CWC22 connects pre-mRNA splicing and exon junction complex assembly.
CWC22 connects pre-mRNA splicing and exon junction complex assembly.
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DOI：
10.1016/j.celrep.2012.08.017
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发表时间：
2012-09
期刊：
影响因子：
8.8
通讯作者：
Anna-Lena Steckelberg;Volker Boehm;A. Gromadzka;Niels H. Gehring
中科院分区：
文献类型：
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作者：
Anna-Lena Steckelberg;Volker Boehm;A. Gromadzka;Niels H. Gehring
外显子连接复合物 (EJC) 是转录后 mRNA 命运的关键调节因子，并在剪接过程中与 mRNA 结合。尽管 EJC 的组成已被充分了解，但介导剪接依赖性 EJC 组装的机制和招募 EJC 的因子仍然难以捉摸。在这里，我们将 CWC22 确定为 EJC 组装所需的重要拼接因子。在 CWC22 耗尽的细胞中，前 mRNA 剪接受损，但由 CWC22 的中心片段挽救。我们表明，CWC22 的 MIF4G 结构域通过与 EJC 核心蛋白 eIF4A3 直接相互作用启动 EJC 组装，并且我们表征了 eIF4A3 中废除与 CWC22 结合的突变。这些 eIF4A3 突变体有效地使不依赖剪接的重组 EJC 核心复合物成核，但它们无法支持剪接依赖的 EJC 沉积。我们的工作在剪接机制和 EJC 之间建立了直接联系，从而揭示了转录后基因调控网络中心的分子相互作用。
The exon junction complex (EJC) is a key regulator of posttranscriptional mRNA fate and binds to mRNA during splicing. Although the composition of EJCs is well understood, the mechanism mediating splicing-dependent EJC assembly and the factor(s) recruiting the EJC remain elusive. Here, we identify CWC22 as an essential splicing factor that is required for EJC assembly. In CWC22-depleted cells, pre-mRNA splicing is impaired but is rescued by a central fragment of CWC22. We show that the MIF4G domain of CWC22 initiates EJC assembly via a direct interaction with the EJC core protein eIF4A3, and we characterize mutations in eIF4A3 that abolish binding to CWC22. These eIF4A3 mutants efficiently nucleate splicing-independent recombinant EJC core complexes, but they fail to support splicing-dependent EJC deposition. Our work establishes a direct link between the splicing machinery and the EJC, hence uncovering a molecular interaction at the center of a posttranscriptional gene regulation network.