Cox-Limpens Kimberly E M, Vles Johan S H, Schlechter Jana, Zimmermann Luc J I, Strackx Eveline, Gavilanes Antonio W D
BMC Neurosci. 2013 Jun 22;14:61. doi: 10.1186/1471-2202-14-61.
Fetal asphyctic (FA) preconditioning is effective in attenuating brain damage incurred by a subsequent perinatal asphyctic insult. Unraveling mechanisms of this endogenous neuroprotection, activated by FA preconditioning, is an important step towards new clinical strategies for asphyctic neonates. Genomic reprogramming is thought to be, at least in part, responsible for the protective effect of preconditioning. Therefore we investigated whole genome differential gene expression in the preconditioned rat brain. FA preconditioning was induced on embryonic day 17 by reversibly clamping uterine circulation. Male control and FA offspring were sacrificed 96 h after FA preconditioning. Whole genome transcription was investigated with Affymetrix Gene1.0ST chip.
Data were analyzed with the Bioconductor Limma package, which showed 53 down-regulated and 35 up-regulated transcripts in the FA-group. We validated these findings with RT-qPCR for adh1, edn1, leptin, rdh2, and smad6. Moreover, we investigated differences in gene expression across different brain regions. In addition, we performed Gene Set Enrichment Analysis (GSEA) which revealed 19 significantly down-regulated gene sets, mainly involved in neurotransmission and ion transport. 10 Gene sets were significantly up-regulated, these are mainly involved in nucleosomal structure and transcription, including genes such as mecp2.
Here we identify for the first time differential gene expression after asphyctic preconditioning in fetal brain tissue, with the majority of differentially expressed transcripts being down-regulated. The observed down-regulation of cellular processes such as neurotransmission and ion transport could represent a restriction in energy turnover which could prevent energy failure and subsequent neuronal damage in an asphyctic event. Up-regulated transcripts seem to exert their function mainly within the cell nucleus, and subsequent Gene Set Enrichment Analysis suggests that epigenetic mechanisms play an important role in preconditioning induced neuroprotection.
胎儿窒息预处理可有效减轻随后围产期窒息性损伤所致的脑损伤。阐明由胎儿窒息预处理激活的这种内源性神经保护机制，是迈向窒息新生儿新临床策略的重要一步。基因组重编程被认为至少部分地负责预处理的保护作用。因此，我们研究了预处理大鼠脑中的全基因组差异基因表达。在胚胎第17天通过可逆性钳夹子宫循环诱导胎儿窒息预处理。在胎儿窒息预处理后96小时处死雄性对照和胎儿窒息后代。用Affymetrix Gene1.0ST芯片研究全基因组转录。
用Bioconductor Limma软件包分析数据，结果显示胎儿窒息组中有53个转录本下调，35个转录本上调。我们用实时定量PCR验证了adh1、edn1、瘦素、rdh2和smad6的这些结果。此外，我们研究了不同脑区基因表达的差异。另外，我们进行了基因集富集分析（GSEA），结果显示有19个基因集显著下调，主要涉及神经传递和离子转运。10个基因集显著上调，主要涉及核小体结构和转录，包括mecp2等基因。
在此我们首次鉴定了胎儿脑组织窒息预处理后的差异基因表达，大多数差异表达的转录本下调。观察到的神经传递和离子转运等细胞过程的下调可能代表能量转换的限制，这可以防止窒息事件中的能量衰竭和随后的神经元损伤。上调的转录本似乎主要在细胞核内发挥作用，随后的基因集富集分析表明表观遗传机制在预处理诱导的神经保护中起重要作用。
