Family-based association study of common variants, rare mutation study and epistatic interaction detection in HDAC genes in schizophrenia

Expression of the schizophrenia associated gene FEZ1 in the early developing fetal human forebrain

Introduction

The protein fasciculation and elongation zeta-1 (FEZ1) is involved in axon outgrowth but potentially interacts with various proteins with roles ranging from intracellular transport to transcription regulation. Gene association and other studies have identified FEZ1 as being directly, or indirectly, implicated in schizophrenia susceptibility. To explore potential roles in normal early human forebrain neurodevelopment, we mapped FEZ1 expression by region and cell type.

Methods

All tissues were provided with maternal consent and ethical approval by the Human Developmental Biology Resource. RNAseq data were obtained from previously published sources. Thin paraffin sections from 8 to 21 post-conceptional weeks (PCW) samples were used for RNAScope in situ hybridization and immunohistochemistry against FEZ1 mRNA and protein, and other marker proteins.

Results

Tissue RNAseq revealed that FEZ1 is highly expressed in the human cerebral cortex between 7.5-17 PCW and single cell RNAseq at 17-18 PCW confirmed its expression in all neuroectoderm derived cells. The highest levels were found in more mature glutamatergic neurons, the lowest in GABAergic neurons and dividing progenitors. In the thalamus, single cell RNAseq similarly confirmed expression in multiple cell types. In cerebral cortex sections at 8-10 PCW, strong expression of mRNA and protein appeared confined to post-mitotic neurons, with low expression seen in progenitor zones. Protein expression was observed in some axon tracts by 16-19 PCW. However, in sub-cortical regions, FEZ1 was highly expressed in progenitor zones at early developmental stages, showing lower expression in post-mitotic cells.

Discussion

FEZ1 has different expression patterns and potentially diverse functions in discrete forebrain regions during prenatal human development.

Epigenetic Targets in Schizophrenia Development and Therapy

Schizophrenia is regarded as a neurodevelopmental disorder with its course progressing throughout life. However, the aetiology and development of schizophrenia are still under investigation. Several data suggest that the dysfunction of epigenetic mechanisms is known to be involved in the pathomechanism of this mental disorder. The present article revised the epigenetic background of schizophrenia based on the data available in online databases (PubMed, Scopus). This paper focused on the role of epigenetic regulation, such as DNA methylation, histone modifications, and interference of non-coding RNAs, in schizophrenia development. The article also reviewed the available data related to epigenetic regulation that may modify the severity of the disease as a possible target for schizophrenia pharmacotherapy. Moreover, the effects of antipsychotics on epigenetic malfunction in schizophrenia are discussed based on preclinical and clinical results. The obtainable data suggest alterations of epigenetic regulation in schizophrenia. Moreover, they also showed the important role of epigenetic modifications in antipsychotic action. There is a need for more data to establish the role of epigenetic mechanisms in schizophrenia therapy. It would be of special interest to find and develop new targets for schizophrenia therapy because patients with schizophrenia could show little or no response to current pharmacotherapy and have treatment-resistant schizophrenia.

Time course of epigenetic modulation in response to concurrent exercise training in patients with schizophrenia

This study aimed to investigate the short and long-term effects of concurrent exercise training on anthropometric variables, HDCA2 activity and cortisol levels of individuals with schizophrenia (SZ). Therefore, 10 patients were submitted to the program (endurance and strength exercises in the same session, 60 min of duration, three times a week) and blood samples were collected before, 30 days and 180 days after the intervention started. Exercise training reduced the body mass index and body mass after 180 days of the intervention. A significant decrease on HDAC2 activity was found 180 days after intervention compared to before the intervention. The cortisol levels remained unchanged in any evaluated time-points. The concurrent exercise training was able to modulate HDAC2 activity in mononuclear cells and improve anthropometric variables in a time-dependent manner in patients with SZ.

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.

