title: The splicing factor proline-glutamine rich (SFPQ/PSF) is involved in influenza virus transcription.
abstract: The influenza A virus RNA polymerase is a heterotrimeric complex responsible for viral genome transcription and replication in the nucleus of infected cells. We recently carried out a proteomic analysis of purified polymerase expressed in human cells and identified a number of polymerase-associated cellular proteins. Here we characterise the role of one such host factors, SFPQ/PSF, during virus infection. Down-regulation of SFPQ/PSF by silencing with two independent siRNAs reduced the virus yield by 2-5 log in low-multiplicity infections, while the replication of unrelated viruses as VSV or Adenovirus was almost unaffected. As the SFPQ/PSF protein is frequently associated to NonO/p54, we tested the potential implication of the latter in influenza virus replication. However, down-regulation of NonO/p54 by silencing with two independent siRNAs did not affect virus yields. Down-regulation of SFPQ/PSF by siRNA silencing led to a reduction and delay of influenza virus gene expression. Immunofluorescence analyses showed a good correlation between SFPQ/PSF and NP levels in infected cells. Analysis of virus RNA accumulation in silenced cells showed that production of mRNA, cRNA and vRNA is reduced by more than 5-fold but splicing is not affected. Likewise, the accumulation of viral mRNA in cicloheximide-treated cells was reduced by 3-fold. In contrast, down-regulation of SFPQ/PSF in a recombinant virus replicon system indicated that, while the accumulation of viral mRNA is reduced by 5-fold, vRNA levels are slightly increased. In vitro transcription of recombinant RNPs generated in SFPQ/PSF-silenced cells indicated a 4-5-fold reduction in polyadenylation but no alteration in cap snatching. These results indicate that SFPQ/PSF is a host factor essential for influenza virus transcription that increases the efficiency of viral mRNA polyadenylation and open the possibility to develop new antivirals targeting the accumulation of primary transcripts, a very early step during infection.
authors: Centro Nacional de Biotecnología, CSIC, Campus de Cantoblanco, Madrid, Spain.
authors: Sara
authors: S
authors: Landeras-Bueno
authors: Núria
authors: N
authors: Jorba
authors: Maite
authors: M
authors: Pérez-Cidoncha
authors: Juan
authors: J
authors: Ortín
mesh_terms: D045744:Cell Line, Tumor; D015536:Down-Regulation; D057809:HEK293 Cells; D006801:Humans; D009980:Influenza A virus / Q000235:genetics / Q000502:physiology*; D007700:Kinetics; D000072670:PTB-Associated Splicing Factor; D026723:Polyadenylation; D034622:RNA Interference; D012326:RNA Splicing; D012367:RNA, Viral / Q000378:metabolism; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins / Q000378:metabolism; D014779:Virus Replication / Q000235:genetics*
chemical_list: D000072670:PTB-Associated Splicing Factor; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins