Miele Angela, Medina Ricardo, van Wijnen Andre J, Stein Gary S, Stein Janet L
Department of Cell Biology and Cancer Center, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA.
J Cell Biochem. 2007 Sep 1;102(1):136-48. doi: 10.1002/jcb.21284.
HiNF-P is a recently identified histone H4 subtype specific transcriptional regulator that associates with the conserved cell cycle control element in the proximal promoter regions of histone H4 genes. HiNF-P interacts with the global histone gene regulator and direct cyclin E/CDK2 substrate p220(NPAT) to potently upregulate histone H4 gene transcription at the G1/S phase transition in response to cyclin E/CDK2 signaling. To gain insight into the function of HiNF-P in a broader cellular context, we performed a yeast two-hybrid screen to identify its novel interacting proteins. In this study, we detected 67 candidate HiNF-P interacting proteins of varying cellular functions. We have identified multiple RNA associated proteins, including the splicing co-factor SRm300. HiNF-P and SRm300 interact in yeast two-hybrid, co-immunoprecipitation, and co-immunofluorescence assays. Our screen also identified several gene regulators that associate with HiNF-P including THAP7. HiNF-P and THAP7 interact in mammalian cells and THAP7 abrogates HiNF-P/p220 mediated activation of histone H4 gene transcription, consistent with its known role as a transcriptional repressor. Finally, we identified several proliferation related proteins including Ki-67 and X transactivated protein 2 (XTP2) which may be functioning with HiNF-P in cell cycle regulation. The HiNF-P interactome indicates that HiNF-P is a multifunctional gene regulator with a large functional network and roles beyond cell cycle-dependent histone gene regulation.
HiNF-P是一种最近发现的组蛋白H4亚型特异性转录调节因子，它与组蛋白H4基因近端启动子区域中保守的细胞周期控制元件相关联。HiNF-P与全局组蛋白基因调节因子相互作用，并直接与细胞周期蛋白E/细胞周期蛋白依赖性激酶2（CDK2）的底物p220（NPAT）相互作用，以响应细胞周期蛋白E/CDK2信号，在G1/S期转换时有力地上调组蛋白H4基因转录。为了更深入了解HiNF-P在更广泛细胞环境中的功能，我们进行了酵母双杂交筛选以鉴定其新的相互作用蛋白。在本研究中，我们检测到67种具有不同细胞功能的候选HiNF-P相互作用蛋白。我们鉴定出了多种与RNA相关的蛋白，包括剪接辅因子SRm300。HiNF-P和SRm300在酵母双杂交、共免疫沉淀和共免疫荧光试验中相互作用。我们的筛选还鉴定出了几种与HiNF-P相关的基因调节因子，包括THAP7。HiNF-P和THAP7在哺乳动物细胞中相互作用，并且THAP7消除了HiNF-P/p220介导的组蛋白H4基因转录激活，这与其作为转录抑制因子的已知作用一致。最后，我们鉴定出了几种与增殖相关的蛋白，包括Ki-67和X反式激活蛋白2（XTP2），它们可能在细胞周期调节中与HiNF-P共同发挥作用。HiNF-P相互作用组表明HiNF-P是一种多功能基因调节因子，具有庞大的功能网络，其作用不仅仅局限于细胞周期依赖性组蛋白基因调节。
