Nagai Kaoru, Natori Takamitsu, Nishino Toru, Kodaira Fumiaki
Department of Epigenetic Medicine, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi 409-3898, Japan.
J Biosci Bioeng. 2008 May;105(5):470-5. doi: 10.1263/jbb.105.470.
Some epigenetic mechanisms, including DNA methylation and histone deacetylation, act as transcriptional repression signals. In this study, we examined whether DNA methylation dependent transcriptional control regulates glial cell growth. Primary cultured mouse cortical glial cells were treated with the DNA methylation inhibitor 5-aza-deoxycytidine (5adC) or the histone deacetylase inhibitor sodium valproate (VPA), which inhibits DNA-methylation-dependent transcriptional repression. 5adC significantly reduced methylated C level determined by reversed-phase high-performance liquid chromatography (HPLC), while VPA did not. Treatments with these inhibitors significantly reduced cell number determined by MTT assay after 48 h. Both 5adC and VPA showed little cellular toxicity observed by live and dead cell staining. In contrast, both 5adC and VPA induced an abnormality in the cell cycle. Cells treated with the inhibitors represented a significantly higher ratio in the G2+M-phase and 5adC-treated cells showed a significantly lower ratio in the S-phase. Regarding the in vivo effect, prenatal treatment with VPA, which is an autistic model in rodents, significantly reduced the brain/body weight ratio in early postnatal days. Our data indicate that DNA-methylation- and histone-deacetylation-dependent transcriptional control is crucial for the regulation of glial cell growth. Our data suggest that abnormalities of epigenetic transcriptional regulatory mechanisms in glial cells cause an abnormal brain size, which may in turn cause mental diseases.
一些表观遗传机制，包括DNA甲基化和组蛋白去乙酰化，充当转录抑制信号。在本研究中，我们检测了DNA甲基化依赖性转录调控是否调节神经胶质细胞的生长。用DNA甲基化抑制剂5-氮杂脱氧胞苷（5adC）或组蛋白去乙酰化酶抑制剂丙戊酸钠（VPA）处理原代培养的小鼠皮质神经胶质细胞，后者抑制DNA甲基化依赖性转录抑制。5adC通过反相高效液相色谱（HPLC）测定显著降低了甲基化C水平，而VPA则没有。用这些抑制剂处理48小时后，通过MTT法测定细胞数量显著减少。通过活细胞和死细胞染色观察，5adC和VPA均显示出几乎没有细胞毒性。相反，5adC和VPA均诱导细胞周期异常。用抑制剂处理的细胞在G2+M期的比例显著更高，而用5adC处理的细胞在S期的比例显著更低。关于体内效应，用VPA进行产前治疗（这是啮齿动物的自闭症模型）在出生后早期显著降低了脑/体重比。我们的数据表明，DNA甲基化和组蛋白去乙酰化依赖性转录调控对于神经胶质细胞生长的调节至关重要。我们的数据表明，神经胶质细胞中表观遗传转录调控机制的异常会导致脑尺寸异常，进而可能导致精神疾病。
