Human Staufen1 protein interacts with influenza virus ribonucleoproteins and is required for efficient virus multiplication.
The influenza A virus genome consists of 8 negative-stranded RNA segments. NS1 is a nonstructural protein that participates in different steps of the virus infectious cycle, including transcription, replication, and morphogenesis, and acts as a virulence factor. Human Staufen1 (hStau1), a protein involved in the transport and regulated translation of cellular mRNAs, was previously identified as a NS1-interacting factor. To investigate the possible role of hStau1 in the influenza virus infection, we characterized the composition of hStau1-containing granules isolated from virus-infected cells. Viral NS1 protein and ribonucleoproteins (RNPs) were identified in these complexes by Western blotting, and viral mRNAs and viral RNAs (vRNAs) were detected by reverse transcription (RT)-PCR. Also, colocalization of hStau1 with NS1, nucleoprotein (NP), and PA in the cytosol of virus-infected cells was shown by immunofluorescence. To analyze the role of hStau1 in the infection, we downregulated its expression by gene silencing. Human HEK293T cells or A549 cells were silenced using either short hairpin RNAs (shRNAs) or small interfering RNAs (siRNAs) targeting four independent sites in the hStau1 mRNA. The yield of influenza virus was reduced 5 to 10 times in the various hStau1-silenced cells compared to that in control silenced cells. The expression levels of viral proteins and their nucleocytoplasmic localization were not affected upon hStau1 silencing, but virus particle production, as determined by purification of virions from supernatants, was reduced. These results indicate a role for hStau1 in late events of the influenza virus infection, possibly during virus morphogenesis.
de Lucas
Susana
S
Department of Molecular and Cellular Biology, Centro Nacional Biotecnología (CSIC) and CIBER de Enfermedades Respiratorias (ISCIII), Darwin 3, Campus Cantoblanco, Madrid, Spain.
Peredo
Joan
J
Marión
Rosa María
RM
Sánchez
Carmen
C
Ortín
Juan
J
D015153:Blotting, Western; D002460:Cell Line; D003598:Cytoskeletal Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020868:Gene Silencing; D054884:Host-Pathogen Interactions; D006801:Humans; D009980:Influenza A virus / Q000254:growth & development / Q000502:physiology*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D012333:RNA, Messenger / Q000378:metabolism; D012367:RNA, Viral / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012261:Ribonucleoproteins / Q000378:metabolism*; D014764:Viral Proteins / Q000378:metabolism*; D014779:Virus Replication
D003598:Cytoskeletal Proteins; D012333:RNA, Messenger; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; C492185:STAU1 protein, human; D014764:Viral Proteins