GAD1 mRNA Expression and DNA Methylation in Prefrontal Cortex of Subjects with Schizophrenia
GAD1 mRNA Expression and DNA Methylation in Prefrontal Cortex of Subjects with Schizophrenia
复制标题
DOI：
10.1371/journal.pone.0000809
复制
发表时间：
2007-08-29
期刊：
影响因子：
3.7
通讯作者：
Akbarian, Schahram
中科院分区：
文献类型：
--
作者：
Huang, Hsien-Sung;Akbarian, Schahram
精神分裂症患者的前额皮质功能障碍包括GABA能mRNA的变化，包括GAD 1表达减少，GAD 1编码67 kDa谷氨酸脱羧酶（GAD（67））GABA合成酶。潜在的分子机制仍不清楚。DNA甲基化作为基因表达的表观遗传调节因子的改变被认为起作用，但这一假设很难检验，因为没有技术可用于从人死后脑中有效地从表达GAD 1的神经元中提取DNA。在这里，我们提出了一种替代的方法，是基于免疫沉淀的单核细胞与抗甲基组蛋白抗体区分潜在的基因表达的位点，而不是抑制或沉默的染色质。在GAD 1近端启动子和内含子2的CpG二核苷酸的甲基化模式分别为两个染色质组分的每一个确定，使用病例对照设计的14名精神分裂症受试者的前额GAD 1 mRNA水平下降的影响。在对照组中，CpG二核苷酸的甲基化频率虽然总体上在抑制性染色质中高于开放染色质，但在近端GAD 1启动子处不超过5%，在内含子2内不超过30%。精神分裂症受试者在抑制性染色质相关的DNA甲基化启动子处表现出显著的平均8倍缺陷。这些结果表明，染色质重塑机制参与了GABA能基因表达失调的精神分裂症。
Dysfunction of prefrontal cortex in schizophrenia includes changes in GABAergic mRNAs, including decreased expression of GAD1, encoding the 67 kDa glutamate decarboxylase (GAD(67)) GABA synthesis enzyme. The underlying molecular mechanisms remain unclear. Alterations in DNA methylation as an epigenetic regulator of gene expression are thought to play a role but this hypothesis is difficult to test because no techniques are available to extract DNA from GAD1 expressing neurons efficiently from human postmortem brain. Here, we present an alternative approach that is based on immunoprecipitation of mononucleosomes with anti-methyl-histone antibodies differentiating between sites of potential gene expression as opposed to repressive or silenced chromatin. Methylation patterns of CpG dinucleotides at the GAD1 proximal promoter and intron 2 were determined for each of the two chromatin fractions separately, using a case-control design for 14 schizophrenia subjects affected by a decrease in prefrontal GAD1 mRNA levels. In controls, the methylation frequencies at CpG dinucleotides, while overall higher in repressive as compared to open chromatin, did not exceed 5% at the proximal GAD1 promoter and 30% within intron 2. Subjects with schizophrenia showed a significant, on average 8-fold deficit in repressive chromatin-associated DNA methylation at the promoter. These results suggest that chromatin remodeling mechanisms are involved in dysregulated GABAergic gene expression in schizophrenia.