Department of Animal and Human Physiology, School of Biology, Faculty of Sciences, University of Athens, Athens, Greece.
Physiol Res. 2010;59(3):443-454. doi: 10.33549/physiolres.931806. Epub 2009 Aug 12.
One of the most significant insults that jeopardize cardiomyocyte homeostasis is a surge of reactive oxygen species (ROS) in the failing myocardium. Early growth response factor-1 (Egr-1) has been found to act as a transcriptional regulator in multiple biological processes known to exert deleterious effects on cardiomyocytes. We thus investigated the signaling pathways involved in its regulation by H2O2. Egr-1 mRNA levels were found to be maximally induced after 2 h in H2O2-treated H9c2 cells. Egr-1 respective response at the protein level, was found to be maximally induced after 2 h of treatment with 200 microM H2O2, remaining elevated for 6 h, and declining thereafter. H2O2-induced upregulation of Egr-1 mRNA and protein levels was ablated in the presence of agents inhibiting ERKs pathway (PD98059) and JNKs (SP600125, AS601245). Immunofluorescent experiments revealed H2O2-induced Egr-1 nuclear sequestration to be also ERK- and JNK-dependent. Overall, our results show for the first time the fundamental role of ERKs and JNKs in regulating Egr-1 response to H2O2 treatment in cardiac cells at multiple levels: mRNA, protein and subcellular distribution. Nevertheless, further studies are required to elucidate the specific physiological role of Egr-1 regarding the modulation of gene expression and determination of cell fate.
一种危害心肌细胞稳态的重要损伤是活性氧簇（ROS）在衰竭心肌中的爆发。早期生长反应因子-1（Egr-1）已被发现作为多种生物过程的转录调节因子，这些过程已知对心肌细胞有有害影响。因此，我们研究了其受 H2O2 调节的信号通路。发现 H2O2 处理的 H9c2 细胞中，Egr-1mRNA 水平在 2 小时后最大程度诱导。在 200μM H2O2 处理 2 小时后，发现 Egr-1 相应的蛋白水平最大程度诱导，持续升高 6 小时，然后下降。在存在抑制 ERKs 途径（PD98059）和 JNKs（SP600125、AS601245）的药物存在下，H2O2 诱导的 Egr-1mRNA 和蛋白水平的上调被消除。免疫荧光实验显示，H2O2 诱导的 Egr-1 核隔离也依赖于 ERK 和 JNK。总之，我们的研究结果首次表明，在多个水平上，ERK 和 JNK 在调节 Egr-1 对 H2O2 处理的反应中起着重要作用：mRNA、蛋白和亚细胞分布。然而，需要进一步的研究来阐明 Egr-1 关于基因表达的调节和细胞命运的决定的具体生理作用。
