Wellcome Trust Centre for Cell Biology, Institute for Cell Biology, University of Edinburgh Michael Swann Building, King's Buildings, Mayfield Road, Edinburgh EH9 3JR, United Kingdom.
Nucleic Acids Res. 2013 Aug;41(14):7101-14. doi: 10.1093/nar/gkt446. Epub 2013 May 28.
Splicing of human pre-mRNA is reciprocally coupled to 3' end formation by terminal exon definition, which occurs co-transcriptionally. It is required for the final maturation of most human pre-mRNAs and is therefore important to understand. We have used several strategies to block splicing at specific stages in vivo and studied their effect on 3' end formation. We demonstrate that a terminal splice acceptor site is essential to establish coupling with the poly(A) signal in a chromosomally integrated β-globin gene. This is in part to alleviate the suppression of 3' end formation by U1 small nuclear RNA, which is known to bind pre-mRNA at the earliest stage of spliceosome assembly. Interestingly, blocks to splicing that are subsequent to terminal splice acceptor site function, but before catalysis, have little observable effect on 3' end formation. These data suggest that early stages of spliceosome assembly are sufficient to functionally couple splicing and 3' end formation, but that on-going intron removal is less critical.
人类前 mRNA 的剪接与 3' 末端形成是相互偶联的，由末端外显子定义，这一过程发生在转录过程中。它是大多数人类前 mRNA 最终成熟所必需的，因此理解这一过程非常重要。我们使用了几种策略在体内阻断特定阶段的剪接，并研究了它们对 3' 末端形成的影响。我们证明，在染色体整合的β-珠蛋白基因中，一个末端剪接接受位点对于与 poly(A) 信号建立偶联是至关重要的。这在一定程度上缓解了 U1 小核 RNA 对 3' 末端形成的抑制作用，众所周知，U1 小核 RNA 在剪接体组装的最早阶段与前 mRNA 结合。有趣的是，在末端剪接接受位点功能之后但在催化之前发生的剪接阻断对 3' 末端形成几乎没有明显影响。这些数据表明，剪接体组装的早期阶段足以使剪接和 3' 末端形成功能偶联，但持续的内含子去除不太关键。
