Rocha Sonia, Garrett Michelle D, Campbell Kirsteen J, Schumm Katie, Perkins Neil D
School of Life Sciences, Division of Gene Regulation and Expression, University of Dundee, Dundee, Scotland, UK.
EMBO J. 2005 Mar 23;24(6):1157-69. doi: 10.1038/sj.emboj.7600608. Epub 2005 Mar 10.
The ARF tumour suppressor is a central component of the cellular defence against oncogene activation. In addition to activating p53 through binding Mdm2, ARF possesses other functions, including an ability to repress the transcriptional activity of the antiapoptotic RelA(p65) NF-kappaB subunit. Here we demonstrate that ARF induces the ATR- and Chk1-dependent phosphorylation of the RelA transactivation domain at threonine 505, a site required for ARF-dependent repression of RelA transcriptional activity. Consistent with this effect, ATR and Chk1 are required for ARF-induced sensitivity to tumour necrosis factor alpha-induced cell death. Significantly, ATR activity is also required for ARF-induced p53 activity and inhibition of proliferation. ARF achieves these effects by activating ATR and Chk1. Furthermore, ATR and its scaffold protein BRCA1, but not Chk1, relocalise to specific nucleolar sites. These results reveal novel functions for ARF, ATR and Chk1 together with a new pathway regulating RelA NF-kappaB function. Moreover, this pathway provides a mechanism through which ARF can remodel the cellular response to an oncogenic challenge and execute its function as a tumour suppressor.
ARF肿瘤抑制因子是细胞抵御癌基因激活的核心成分。除了通过结合Mdm2激活p53外，ARF还具有其他功能，包括抑制抗凋亡RelA（p65）NF-κB亚基的转录活性的能力。在此，我们证明ARF在苏氨酸505处诱导RelA反式激活结构域的ATR和Chk1依赖性磷酸化，该位点是ARF依赖性抑制RelA转录活性所必需的。与此效应一致，ATR和Chk1是ARF诱导的对肿瘤坏死因子α诱导的细胞死亡敏感性所必需的。重要的是，ATR活性也是ARF诱导的p53活性和增殖抑制所必需的。ARF通过激活ATR和Chk1实现这些效应。此外，ATR及其支架蛋白BRCA1而非Chk1重新定位到特定的核仁位点。这些结果揭示了ARF、ATR和Chk1的新功能以及调节RelA NF-κB功能的新途径。此外，该途径提供了一种机制，通过该机制ARF可以重塑细胞对致癌挑战的反应并执行其作为肿瘤抑制因子的功能。
