Kamphuis Willem, Dijk Frederike, Bergen Arthur A B
Department of Molecular Ophthalmogenetics, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, The Netherlands.
Mol Vis. 2007 Oct 5;13:1892-901.
Ischemic conditions in the retina have been implicated in several retinopathological conditions. Experimentally induced ischemia for 60 min followed by reperfusion leads to a loss of neurons in the inner retina. In contrast, a 5 min ischemic episode triggers a series of alterations that protect the retina against the damaging effects of a subsequent 60 min ischemic insult. This phenomenon is called ischemic preconditioning (IPC). To study the changes altered by IPC, we assessed the gene expression patterns in the rat retina after ischemia (60 min) followed by reperfusion (I/R) and compared these to the gene expression patterns after ischemia/reperfusion in preconditioned animals (IPC-I/R).
Changes in gene expression were studied, by means of microarrays, at 1, 2, 6, and 12 h after I/R in naíve and preconditioned animals. To identify functional pathways of interest, we used significantly regulated genes as input for gene ontology analysis. Microarray results were validated by real-time quantitative PCR.
Most genes that were altered by I/R showed a comparable change in both naíve and preconditioned animals. Differential expression was found for a total of 1312 genes of the 20,280 features (6.4%) present on the array with a differential change of 1.7 fold or more. The list of genes with a differential change was characterized by a statistically significant overrepresentation of genes associated to the gene ontology terms tRNA aminoacylation (with a decreased expression due to preconditioning), immune response (with most genes upregulated), and apoptosis (mixed direction of changes). The results of quantitative PCR assays were in agreement with the microarray data.
The response of several functional groups of genes on ischemia was altered by a preconditioning stimulus. Most prominent differences were found for the group of genes encoding for aminoacyl-tRNA synthetases (ARSs), which is in line with the previously observed decreased expression of ARSs after induction of preconditioning. Our observations indicate that activation of translational activity may be a mediator of ischemia-associated damage in the retina, and IPC may prevent activation of this mechanism. An altered expression of genes implicated in immune response and in apoptosis may also be involved in effectuating IPC.
视网膜缺血状态与多种视网膜病变有关。实验诱导的60分钟缺血再灌注会导致视网膜内层神经元丢失。相比之下，5分钟的缺血发作会引发一系列改变，保护视网膜免受随后60分钟缺血损伤的破坏作用。这种现象称为缺血预处理（IPC）。为了研究IPC改变的变化，我们评估了大鼠视网膜在缺血（60分钟）再灌注（I/R）后的基因表达模式，并将其与预处理动物（IPC-I/R）缺血/再灌注后的基因表达模式进行比较。
通过微阵列研究了未预处理和预处理动物在I/R后1、2、6和12小时的基因表达变化。为了确定感兴趣的功能途径，我们使用显著调节的基因作为基因本体分析的输入。微阵列结果通过实时定量PCR进行验证。
I/R改变的大多数基因在未预处理和预处理动物中显示出类似的变化。在阵列上存在的20280个特征中，共有1312个基因（6.4%）存在差异表达，差异变化为1.7倍或更大。差异变化的基因列表的特征是与基因本体术语tRNA氨酰化（由于预处理而表达降低）、免疫反应（大多数基因上调）和细胞凋亡（变化方向混合）相关的基因在统计学上显著过度表达。定量PCR分析结果与微阵列数据一致。
预处理刺激改变了几组基因对缺血的反应。在编码氨酰-tRNA合成酶（ARSs）的基因组中发现了最显著的差异，这与之前观察到的预处理诱导后ARSs表达降低一致。我们的观察结果表明，翻译活性的激活可能是视网膜缺血相关损伤的介质，而IPC可能会阻止这种机制的激活。与免疫反应和细胞凋亡相关的基因表达改变也可能参与实现IPC。
