Dipartimento di Biochimica e Biotecnologie Mediche, Università Federico II, Napoli, Italy.
Nucleic Acids Res. 2011 Sep 1;39(17):7576-85. doi: 10.1093/nar/gkr461. Epub 2011 Jun 25.
Alternative pre-mRNA splicing (AS) is a major mechanism that allows proteomic variability in eukaryotic cells. However, many AS events result in mRNAs containing a premature termination codon, which are degraded by nonsense-mediated mRNA decay (NMD) pathway. We have previously demonstrated that human rpL3 autoregulates its expression through the association of AS with NMD. In fact, overexpression of rpL3 promotes downregulation of canonical splicing and upregulation of alternative splicing that produces an NMD-targeted mRNA isoform. The result of these events is a decreased production of rpL3. We have also identified heterogeneous nuclear ribonucleoprotein (hnRNP) H1 as a splicing factor involved in the regulation of rpL3 alternative splicing and identified its regulatory cis-elements within intron 3 transcript. Here, we report that NPM and KHSRP are two newly identified proteins involved in the regulation of rpL3 gene expression via AS-NMD. We demonstrate that hnRNP H1, KHSRP and NPM can be found associated, and present also in ribonucleoproteins (RNPs) including rpL3 and intron 3 RNA in vivo, and describe protein-protein and RNA-protein interactions. Moreover, our data provide an insight on the crucial role of hnRNP H1 in the regulation of the alternative splicing of the rpL3 gene.
可变剪接是真核细胞产生蛋白质组多样性的主要机制。然而，许多可变剪接事件导致含有提前终止密码子的 mRNA，这些 mRNA 会被无义介导的 mRNA 降解（NMD）途径降解。我们之前已经证明，人类 rpL3 通过与 NMD 的关联来自我调节其表达。事实上，rpL3 的过表达会促进规范剪接的下调和替代剪接的上调，从而产生针对 NMD 的 mRNA 异构体。这些事件的结果是 rpL3 的产量减少。我们还鉴定了异质核核糖核蛋白 (hnRNP) H1 作为参与 rpL3 可变剪接调节的剪接因子，并鉴定了其 3 号内含子转录本中的调节顺式元件。在这里，我们报告 NPM 和 KHSRP 是两个新鉴定的蛋白质，通过 AS-NMD 参与 rpL3 基因表达的调节。我们证明 hnRNP H1、KHSRP 和 NPM 可以结合，并且还存在于体内包括 rpL3 和 3 号内含子 RNA 的核糖核蛋白 (RNP) 中，并描述了蛋白质-蛋白质和 RNA-蛋白质相互作用。此外，我们的数据提供了 hnRNP H1 在调节 rpL3 基因的可变剪接中起关键作用的见解。
