Hiremath Girish K, Tilelli Cristiane Q, Xu Yaomin, Gopalan Banu, Najm Imad M
Department of Neurosurgery, Cleveland Clinic, Cleveland, Ohio 44195, USA.
Epileptic Disord. 2009 Sep;11(3):232-43. doi: 10.1684/epd.2009.0270. Epub 2009 Sep 1.
Cortical Dysplasia (CD) is the histopathological substrate in almost half of all drug-resistant focal epilepsies. Little is known about the gene expression profile of CD. As such information may help target therapeutics more effectively, our aim was to perform a gene expression analysis of an animal model of cortical dysplasia induced by in utero irradiation.
Nine offspring from irradiated animals, and nine age-matched controls were sacrificed at post-natal day 60. Cortical and hippocampal regions were separated, and total ribonucleic acid (RNA) was extracted using a commercially available kit (Qiagen). RNA was then subjected to a gene expression analysis using an oligonucleotide microarray platform (Illumina). After statistical analysis, genes were considered differentially expressed when a p value less than 0.001 was observed. Real-time, quantitative polymerase chain reaction (RT-qPCR) was used to confirm microarray results for three genes via the Livak method.
Twenty three genes from cortical tissue met criteria for altered gene expression. Six genes from cortex seemed relevant to the pathogenesis of CD. Two genes that promoted cell survival (connective tissue growth factor and peroxiredoxin) were upregulated. One gene that promoted excitotoxic neurodegeneration (latrophilin-2) was downregulated. Two genes involved in glutamate (protein kinase C-alpha) and AMPA receptor recycling (NEEP-21) were downregulated. One gene, (Shank-1) involved in the control of dendritic maturation, was downregulated.
Gene expression analysis in this animal model revealed some of the potential mechanisms by which CD may lead to the phenotype of intractable epilepsy. The downregulation of genes that are involved in glutamate and AMPA receptor recycling may lead to increased excitability. Disinhibition of aberrant dendritic branching, resulting from a downregulation of Shank-1, may also result in an increase in sprouting, excitation and/or hypersynchrony. Finally, genes promoting cell survival, either directly (connective tissue growth factor, peroxiredoxin) or indirectly (latrophilin-2) may allow CD tissue to survive the excitotoxic injury that it produces, thus allowing it to perpetuate the epileptic condition over time.
皮质发育异常（CD）是几乎一半耐药性局灶性癫痫的组织病理学基础。关于CD的基因表达谱知之甚少。由于此类信息可能有助于更有效地靶向治疗，我们的目的是对子宫内照射诱导的皮质发育异常动物模型进行基因表达分析。
在出生后第60天处死9只受照射动物的后代和9只年龄匹配的对照动物。分离皮质和海马区域，使用市售试剂盒（Qiagen）提取总核糖核酸（RNA）。然后使用寡核苷酸微阵列平台（Illumina）对RNA进行基因表达分析。经过统计分析，当观察到p值小于0.001时，基因被认为是差异表达的。使用实时定量聚合酶链反应（RT-qPCR）通过Livak方法确认三个基因的微阵列结果。
来自皮质组织的23个基因符合基因表达改变的标准。来自皮质的6个基因似乎与CD的发病机制相关。两个促进细胞存活的基因（结缔组织生长因子和过氧化物酶）上调。一个促进兴奋性毒性神经变性的基因（latrophilin-2）下调。两个参与谷氨酸（蛋白激酶C-α）和AMPA受体再循环（NEEP-21）的基因下调。一个参与树突成熟控制的基因（Shank-1）下调。
该动物模型中的基因表达分析揭示了CD可能导致难治性癫痫表型的一些潜在机制。参与谷氨酸和AMPA受体再循环的基因下调可能导致兴奋性增加。Shank-1下调导致异常树突分支的去抑制，也可能导致发芽、兴奋和/或超同步增加。最后，直接（结缔组织生长因子、过氧化物酶）或间接（latrophilin-2）促进细胞存活的基因可能使CD组织在其产生的兴奋性毒性损伤中存活，从而使其随着时间的推移使癫痫状况持续存在。
