Logan Ian R, Sapountzi Vasileia, Gaughan Luke, Neal David E, Robson Craig N
Northern Institute for Cancer Research, School of Surgical and Reproductive Sciences, Medical School, University of Newcastle, Framlington Place, Newcastle upon Tyne NE2 4HH, United Kingdom.
J Biol Chem. 2004 Mar 19;279(12):11696-704. doi: 10.1074/jbc.M312712200. Epub 2003 Dec 29.
Murine PIRH2 (mPIRH2) was recently identified as a RING finger-containing ubiquitin-protein isopeptide ligase that interacts with both p53 and the human androgen receptor. mpirh2 is a p53-responsive gene that is up-regulated by UV, and mPIRH2 protein has the capacity to polyubiquitylate p53, perhaps leading to p53 destruction. mpirh2 therefore has properties similar to those of the oncogene mdm2. Here, we have identified human PIRH2 (hPIRH2) as a TIP60-interacting protein. To investigate its regulation, we characterized hPIRH2 in parallel with hPIRH2 variants possessing mutations of conserved RING finger residues. We observed that wild-type hPIRH2 is an unstable protein with a short half-life and is a target for RING domain-dependent proteasomal degradation. Accordingly, we found that hPIRH2 was ubiquitylated in cells. The TIP60-hPIRH2 association appeared to regulate hPIRH2 stability; coexpression of TIP60 enhanced hPIRH2 protein stability and altered hPIRH2 subcellular localization. These results suggest that hPIRH2 activities can be controlled, at the post-translational level, in multiple ways.
鼠源PIRH2（mPIRH2）最近被鉴定为一种含RING结构域的泛素蛋白异肽连接酶，它能与p53和人类雄激素受体相互作用。mPIRH2是一个p53反应基因，受紫外线上调，mPIRH2蛋白具有使p53多聚泛素化的能力，这可能导致p53被破坏。因此，mPIRH2具有与癌基因MDM2相似的特性。在这里，我们已鉴定出人类PIRH2（hPIRH2）是一种与TIP60相互作用的蛋白。为了研究其调控机制，我们将hPIRH2与其具有保守RING结构域残基突变的变体同时进行了特性分析。我们观察到野生型hPIRH2是一种不稳定蛋白，半衰期短，是RING结构域依赖性蛋白酶体降解的靶点。相应地，我们发现hPIRH2在细胞中被泛素化。TIP60与hPIRH2的结合似乎调控了hPIRH2的稳定性；TIP60的共表达增强了hPIRH2蛋白的稳定性，并改变了hPIRH2的亚细胞定位。这些结果表明，hPIRH2的活性可以在翻译后水平以多种方式受到调控。
