome and postnatal environmental influences in psychotic disorders

OBJECTIVES

Schizophrenia spectrum disorders and bipolar spectrum disorders are the product of both heritable and non-heritable factors, the impact of which converges at different biological levels. Recent evidence from molecular approaches has provided new insights about how environmental exposures cause persistent alterations in the regulation of gene expression, particularly by so-called epigenetic mechanisms. The aim of this review is to provide an overview of findings of epigenetic studies in psychotic disorders, summarizing findings of human and animal studies on epigenetic alterations due to postnatal environmental exposures associated with psychotic disorders.

METHODS

Electronic and manual literature search of MEDLINE, EMBASE and PSYCHINFO, using a range of search terms around epigenetics, DNA methylation, histone modifications, psychoses, schizophrenia, bipolar disorder and environmental risks associated with psychotic disorders as observed in human and experimental animal studies, complemented by review articles and cross-references.

RESULTS

Despite several promising findings of differential epigenetic profiles in individuals with psychotic disorders in the studies published to date, the knowledge of the role of epigenetic processes in psychotic disorder remains very limited, and should be interpreted cautiously given various challenges in this rapidly evolving field of research.

CONCLUSIONS

Integration of epigenetic findings into biopsychosocial models of the etiology of psychotic disorders eventually may yield important insights into the biological underpinnings of the onset and course of psychotic disorders.