Chatterjee Aditi, Mambo Elizabeth, Osada Motonobu, Upadhyay Sunil, Sidransky David
Department of Otolaryngology-Head and Neck Surgery, Head and Neck Cancer Research Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2196, USA.
FASEB J. 2006 Jan;20(1):112-4. doi: 10.1096/fj.04-3423fje. Epub 2005 Nov 17.
Recent evidence indicates that in vitro p53 augments base excision repair (BER) activities in mammalian cells. To understand the role of p53 in BER, we analyzed the repair activity of hOgg1 in isogenic cell lines HCT116p53+/+ and HCT116p53-/-. We found that hOgg1 activity was significantly decreased in HCT116p53-/- cells as compared with HCT116p53+/+ cells, indicating a functional role for p53 in the regulation of hOGG1. Using gel-shift assays, we showed that p53 binds to its putative cis-elements within the hOGG1 promoter. In addition we demonstrated that supplementing p53 in HCT116p53-/- cells enhanced the transcription of hOGG1. To further strengthen our findings, we used p53-RNAi to study the effects of decreased p53 levels on hOgg1 activity. We observed that p53-RNAi resulted in decreased hOGG1 expression both at the mRNA and protein levels. This decrease in hOGG1 expression was associated with reduced cell viability upon oxidative damage and reduced hOgg1 activity as evidenced by the 8-oxoG incision assay. Taken together, our results indicate that loss of p53 function can lead to decreased hOgg1 repair activity.
最近的证据表明，体外实验中p53可增强哺乳动物细胞中的碱基切除修复（BER）活性。为了解p53在BER中的作用，我们分析了同基因细胞系HCT116p53+/+和HCT116p53-/-中hOgg1的修复活性。我们发现，与HCT116p53+/+细胞相比，HCT116p53-/-细胞中的hOgg1活性显著降低，这表明p53在hOGG1的调节中具有功能性作用。通过凝胶迁移实验，我们表明p53与其在hOGG1启动子内的假定顺式元件结合。此外，我们证明在HCT116p53-/-细胞中补充p53可增强hOGG1的转录。为了进一步加强我们的发现，我们使用p53-RNAi来研究p53水平降低对hOgg1活性的影响。我们观察到p53-RNAi导致hOGG1在mRNA和蛋白质水平上的表达均降低。hOGG1表达的这种降低与氧化损伤后细胞活力降低以及hOgg1活性降低有关，8-氧代鸟嘌呤切口实验证明了这一点。综上所述，我们的结果表明p53功能丧失可导致hOgg1修复活性降低。
