Department of Biochemical Genetics, Medical Research Institute, Tokyo Medical and Dental University, Tokyo 113-8510, Japan.
J Biol Chem. 2013 Aug 23;288(34):24302-15. doi: 10.1074/jbc.M113.496703. Epub 2013 Jul 3.
Elongin A was shown previously to be capable of potently activating the rate of RNA polymerase II (RNAPII) transcription elongation in vitro by suppressing transient pausing by the enzyme at many sites along DNA templates. The role of Elongin A in RNAPII transcription in mammalian cells, however, has not been clearly established. In this report, we investigate the function of Elongin A in RNAPII transcription. We present evidence that Elongin A associates with the IIO form of RNAPII at sites of newly transcribed RNA and is relocated to dotlike domains distinct from those containing RNAPII when cells are treated with the kinase inhibitor 5,6-dichloro-1-β-d-ribofuranosylbenzimidazole. Significantly, Elongin A is required for maximal induction of transcription of the stress response genes ATF3 and p21 in response to several stimuli. Evidence from structure-function studies argues that Elongin A transcription elongation activity, but not its ubiquitination activity, is most important for its function in induction of transcription of ATF3 and p21. Taken together, our data provide new insights into the function of Elongin A in RNAPII transcription and bring to light a previously unrecognized role for Elongin A in the regulation of stress response genes.
Elongin A 先前被证明能够通过抑制酶在 DNA 模板上的许多位点的瞬时暂停来有效地激活 RNA 聚合酶 II（RNAPII）转录延伸的速率。然而，Elongin A 在哺乳动物细胞中 RNAPII 转录中的作用尚未明确确定。在本报告中，我们研究了 Elongin A 在 RNAPII 转录中的功能。我们提供的证据表明，Elongin A 与新转录 RNA 位点处的 IIO 形式的 RNAPII 相关联，并且在用激酶抑制剂 5,6-二氯-1-β-D-呋喃核糖基苯并咪唑处理细胞时，它被重新定位到与包含 RNAPII 的点不同的点状域。重要的是，Elongin A 是对多种刺激物响应的应激反应基因 ATF3 和 p21 的转录最大诱导所必需的。来自结构功能研究的证据表明，Elongin A 的转录延伸活性，而不是其泛素化活性，对其诱导 ATF3 和 p21 转录的功能最为重要。总之，我们的数据提供了 Elongin A 在 RNAPII 转录中的功能的新见解，并揭示了 Elongin A 在应激反应基因调控中的先前未被认识到的作用。
