Epidemiological evidence suggests that etiology of schizophrenia may involve both the influence of genetic factors specific for the individual and the impact of the environment. It is quite likely that a crucial role in the disease development is played by molecular mechanisms mediating the interaction between genes and environment. Modern research have shown that epigenetic mechanisms or chemical modifications of deoxyribonucleic acids (DNA) and histone proteins remain unstable throughout life and can be changed by environmental factors.
This article constructs an argument for using blood chromatin (contained in nucleated blood cells) as a protein biosensor to integrate the ambient epigenetic influences in the internal milieu. An analogy is made to blood glycated hemoglobin (HbA1c) in diabetes as an integrated proxy for glucose levels and body-wide protein glycation. Genome-wide chromatin can serve as an organizing principle that bridges the central and peripheral compartments by entraining commensurable gene networks.
Chronic drug exposure alters gene expression in the brain and produces long-term changes in neural networks that underlie compulsive drug taking and seeking. Exactly how drug-induced changes in synaptic plasticity and subsequent gene expression are translated into persistent neuroadaptations remains unclear. Emerging evidence suggests that complex drug-induced neuroadaptations in the brain are mediated by highly synchronized and dynamic patterns of gene regulation.
Nihon Shinkei Seishin Yakurigaku Zasshi = Japanese Journal of Psychopharmacology
Recent research has demonstrated that complex 'epigenetic' mechanisms, which regulate gene transcription without altering the DNA code, could play a critical role in the pathophysiology of psychiatric disorders. We previously reported that pretreatment of mice with 5-HT(1A) receptor agonists 24 hr before testing suppressed the decrease in emotional behaviors induced by exposure to acute restraint stress.
European Archives of Psychiatry and Clinical Neuroscience
Notwithstanding the considerable advances in the treatment options for schizophrenia, the cognitive symptoms in particular are not receptive to antipsychotic treatment and considered one of the main predictors for poor social and functional outcome of the disease. Recent findings in preclinical model systems indicate that epigenetic modulation might emerge as a promising target for the treatment of cognitive disorders.
Epigenetic mechanisms, i.e. the control gene of expression without changing DNA sequence, include DNA methylation, histone post-translational modifications (PTMs) and microRNAs (miRNAs). Aberrant epigenetic modifications are associated with several pathological conditions, including brain diseases, resulting from environmental causes, ageing or genetic factors. The role of histone PTMs, including acetylation, phosphorylation, methylation and ubiquitylation, has been demonstrated in learning and memory, both in physiological conditions and in neuropathologies.
Mis-regulation of gene expression due to epigenetic abnormalities has been linked with complex genetic disorders, psychiatric illness, and cancer. In addition, the dynamic epigenetic changes that occur in pluripotent stem cells are believed to impact regulatory networks essential for proper lineage development. Chromatin immunoprecipitation (ChIP) is a technique used to enrich genomic fragments using antibodies against specific chromatin modifications, such as DNA-binding proteins or modified histones.
OBJECTIVE: Epigenetic changes are stable and long-lasting chromatin modifications that regulate genomewide and local gene activity. The addition of two methyl groups to the 9th lysine of histone 3 (H3K9me2) by histone methyltransferases (HMT) leads to a restrictive chromatin state, and thus reduced levels of gene transcription. Given the numerous reports of transcriptional down-regulation of candidate genes in schizophrenia, we tested the hypothesis that this illness can be characterized by a restrictive epigenome.
A large, and still rapidly expanding literature on epigenetic regulation in the nervous system has provided fundamental insights into the dynamic regulation of DNA methylation and post-translational histone modifications in the context of neuronal plasticity in health and disease. Remarkably, however, very little is known about the potential role of chromatin-bound RNAs, including many long non-coding transcripts and various types of small RNAs.
Proceedings of the National Academy of Sciences of the United States of America
Transcriptional dysregulation is an early feature of Huntington disease (HD). We observed gene-specific changes in histone H3 lysine 4 trimethylation (H3K4me3) at transcriptionally repressed promoters in R6/2 mouse and human HD brain. Genome-wide analysis showed a chromatin signature for this mark. Reducing the levels of the H3K4 demethylase SMCX/Jarid1c in primary neurons reversed down-regulation of key neuronal genes caused by mutant Huntingtin expression. Finally, reduction of SMCX/Jarid1c in primary neurons from BACHD mice or the single Jarid1 in a Drosophila HD model was protective.