Histone deacetylase 10, a potential epigenetic target for therapy

Histone deacetylase (HDAC) 10, a class II family, has been implicated in various tumors and non-tumor diseases, which makes the discovery of biological functions and novel inhibitors a fundamental endeavor. In cancers, HDAC10 plays crucial roles in regulating various cellular processes through its epigenetic functions or targeting some decisive molecular or signaling pathways. It also has potential clinical utility for targeting tumors and non-tumor diseases, such as renal cell carcinoma, prostate cancer, immunoglobulin A nephropathy (IgAN), intracerebral hemorrhage, human immunodeficiency virus (HIV) infection and schizophrenia. To date, relatively few studies have investigated HDAC10-specific inhibitors. Therefore, it is important to study the biological functions of HDAC10 for the future development of specific HDAC10 inhibitors. In this review, we analyzed the biological functions, mechanisms and inhibitors of HDAC10, which makes HDAC10 an appealing therapeutic target.

Polygenic risk score, genome-wide association, and gene set analyses of cognitive domain deficits in schizophrenia

This study assessed genetic contributions to six cognitive domains, identified by the MATRICS Cognitive Consensus Battery as relevant for schizophrenia, cognition-enhancing, clinical trials. Psychiatric Genomics Consortium Schizophrenia polygenic risk scores showed significant negative correlations with each cognitive domain. Genome-wide association analyses identified loci associated with attention/vigilance (rs830786 within HNF4G), verbal memory (rs67017972 near NDUFS4), and reasoning/problem solving (rs76872642 within HDAC9). Gene set analysis identified unique and shared genes across cognitive domains. These findings suggest involvement of common and unique mechanisms across cognitive domains and may contribute to the discovery of new therapeutic targets to treat cognitive deficits in schizophrenia.

Interaction between polymorphisms in cell-cycle genes and environmental factors in regulating cholinesterase activity in people with exposure to omethoate

Cholinesterase activity (ChA), the effective biomarker for organophosphate pesticide exposure, is possibly affected by single nucleotide polymorphisms (SNPs) in cell-cycle-related genes. One hundred and eighty workers with long-term exposure to omethoate and 115 healthy controls were recruited to explore the gene-gene and gene-environment interactions. The acetylthiocholine and dithio-bis-(nitrobenzoic acid) method was used to detect the cholinesterase activities in whole blood, erythrocytes and plasma. Genetic polymorphisms were determined by the PCR-RFLP and direct PCR electrophoresis methods. Statistical results showed that the cholinesterase activities of whole blood, erythrocytes and plasma in the exposure group were significantly lower than those in the control group (p < 0.001), and erythrocyte cholinesterase activities were associated with gender, smoking and drinking in the exposure group (p < 0.05). Single-locus analyses showed that there is a statistically significant difference in the ChA among the genotypes CC, CA and AA of the p21 rs1801270 locus in the control group (p = 0.033), but not in the exposure group. A significant interaction between genes and environmental factors (i.e. p53, p21, mdm2, gender, smoking and drinking) affecting ChA was found through a generalized multifactor dimensionality reduction analysis. These obtained markers will be useful in further marker-assisted selection in workers with exposure to omethoate.

Disruption to schizophrenia-associated gene Fez1 in the hippocampus of HDAC11 knockout mice

Histone Deacetylase 11 (HDAC11) is highly expressed in the central nervous system where it has been reported to have roles in neural differentiation. In contrast with previous studies showing nuclear and cytoplasmic localisation, we observed synaptic enrichment of HDAC11. Knockout mouse models for HDACs 1-9 have been important for guiding the development of isoform specific HDAC inhibitors as effective therapeutics. Given the close relationship between HDAC11 and neural cells in vitro, we examined neural tissue in a previously uncharacterised Hdac11 knockout mouse (Hdac11 ^KO/KO). Loss of HDAC11 had no obvious impact on brain morphology and neural stem/precursor cells isolated from Hdac11 ^KO/KO mice had comparable proliferation and differentiation characteristics. However, in differentiating neural cells we observed decreased expression of schizophrenia-associated gene Fez1 (fasciculation and elongation protein zeta 1), a gene previously reported to be regulated by HDAC11 activity. FEZ1 has been associated with the dendritic growth of neurons and risk of schizophrenia via its interaction with DISC1 (disrupted in schizophrenia 1). Examination of cortical, cerebellar and hippocampal tissue reveal decreased Fez1 expression specifically in the hippocampus of adult mice. The results of this study demonstrate that loss of HDAC11 has age dependent and brain-region specific consequences.

