Camats Maria, Guil Sonia, Kokolo Mariette, Bach-Elias Montse
Unidad de Splicing, Instituto de Investigaciones Biomédicas de Barcelona-Consejo Superior de Investigaciones Científicas, Barcelona, Spain.
PLoS One. 2008 Aug 13;3(8):e2926. doi: 10.1371/journal.pone.0002926.
H-Ras pre-mRNA undergoes an alternative splicing process to render two proteins, namely p21 H-Ras and p19 H-Ras, due to either the exclusion or inclusion of the alternative intron D exon (IDX), respectively. p68 RNA helicase (p68) is known to reduce IDX inclusion.
Here we show that p68 unwinds the stem-loop IDX-rasISS1 structure and prevents binding of hnRNP H to IDX-rasISS1. We also found that p68 alters the dynamic localization of SC35, a splicing factor that promotes IDX inclusion. The knockdown of hnRNP A1, FUS/TLS and hnRNP H resulted in upregulation of the expression of the gene encoding the SC35-binding protein, SFRS2IP. Finally, FUS/TLS was observed to upregulate p19 expression and to stimulate IDX inclusion, and in vivo RNAi-mediated depletion of hnRNP H decreased p19 H-Ras abundance.
Taken together, p68 is shown to be an essential player in the regulation of H-Ras expression as well as in a vital transduction signal pathway tied to cell proliferation and many cancer processes.
H-Ras前体信使核糖核酸（pre-mRNA）经历选择性剪接过程，分别由于选择性内含子D外显子（IDX）的排除或包含而产生两种蛋白质，即p21 H-Ras和p19 H-Ras。已知p68 RNA解旋酶（p68）可减少IDX的包含。
我们在此表明，p68解开茎环IDX-rasISS1结构，并阻止异质性核糖核蛋白H（hnRNP H）与IDX-rasISS1结合。我们还发现，p68改变了促进IDX包含的剪接因子SC35的动态定位。敲低hnRNP A1、FUS/TLS和hnRNP H导致编码SC355结合蛋白SFRS2IP的基因表达上调。最后，观察到FUS/TLS上调p19表达并刺激IDX包含，并且体内RNA干扰介导的hnRNP H缺失降低了p19 H-Ras丰度。
综上所述，p68被证明是H-Ras表达调控以及与细胞增殖和许多癌症过程相关的重要信号转导途径中的关键参与者。
