マウスモデルを用いたDOHaD検証系の確立：仔の行動表現型、遺伝子発現、ゲノムメチル化に関する網羅的解析

第3回日本DOHaD研究会学術集会　抄録集　【ポスター発表

Epigenetic Mechanisms and Therapeutic Perspectives for Neurodevelopmental Disorders

The number of children with mild neurodevelopmental disorders, such as autism, has been recently increasing in advanced countries. This increase is probably caused by environmental factors rather than genetic factors, because it is unlikely that genetic mutation rates suddenly increased within a short period. Epigenetics is a mechanism that regulates gene expression, depending not on the underlying DNA sequence but on the chemical modifications of DNA and histone proteins. Because mental stress can alter the epigenetic status in neuronal cells, environmental factors may alter brain function through epigenetic changes. However, one advantage of epigenetic changes is their reversibility. Therefore, diseases due to abnormal epigenetic regulation are theoretically treatable. In fact, several drugs for treating mental diseases are known to have restoring effects on aberrant epigenetic statuses, and a novel therapeutic strategy targeting gene has been developed. In this review, we discuss epigenetic mechanisms of congenital and acquired neurodevelopmental disorders, drugs with epigenetic effects, novel therapeutic strategies for epigenetic diseases, and future perspectives in epigenetic medicine

Protein-restricted diet during pregnancy after insemination alters behavioral phenotypes of the progeny

Abstract Background Epidemiological studies suggest that hyponutrition during the fetal period increases the risk of mental disorders such as attention deficit hyperactivity disorder and autism-spectrum disorder, which has been experimentally supported using animal models. However, previous experimental hyponutrition or protein-restricted (PR) diets affected stages other than the fetal stage, such as formation of the egg before insemination, milk composition during lactation, and maternal nursing behavior. Results We conducted in vitro fertilization and embryo transfer in mice and allowed PR diet and folic acid-supplemented PR diet to affect only fetal environments. Comprehensive phenotyping of PR and control-diet progenies showed moderate differences in fear/anxiety-like, novelty-seeking, and prosocial behaviors, irrespective of folic-acid supplementation. Changes were also detected in gene expression and genomic methylation in the brain. Conclusions These results suggest that epigenetic factors in the embryo/fetus influence behavioral and epigenetic phenotypes of progenies. Significant epigenetic alterations in the brains of the progenies induced by the maternal-protein restriction were observed in the present study. To our knowledge, this is first study to evaluate the effect of maternal hyponutrition on behavioral phenotypes using reproductive technology

The protocadherins, <it>PCDHB1 </it>and <it>PCDH7</it>, are regulated by MeCP2 in neuronal cells and brain tissues: implication for pathogenesis of Rett syndrome

<p>Abstract</p> <p>Background</p> <p>Rett syndrome is a neurodevelopmental and autistic disease caused by mutations of <it>Methyl-CpG-binding protein 2 </it>(<it>MECP2</it>) gene. MeCP2 protein is mainly expressed in neurons and binds to methylated gene promoters to suppress their expression, indicating that Rett syndrome is caused by the deregulation of target genes in neurons. However, it is likely that there are more unidentified neuronal MeCP2-targets associated with the neurological features of RTT.</p> <p>Results</p> <p>Using a genome-microarray approach, we found 22 genomic regions that contain sites potentially regulated by MeCP2 based on the features of MeCP2 binding, DNA methylation, and repressive histone modification in human cell lines. Within these regions, Chromatin immunoprecipitation (ChIP) analysis revealed that MeCP2 binds to the upstream regions of the protocadherin genes <it>PCDHB1 </it>and <it>PCDH7 </it>in human neuroblastoma SH-SY5Y cells. PCDHB1 and PCDH7 promoter activities were down-regulated by MeCP2, but not by MBD-deleted MeCP2. These gene expression were up-regulated following MeCP2 reduction with siRNA in SH-SY5Y cells and in the brains of <it>Mecp2</it>-null mice. Furthermore, <it>PCDHB1 </it>was up-regulated in postmortem brains from Rett syndrome patients.</p> <p>Conclusions</p> <p>We identified MeCP2 target genes that encode neuronal adhesion molecules using ChIP-on-BAC array approach. Since these protocadherin genes are generally essential for brain development, aberrant regulation of these molecules may contribute to the pathogenesis of the neurological features observed in Rett syndrome.</p

Adverse effects of an active fragment of parathyroid hormone on rat hippocampal organotypic cultures

1. Adverse effects of an active fragment of parathyroid hormone (PTH(1–34)), a blood Ca(2+) level-regulating hormone, were examined using rat hippocampal slices in organotypic culture. 2. Exposure of cultured slice preparations to 0.1 μM PTH(1–34) for 60 min resulted in a gradual increase in the intracellular Ca(2+) concentration ([Ca(2+)](i)); this effect was most obvious in the apical dendritic region of CA1 subfield. 3. When PTH(1–34) at a lower concentration (1 nM) was added to the culture medium and its toxic effects examined using a propidium iodide intercalation method, significant toxicity was seen 3 days after exposure and increased with time. Cells in the CA1 region seemed more vulnerable to the hormone than cells in other regions. At 1 week of exposure, the toxic effects were dose-dependent over the range of 0.1 pM to 0.1 μM, the minimum effective dose being 10 pM. 4. The adverse effects were not induced either by the inactive fragment, PTH(39–84), or by an active fragment of PTH-related peptide (PTHrP(1–34)), an intrinsic ligand of the brain PTH receptor. 5. The PTH(1–34)-induced adverse effects were significantly inhibited by co-administration of 10 μM nifedipine, an L-type Ca(2+) channel blocker, but not by co-administration of blockers of the other types of Ca(2+) channel. 6. The present study demonstrates that sustained high levels of PTH in the brain might cause degeneration of specific brain regions due to Ca(2+) overloading via activation of dihydropyridine-sensitive Ca(2+) channels, and suggests that PTH may be a risk factor for senile dementia