[Genetics and epigenetics of schizophrenia and other psychoses]

Schizophrenia and other psychoses are categorical psychiatric diagnoses corresponding to frequent and heterogeneous disorders. Their physiopathology still remains largely unknown despite numerous recent advances. In particular, the last decade has identified different types of genetic variants, thanks to emergence of high-throughput methods. These methods allow both the identification of rare variants with a large effect such as punctual mutations or copy-number variants and the identification of frequent variants with a limited effect such as polymorphisms. Many impacted genes have been identified showing a very high genetic heterogeneity of psychoses. These genes are overrepresented in synaptic and neurotransmission pathways. Only a small fraction of psychoses could be easily explained by genetics but this screening in clinical practice is important as it can lead to therapeutic challenge or genetic counselling. Nowadays, it is clear that the pathophysiology of the psychoses can only be understood by an integrative approach taking into account the interaction between genes and environment. This interaction could be mediated by the epigenome defined as the modification of gene expression without changes in DNA sequence. Epigenome is stable but could be modified by environmental factors. Several epigenetic mechanisms have been studied in psychosis, in particular the DNA methylation, the modification of histones and the microRNA. All of these mechanisms are under regulation by genetic factors and variants in these epigenetic-involved genes and cofactors have been also associated with schizophrenia. Thus, pathophysiology of psychosis is complex and morestudiesare needed before definitive conclusions. Altogether, the recent advances in the genetics and epigenetics of psychosis are promising and could open the way to a recategorization of these disorders as well as the identification of new therapeutic targets.

The association between HDAC9 gene polymorphisms and stroke risk in the Chinese population: A meta-analysis

Several recent genome-wide association studies (GWASs) have suggested that the histone deacetylase 9 (HDAC9) gene is associated with stroke, but the reliability of these findings remains controversial, particularly for the data derived from different ethnicities and geographical locations. Therefore, we performed a meta-analysis to explore the associations between HDAC9 polymorphisms and the risk of stroke in the Chinese population. All eligible case-control studies that met the search criteria were retrieved from multiple databases, and six case-control studies with a total of 2,356 stroke patients and 3,420 healthy controls were included. The pooled odds ratios (ORs) with 95% confidence intervals (95% CIs) were calculated to assess the strengths of the associations of 3 HDAC9 gene polymorphisms with stroke risk. Our results revealed statistically significant associations of the rs2107595 (T/C) polymorphism with an increased risk of stroke in the allele, codominant and dominant models. Additionally, the rs2389995 (G/A) polymorphism was found to be significantly associated with a decreased risk of stroke in all genetic models. In conclusion, this meta-analysis suggested that the T allele of rs2107595 in HDAC9 increases the risk of stroke but that the G allele of rs2389995 decreases the risk of stroke in the Chinese population.

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.

Exercise-induced modulation of histone H4 acetylation status and cytokines levels in patients with schizophrenia

The present study aimed to investigate the short and long-term effects of a concurrent exercise protocol on global histone H4 acetylation levels and inflammatory markers (interleukin-4 (IL-4), interleukin-6 (IL-6), interferon gamma (IFN-γ) and cortisol) in phytohemagglutinin-stimulated peripheral blood mononuclear cells (PBMC) and in peripheral blood of patients with schizophrenia (SZ), as well the intervention impact on anthropometric characteristics. Seventeen individuals were submitted to the intervention three times a week and blood samples were collected pre, 30, 60 and 90days after the intervention started. A remarkable reduction on body mass index and body mass were observed following intervention. The protocol also induced a histone H4 hypoacetylation status in PBMC all times evaluated when compared to the pre intervention period. Although the IL-4 and cortisol levels were not altered in response to the intervention, a reduction in IL-6 production during the 60 and 90days compared to the pre intervention period was observed. Finally, diminished IFN-γ production was found in the 90days period compared to the pre intervention and 30days after periods. In addition, systemic IL-6 levels were lower at 60 and 90days compared to the pre intervention. The concurrent exercise protocol was able to improve anthropometric characteristics in patients with SZ, engaging the modulation of cytokine and histone H4 acetylation levels.