Laboratorio Nazionale Consorzio Interuniversitario per le Biotecnologie, Area Science Park, 34012 Trieste, Italy.
Proc Natl Acad Sci U S A. 2010 Apr 6;107(14):6322-7. doi: 10.1073/pnas.1002447107. Epub 2010 Mar 22.
The genome of the fruitfly Drosophila melanogaster contains a single p53-like protein, phylogenetically related to the ancestor of the mammalian p53 family of tumor suppressors. We reasoned that a comprehensive map of the protein interaction profile of Drosophila p53 (Dmp53) might help identify conserved interactions of the entire p53 family in man. Using a genome-scale in vitro expression cloning approach, we identified 91 previously unreported Dmp53 interactors, considerably expanding the current Drosophila p53 interactome. Looking for evolutionary conservation of these interactions, we tested 41 mammalian orthologs and found that 37 bound to one or more p53-family members when overexpressed in human cells. An RNAi-based functional assay for modulation of the p53 pathway returned five positive hits, validating the biological relevance of these interactions. One p53 interactor is GTPBP4, a nucleolar protein involved in 60S ribosome biogenesis. We demonstrate that GTPBP4 knockdown induces p53 accumulation and activation in the absence of nucleolar disruption. In breast tumors with wild-type p53, increased expression of GTPBP4 correlates with reduced patient survival, emphasizing a potential relevance of this regulatory axis in cancer.
果蝇（Drosophila melanogaster）的基因组仅包含一种与哺乳动物抑癌基因家族 p53 祖先亲缘关系较近的 p53 样蛋白。我们推断，对果蝇 p53（Dmp53）的蛋白质相互作用图谱进行全面分析，可能有助于确定人类整个 p53 家族的保守相互作用。我们采用基于全基因组体外表达克隆的方法，鉴定出 91 种先前未报道的 Dmp53 相互作用蛋白，极大地扩展了当前的果蝇 p53 相互作用组。为了寻找这些相互作用的进化保守性，我们测试了 41 种哺乳动物直系同源物，发现当在人类细胞中过表达时，其中 37 种与一种或多种 p53 家族成员结合。基于 RNAi 的 p53 通路功能测定返回了 5 个阳性结果，验证了这些相互作用的生物学相关性。一种 p53 相互作用蛋白是 GTPBP4，它是一种参与 60S 核糖体生物发生的核仁蛋白。我们证明，在核仁未被破坏的情况下，GTPBP4 的敲低会诱导 p53 的积累和激活。在野生型 p53 的乳腺癌肿瘤中，GTPBP4 的表达增加与患者生存时间缩短相关，这强调了该调节轴在癌症中的潜在相关性。
