Probing the Protective Role of EZH2 in Epilepsy

项目摘要/摘要 癫痫是继中风、阿尔茨海默氏症和偏头痛之后第四大最常见的神经系统疾病 发病率为每26人中有1人。虽然有许多抗惊厥药物可供选择，但没有 减缓疾病进展的抗癫痫药物。使用新的生物信息学方法， 我们已经确定了大脑在长期癫痫发作后启动的内源性保护程序 减轻病变的功能。 癫痫的发生与大脑中过多的变化有关，包括可塑性的改变， 细胞死亡、神经再生、炎症和轴突萌发。这些变化在不同的时间范围内发生 从几分钟到几年，但编排机制几乎是未知的。中国的长期变化 与癫痫发生相关的基因表达意味着一个或多个主控调控因子 转录可能正在协调大脑的变化。为了揭示这些转录机制， 我们求助于我们最近发表的由癫痫微阵列生成的全基因组表达数据集 财团(EMC)。这些数据集包括大鼠齿状回颗粒细胞的mRNA表达谱 癫痫持续状态(SE)后的不同时间点。使用一种新的生物信息学工具，将整个 基因组转录因子结合数据与基因表达谱，我们分析了来自 在两个独立的实验室，在不同的时间点，用三种不同的惊厥刺激诱导大脑。这 分析预测，Polycomb靶基因代表了大多数长期改变的基因 癫痫的发生。REST靶标代表第二组重叠的、被抑制的基因。Polycomb是一种 众所周知，基因表达终生变化的驱动因素是通过表观遗传学沉默基因 这个门类。我们的数据显示，EZH2蛋白(EZH2蛋白的催化甲基酶亚单位)的诱导非常强劲 Polycomb)在20天的窗柱上的神经元SE。此外，我们发现，在不久之后对抗EZH2 Se强烈加速小鼠自发性反复发作，提示了一种保护性的而不是 而不是EZH2的病理作用。EZH2在SE后的拮抗作用如何仍有待确定。 在这个项目中，我们将测试这样的假设，即Polycomb输出中的变化是 癫痫的发生。我们将确定EZH2上调是否总是保护性的，或者它的作用是否演变 在潜伏期内。我们将测试EZH2水平的数量级变化对辅阻遏子的影响 功能来观察这种上调是增强还是阻碍了两个主要的EZH2的抑制能力 含有复合体：多梳和REST。我们预计这些研究将确定Polycomb为 与癫痫发生相关的长期变化的主要策划者。如果是这样的话，接近 调制多梳函数可能会使全球6500万人受益 癫痫。

Project Summary/Abstract Epilepsy is the 4th most prevalent neurological disorder after stroke, Alzheimer’s and migraine with an incidence of 1 in 26 individuals. Though there are a number of anti-convulsant drugs available, there are no anti-epileptogenic drugs that mitigate the progression of the disease. Using novel bioinformatic approaches, we have identified an endogenous, protective program launched by the brain after a prolonged seizure that functions to mitigate pathological changes. Epileptogenesis is associated with a plethora of changes in the brain including alterations in plasticity, cell death, neurogenesis, inflammation and axonal sprouting. These changes occur over timescales ranging from many minutes to years, but the orchestrating mechanisms are virtually unknown. Long-term changes in gene expression that are associated with epileptogenesis imply that one or more master regulators of transcription may be coordinating the brain alterations. In order to uncover these transcriptional mechanisms, we turned to our recently published genome-wide expression datasets generated by the Epilepsy Microarray Consortium (EMC). The datasets consist of mRNA expression profiles of rat dentate granule cells assayed at various time points after Status Epilepticus (SE). Using a novel bioinformatic tool that integrates whole genome transcription factor binding data with gene expression profiles, we analyzed datasets derived from brains induced by 3 different convulsant stimuli, each in 2 independent labs, and at various time-points. This analysis projected that Polycomb target genes represent the majority of chronically altered genes during epileptogenesis. REST targets represent a second, overlapping, group of repressed genes. Polycomb is a well-known driver of life-long changes in gene expression that works by epigenetically silencing genes across the phyla. Our data shows an extremely robust induction of EZH2 protein (the catalytic methylase subunit of Polycomb) over a 20 day window post SE in neurons. Further, we find that antagonizing EZH2 shortly after SE robustly accelerates the onset of spontaneous recurrent seizures in mice, suggesting a protective rather than pathological role for EZH2. How antagonism of EZH2 later after SE remains to be determined. In this project, we will test the hypothesis that an alteration in Polycomb output is a principal modifier of epileptogenesis. We will ascertain whether EZH2 upregulation is always protective or whether its role evolves during the latent period. We will test the effect of an order-of-magnitude change in EZH2 levels on corepressor function to see whether such upregulation augments or hampers the repressive abilities of two major EZH2 containing complexes: Polycomb and REST. We anticipate that these studies will establish Polycomb as a major orchestrator of the long-term changes associated with epileptogenesis. If so, approaches that modulate Polycomb function may be of benefit to the 65 million people world-wide that live with epilepsy.