Antipsychotic-induced epigenomic reorganization in frontal cortex samples from individuals with schizophrenia

Genome wide association studies have revealed >150 loci associated with schizophrenia risk1-4, yet these genetic factors do not seem to be sufficient to fully explain the molecular determinants behind this psychiatric condition. Epigenetic marks such as post-translational histone modifications remain largely plastic during development and adulthood, allowing a dynamic impact of environmental factors, including antipsychotic medications, on access to genes and regulatory elements5,6. However, no study so far has profiled cell-specific genome-wide histone modifications in postmortem brain samples from schizophrenia subjects or the effect of antipsychotic treatment on such epigenetic marks. Here we show the first comprehensive epigenomic characterization of the frontal cortex of 29 individuals with schizophrenia and 29 matched controls, including histone modifications associated with active promoters and enhancers H3K4me3 and H3K27ac along with RNA expression in neuronal and glial nuclei. Schizophrenia subjects exhibited thousands of cell type-specific epigenetic differences at regions that included several susceptibility genetic loci, such as NRG1, RGS4 and HTR2A. Comparing untreated and treated schizophrenia subjects with controls, our findings provide entirely new insights into differentially modified genes associated with unexpected pathways that are potential markers of antipsychotic treatment. Additionally, we show that the effect of age on the epigenomic landscape is more pronounced in frontal cortex samples of antipsychotic-treated schizophrenia subjects. Together, our data provide important evidence of epigenetic alterations in the frontal cortex of individuals with schizophrenia, and remark the impact of age and antipsychotic treatment on chromatin organization.