Damgaard Christian Kroun, Kahns Søren, Lykke-Andersen Søren, Nielsen Anders Lade, Jensen Torben Heick, Kjems Jørgen
Centre for mRNP Biogenesis and Metabolism, University of Aarhus, Aarhus, Denmark.
Mol Cell. 2008 Feb 1;29(2):271-8. doi: 10.1016/j.molcel.2007.11.035.
Transcription and pre-mRNA splicing are interdependent events. Although mechanisms governing the effects of transcription on splicing are becoming increasingly clear, the means by which splicing affects transcription remain elusive. Using cell lines stably expressing HIV-1 or beta-globin mRNAs, harboring wild-type or various 5' splice site mutations, we demonstrate a strong positive correlation between splicing efficiency and transcription activity. Interestingly, a 5' splice site can stimulate transcription even in the absence of splicing. Chromatin immunoprecipitation experiments show enhanced promoter docking of transcription initiation factors TFIID, TFIIB, and TFIIH on a gene containing a functional 5' splice site. In addition to their promoter association, the TFIID and TFIIH components, TBP and p89, are specifically recruited to the 5' splice site region. Our data suggest a model in which a promoter-proximal 5' splice site via its U1 snRNA interaction can feed back to stimulate transcription initiation by enhancing pre-initiation complex assembly.
转录和前体mRNA剪接是相互依存的事件。尽管调控转录对剪接影响的机制日益清晰，但剪接影响转录的方式仍不清楚。我们使用稳定表达野生型或各种5'剪接位点突变的HIV-1或β-珠蛋白mRNA的细胞系，证明了剪接效率与转录活性之间存在强正相关。有趣的是，即使在没有剪接的情况下，5'剪接位点也能刺激转录。染色质免疫沉淀实验表明，转录起始因子TFIID、TFIIB和TFIIH在含有功能性5'剪接位点的基因上的启动子对接增强。除了它们与启动子的结合外，TFIID和TFIIH的组分TBP和p89被特异性招募到5'剪接位点区域。我们的数据提出了一个模型，其中启动子近端的5'剪接位点通过其与U1 snRNA的相互作用，可以通过增强起始前复合物的组装反馈来刺激转录起始。
