Genome-wide expression analysis of ischemic neuronal injury based on functional genomics and proteomics

短暂性脑缺血导致脆弱的海马区CA1区选择性和延迟性神经元死亡。各种研究表明，脑缺血可诱导多种基因的转录激活，特别是与应激反应、细胞死亡或存活相关的基因，提示脑缺血与神经元的易损性密切相关。DNA微阵列技术的最新进展为在一次杂交实验中分析数千个基因的表达提供了工具。应用这些技术，利用基于寡核苷酸的DNA芯片，对大鼠全脑缺血模型的CA1区全基因组基因表达进行了分析，结果表明，脑缺血后246个转录本的表达水平上升，213个转录本的表达水平下降，相当于所代表的探针组的5.1%。使用层次聚类分析将这些变化划分为七个表达簇，每个表达簇具有不同的条件和特定的时间模式。缺血耐受与转录因子(c-Fos、JunB Egr-1、-2、-4、NGFI-B)、Hsp70和MAP-K级联相关基因(MKP-1)的瞬时上调有关，这些基因与细胞存活有关。迟发性神经元死亡表现出复杂而持久的表达变化，如促凋亡基因(Gadd153、Smad2、dral、Caspase-2和-3)的上调以及与存活信号相关的基因(MKK2、P4激酶、DAG/PKC信号通路)的下调，提示死亡和存活信号之间的失衡。本研究提供了迟发性神经元死亡和诱导缺血耐受之间的全基因组差异基因表达谱，有助于进一步了解脑缺血复杂的分子病理生理机制。

Transient cerebral ischemia causes selective and delayed neuronal death in the vulnerable hippocampal CA1 region. Various studies have provided evidence that cerebral ischemia induces transcriptional activation of a variety of genes, particularly those related to stress response, cell death or survival, suggesting a close relationship with neuronal ischemic vulnerability. Recent advances in DNA microarray technology have provided tools to analyze the expression of thousands of genes in a single hybridization experiment. Employing these techonogies, genome-wide gene expression analysis of the hippocampal CA1 region was conducted in a rat global ischemia model for delayed neuronal death and induced ischemic tolerance using an oligonucleotide-based DNA microarray containing 8,799 probes.The results showed that expression levels of 246 transcripts were increased and 213 were decreased following ischemia, corresponding to 5.1% of the represented probe sets. These changes were divided into seven expression clusters using hierarchical cluster analysis, each with distinct conditions and time-specific patterns. Ischemic tolerance was associated with transient up-regulation of transcription factors (c-Fos, JunB Egr-1,-2,-4, NGFI-B), Hsp70 and MAP kinase cascaderelated genes (MKP-1), which are implicated cell survival. Delayed neuronal death exhibited complex long-lasting changes of expression, such as up-regulation of proapoptotic genes (GADD 153, Smad2, Dral, Caspase-2 and -3) and downregulation of genes implicated in survival signaling (MKK2, and PI4 kinase, DAG/PKC signaling pathways), suggesting an imbalance between death and survival signals.Our study provides a differential gene expression profile between delayed neuronal death and induced ischemic tolerance in a genomewide analysis, and contributes to further understanding of the complex molecular pathophysiology in cerebral ischemia.