Percipalle Piergiorgio, Visa Neus
Department of Cell and Molecular Biology, Karolinska Institutet, SE-117 77 Stockholm, Sweden.
J Cell Biol. 2006 Mar 27;172(7):967-71. doi: 10.1083/jcb.200512083. Epub 2006 Mar 20.
Actin is not only a major cytoskeletal component in all eukaryotic cells but also a nuclear protein that plays a role in gene transcription. We put together data from in vitro and in vivo experiments that begin to provide insights into the molecular mechanisms by which actin functions in transcription. Recent studies performed in vitro have suggested that actin, in direct contact with the transcription apparatus, is required in an early step of transcription that is common to all three eukaryotic RNA polymerases. In addition, there is evidence from in vivo studies that actin is involved in the transcription elongation of class II genes. In this case, actin is bound to a specific subset of premessenger RNA binding proteins, and the actin-messenger RNP complex may constitute a molecular platform for recruitment of histone-modifying enzymes. We discuss a general model for actin in RNA polymerase II transcription whereby actin works as a conformational switch in conjunction with specific adaptors to facilitate the remodeling of large macromolecular assemblies at the promoter and along the active gene.
肌动蛋白不仅是所有真核细胞中的主要细胞骨架成分，也是一种在基因转录中起作用的核蛋白。我们整合了来自体外和体内实验的数据，这些数据开始为肌动蛋白在转录中发挥作用的分子机制提供见解。最近的体外研究表明，与转录装置直接接触的肌动蛋白在所有三种真核RNA聚合酶共有的转录早期步骤中是必需的。此外，体内研究有证据表明肌动蛋白参与II类基因的转录延伸。在这种情况下，肌动蛋白与前信使RNA结合蛋白的特定子集结合，并且肌动蛋白-信使核糖核蛋白复合物可能构成募集组蛋白修饰酶的分子平台。我们讨论了肌动蛋白在RNA聚合酶II转录中的一般模型，即肌动蛋白与特定衔接子一起作为构象开关，以促进启动子处和活性基因沿线的大型大分子组装体的重塑。
