シンポジウム

シンポジウム Epigenetics in neurological and psychiatric diseases

3S3-1 Epigenetic alterations in neuronal cells of patients with bipolar disorder and schizophrenia Iwamoto Kazuya¹，Kato Tadafumi² ¹Department of Molecular Psychiatry, Graduate School of Medicine, the University of Tokyo，²Laboratory for Molecular Psychiatry, RIKEN BSI Despite the extensive efforts, genetic factors involved in major psychiatric disorders such as bipolar disorder（BD）and schizophrenia（SZ）can explain only a part of their pathophysiology. Accumulating evidence suggests that epigenetic factors such as cytosine and histone modifications are involved in not only fundamental and higher brain functions but also the pathophysiology of psychiatric disorders. We comprehensively analyzed DNA methylation profiles of neuronal and non-neuronal nuclei derived from frozen prefrontal cortex samples of patients and controls. Bioinformatic analysis of differentially methylated regions revealed the propensity of promoter-wide hypomethylation in addition to hypermethylation of neuronal function-related genes in BD and SZ. Using cell culture and animal models, we systematically assessed the effect of mood stabilizers and antipsychotics, and found that they may account for only minor fraction of DNA methylation changes detected in brain. Our results suggest that further epigenetic analyses in the brain will contribute to understand the pathophysiology of psychiatric disorders. Our ongoing analyses focusing on various cytosine modifications in more specific cell types, and comparative neuronal epigenomics for understanding the role of epigenetics on neuronal functions will be discussed.		3S3-2 A role for inefficient RNA editing in the amyotrophic lateral sclerosis（ALS）pathogenesis Kwak Shin¹ ¹Div. of Clin. Biotech., Centr. for Dis. Biol. and Integ. Med., Grad. School of Med., Univ. of Tokyo，²Internatl. Univ. of Health and Welfare Motor neurons of the majority of amyotrophic lateral sclerosis（ALS）cases express abnormal GluA2 that possesses glutamine（Q）instead of arginine（R）at the Q/R site due to failure of adenosine to inosine（A-to-I）conversion. This molecular abnormality results from down-regulation of the RNA editing enzyme adenosine deaminase acting on RNA 2（ADAR2）that specifically catalyzes A-to-I conversion at the Q/R site of GluA2 pre-mRNA. AMPA receptors containing unedited GluA2 are highly permeable to Ca²⁺, and resultant exaggerated Ca²⁺ influx causes slow death of motor neurons in conditional ADAR2 knockout（AR2）mice. Notably, ADAR2-lacking motor neurons in the AR2 mice exhibit TDP-43 pathology, the most reliable neuropathological hallmark of ALS. Furthermore, TDP-43 pathology and ADAR2 down-regulation are concomitantly observed in the same motor neurons of ALS patients. These lines of evidence indicate that ADAR2 down-regulation is involved in the ALS pathogenic mechanism and a molecular target for ALS therapy. Therefore, we developed a gene therapy for ALS by the delivery of the ADAR2 gene to the mouse motor neurons using an adeno-associated virus（AAV）vector. A single intravenous injection of AAV-ADAR2 successfully prevented AR2 mice from developing clinical and pathological ALS phenotype. In this symposium, I would like to present that failure of RNA processing causes human disease and normalization of the RNA processing is a possible therapeutic strategy.

