Chen Yexi, Yamaguchi Yuki, Tsugeno Yuta, Yamamoto Junichi, Yamada Tomoko, Nakamura Mitsuhiro, Hisatake Koji, Handa Hiroshi
Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama 226-8501, Japan.
Genes Dev. 2009 Dec 1;23(23):2765-77. doi: 10.1101/gad.1834709.
Transcription elongation factor DSIF/Spt4-Spt5 is capable of promoting and inhibiting RNA polymerase II elongation and is involved in the expression of various genes. While it has been known for many years that DSIF inhibits elongation in collaboration with the negative elongation factor NELF, how DSIF promotes elongation is largely unknown. Here, an activity-based biochemical approach was taken to understand the mechanism of elongation activation by DSIF. We show that the Paf1 complex (Paf1C) and Tat-SF1, two factors implicated previously in elongation control, collaborate with DSIF to facilitate efficient elongation. In human cells, these factors are recruited to the FOS gene in a temporally coordinated manner and contribute to its high-level expression. We also show that elongation activation by these factors depends on P-TEFb-mediated phosphorylation of the Spt5 C-terminal region. A clear conclusion emerging from this study is that a set of elongation factors plays nonredundant, cooperative roles in elongation. This study also shows unambiguously that Paf1C, which is generally thought to have chromatin-related functions, is involve directlyd in elongation control.
转录延伸因子DSIF/Spt4-Spt5既能促进也能抑制RNA聚合酶II的延伸，且参与多种基因的表达。虽然多年来已知DSIF与负性延伸因子NELF协同抑制延伸，但DSIF如何促进延伸在很大程度上尚不清楚。在此，我们采用基于活性的生化方法来了解DSIF激活延伸的机制。我们发现，Paf1复合物（Paf1C）和Tat-SF1这两个先前与延伸控制有关的因子，与DSIF协同作用以促进高效延伸。在人类细胞中，这些因子以时间协调的方式被招募到FOS基因，并促进其高水平表达。我们还表明，这些因子激活延伸依赖于P-TEFb介导的Spt5 C末端区域的磷酸化。这项研究得出的一个明确结论是，一组延伸因子在延伸过程中发挥着非冗余的协同作用。这项研究还明确表明，通常认为具有染色质相关功能的Paf1C直接参与延伸控制。
