RETRACTED ARTICLE: Phosphor-IWS1-dependent U2AF2 splicing regulates trafficking of CAR-E-positive intronless gene mRNAs and sensitivity to viral infection

Georgios I Laliotis,Vollter Anastas,Evangelia Chavdoula,Joal D Beane,Lalit Sehgal,Jacob S Yount,Philip N Tsichlis,Arturo Orlacchio,Christos Tsatsanis,Vincenzo Coppola,Abdul Kaba,Adam D Kenney,Alessandro La Ferlita

doi:10.1038/s42003-021-02668-z

Abstract

AKT-phosphorylated IWS1 promotes Histone H3K36 trimethylation and alternative RNA splicing of target genes, including the U2AF65 splicing factor-encoding U2AF2. The predominant U2AF2 transcript, upon IWS1 phosphorylation block, lacks the RS-domain-encoding exon 2, and encodes a protein which fails to bind Prp19. Here we show that although both U2AF65 isoforms bind intronless mRNAs containing cytoplasmic accumulation region elements (CAR-E), only the RS domain-containing U2AF65 recruits Prp19 and promotes their nuclear export. The loading of U2AF65 to CAR-Elements was RS domain-independent, but RNA PolII-dependent. Virus- or poly(I:C)-induced type I IFNs are encoded by genes targeted by the pathway. IWS1 phosphorylation-deficient cells therefore, express reduced levels of IFNα1/IFNβ1 proteins, and exhibit enhanced sensitivity to infection by multiple cytolytic viruses. Enhanced sensitivity of IWS1-deficient cells to Vesicular Stomatitis Virus and Reovirus resulted in enhanced apoptotic cell death via caspase activation. Inhibition of this pathway may therefore sensitize cancer cells to oncolytic viruses.

Highlights

AKT-phosphorylated IWS1 promotes Histone H3K36 trimethylation and alternative RNA splicing of target genes, including the U2AF65 splicing factor-encoding U2 Associated-Factor 2 (U2AF2)
Inhibition of the pathway sensitized the cells to a broad array of viruses, including Vesicular Stomatitis Virus (VSV), Influenza virus, Sendai virus and Reovirus
It had been shown that the mRNAs of the majority of naturally intronless genes, including type I IFNs, JUN and HSPB3, contain 10 nucleotide consensus CAR-Elements, which provide the docking site for the assembly of nucleocytoplasmic export complexes, containing members of the TREX complex, U2AF65 and Prp[19]

Summary

Introduction

AKT-phosphorylated IWS1 promotes Histone H3K36 trimethylation and alternative RNA splicing of target genes, including the U2AF65 splicing factor-encoding U2AF2. Phosphorylation of IWS1 by AKT3 and AKT1 promotes the inclusion of this exon 2 in the mature U2AF2 mRNA transcript This exon encodes part of the RS domain of U2AF65, which is required for U2AF65 binding to Prp[19], a member of a seven-member protein complex (PRP19C), with ubiquitin ligase activity, which is involved in RNA splicing. This pathway is cell cycle regulated and some of its target genes are regulators of the cell cycle. This could potentially change by targeting type I IFN signaling and altering the sensitivity of the tumor cells to infection by such viruses

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Conclusion