3S3-3 Epigenetic studies in Alzheimer's disease Lunnon Katie，Smith Rebecca，Hannon Eilis，Jager Philip De，Srivastava Gyan，Volta Manuela，Troakes Claire，Al-Sarraj Safa，Burrage Joe，Macdonald Ruby，Condliffe Daniel，Katsel Pavel，Haroutunian Vahram，Kaminsky Zachary，Joachim Catharine，Harries Lorna，Powell John，Lovestone Simon，Bennett David A.，Schalkwyk Leonard，Mill Jonathan University of Exeter Background Increasing knowledge about the biology of the genome has implicated an important role for epigenetic variation in human health and disease, and recent methodological advances mean that epigenome-wide association studies (EWAS) are now feasible for complex disease phenotypes including Alzheimer’s disease. Epigenetic epidemiology is a relatively new endeavor, however, and there are important considerations regarding study design, tissue-type, analysis strategy and data interpretation. Here we describe two systematic cross-tissue EWAS analyses of DNA methylation in AD using a powerful sequential replication design, with the goal of identifying disease-associated methylomic variation across pathologically-relevant regions of the brain. Methods We used the Illumina Infinium Human Methylation 450K BeadChip to assess genome-wide methylation at >485,000 CpG sites in a discovery cohort of 117 individuals from the London MRC Brain Bank. We profiled multiple brain regions (prefrontal cortex, entorhinal cortex, superior temporal gyrus and cerebellum) representing the spectrum of AD pathology and matched samples collected pre-mortem. Differentially methylated positions (DMPs) of interest were validated in a second independent cohort of 144 individuals from the Mount Sinai Brain Bank. Data was analysed using various R packages to identify differentially methylated loci important in disease, including network analyses, pathway analyses and a sliding window approach to identify differentially methylated regions (DMRs) spanning multiple DMPs. Results Data was analysed using various R packages to identify differentially methylated loci important in disease, including network analyses, pathway analyses and a sliding window approach to identify differentially methylated regions (DMRs) spanning multiple DMPs.In our discovery cohort we identified a number of differentially methylated regions (DMRs) in cortical regions, which were associated with neuropathological measures of Alzheimer’s disease. Many of these were validated in our independent replication cohort. Conclusions This study provides compelling evidence for an association between epigenomic dysfunction and AD-related neuropathology. This study represents the first epigenome-wide association study (EWAS) of AD employing a sequential replication design across multiple tissues, highlighting the power of this strategy for the identification of disease-associated DMRs.		3S3-4 Behavioral consequences of dysmyelination Macklin Wendy B.，Gould Elizabeth，Restrepo Diego Department of Cell and Developmental Biology, University of Colorado School of Medicine. Myelin is required for proper nerve conduction and has an important role in normal neuronal function. Polymorphisms in myelin genes are associated with neurologic and psychiatric diseases. However, little is known about the neuronal and behavioral consequences of myelin disruption and the role of myelin genes in pathology. To address the contribution of myelin function to behavioral and cognitive deficits, we investigated behavior in the proteolipid protein (PLP)-null mouse. These mice generate myelin but they exhibit progressive myelin dysfunction and subsequent axonal degeneration. We tested 3 and 8 month-old PLP knockout PLP(-/Y) male mice in several behavioral tests. No motor deficits were observed in 3 and 8 month old PLP(-/Y) mice on the Rotarod, a classical test of motor function. In an open field test, 8 month PLP(-/Y) mice spent less time in the center of the open field, while exploration of the walls was increased. PLP(-/Y) mice had decreased motivation to bury marbles in the marble burying task, in which the number of marbles buried in 10 minutes is quantified. This is an instinctive behavior, but 3 month PLP(-/Y) mice buried fewer marbles and by 8 months they buried almost none. Their performance on the Y maze, a test of spatial memory and hippocampal function, was normal at both ages. However, their behavior in the Puzzle Box, a test of problem-solving and executive function, suggested deficits in problem solving. The Puzzle Box involves moving from a lighted box into a darkened goal box. The entry to the goal box becomes increasingly difficult, initially by covering it, then putting sawdust into it and finally covering the sawdust-filled entry. The 3 and 8 month PLP(-/Y) mice displayed cognitive deficits evidenced by longer latency to reach the goal box when presented with the new challenges. Intriguingly, 3 and 8 month PLP(-/Y) mice exhibit a significant increase in immobility and a lack of coordinated swimming behavior when placed in water. We are currently investigating why there is a swimming deficit in PLP(-/Y) mice. These behavioral results indicate that myelin dysfunction prior to significant axonal degeneration results in targeted behavioral deficits and cognitive dysfunction. Ongoing investigation aims at refining the characterization of these deficits and linking them to structural alteration of myelin in specific areas of the brain. Supported by NS25304.