Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, People's Republic of China.
Oncogene. 2010 Feb 4;29(5):711-22. doi: 10.1038/onc.2009.372. Epub 2009 Nov 9.
Although Myc-interacting zinc-finger protein-1 (Miz-1) is known to be a poxvirus and zinc-finger (POZ) transcription factor required for Myc transcriptional repression, additional regulatory function of Miz-1 is less well understood. Using a yeast two-hybrid screen, we identified human alternate reading frame (ARF) protein as a novel interaction partner of Miz-1. The zinc-finger domain of Miz-1 is involved in its binding to ARF. In addition, we found that Miz-1 was able to interact with p53 through its DNA-binding domain, thus to diminish the binding of p53 to its target promoter and inhibit p53-mediated gene transcription. Interestingly, the Miz-1-regulated p53 transcriptional suppression does not require the presence of ARF or Mdm2. Importantly, ARF and p53 were found to competitively bind to Miz-1 in regulating p53-mediated transcription, and this conclusion was verified by both in vitro binding assay and competitive chromatin immunoprecipitation assay using a bona fide p53 endogenous Bax and Puma promoters. Thus, our study reveals that Miz-1 acts as a p53 suppressor by interfering with p53 DNA-binding ability, and ARF is able to counteract the suppression of Miz-1 on p53 by direct binding to Miz-1, suggesting that Miz-1 is a novel mediator in the ARF-p53 pathway.
虽然已知 Myc 相互作用锌指蛋白-1（Miz-1）是一种痘病毒和锌指（POZ）转录因子，需要用于 Myc 转录抑制，但对 Miz-1 的其他调节功能了解较少。通过酵母双杂交筛选，我们鉴定出人源交替阅读框（ARF）蛋白是 Miz-1 的一种新的相互作用伙伴。Miz-1 的锌指结构域参与其与 ARF 的结合。此外，我们发现 Miz-1 能够通过其 DNA 结合域与 p53 相互作用，从而减弱 p53 与其靶启动子的结合并抑制 p53 介导的基因转录。有趣的是，Miz-1 调节的 p53 转录抑制不需要 ARF 或 Mdm2 的存在。重要的是，ARF 和 p53 被发现通过调节 p53 介导的转录来竞争结合 Miz-1，这一结论通过体外结合测定和使用真正的 p53 内源性 Bax 和 Puma 启动子的竞争性染色质免疫沉淀测定得到验证。因此，我们的研究表明，Miz-1 通过干扰 p53 DNA 结合能力来作为 p53 抑制剂，而 ARF 能够通过直接结合 Miz-1 来抵消 Miz-1 对 p53 的抑制作用，这表明 Miz-1 是 ARF-p53 通路中的一种新型介质。
