title: Influenza A Virus-Induced Expression of a GalNAc Transferase, GALNT3, via MicroRNAs Is Required for Enhanced Viral Replication.
abstract: Influenza A virus (IAV) affects the upper and lower respiratory tracts and rapidly induces the expression of mucins, which are common O-glycosylated proteins, on the epithelial surfaces of the respiratory tract. Although mucin production is associated with the inhibition of virus transmission as well as characteristic clinical symptoms, little is known regarding how mucins are produced on the surfaces of respiratory epithelial cells and how they affect IAV replication. In this study, we found that two microRNAs (miRNAs), miR-17-3p and miR-221, which target GalNAc transferase 3 (GALNT3) mRNA, are rapidly downregulated in human alveolar basal epithelial cells during the early stage of IAV infection. We demonstrated that the expression of GALNT3 mRNA is upregulated in an IAV replication-dependent fashion and leads to mucin production in bronchial epithelial cells. A lectin microarray analysis revealed that the stable expression of GALNT3 by human alveolar basal epithelial cells induces mucin-type O-glycosylation modifications similar to those present in IAV-infected cells, suggesting that GALNT3 promotes mucin-type O-linked glycosylation in IAV-infected cells. Notably, analyses using short interfering RNAs and miRNA mimics showed that GALNT3 knockdown significantly reduces IAV replication. Furthermore, IAV replication was markedly decreased in embryonic fibroblast cells obtained from galnt3-knockout mice. Interestingly, IAV-infected galnt3-knockout mice exhibited high mortality and severe pathological alterations in the lungs compared to those of wild-type mice. Our results demonstrate not only the molecular mechanism underlying rapid mucin production during IAV infection but also the contribution of O-linked glycosylation to the replication and propagation of IAV in lung cells.
  
  
  OBJECTIVE
  Viral infections that affect the upper or lower respiratory tracts, such as IAV, rapidly induce mucin production on the epithelial surfaces of respiratory cells. However, the details of how mucin-type O-linked glycosylation is initiated by IAV infection and how mucin production affects viral replication have not yet been elucidated. In this study, we show that levels of two miRNAs that target the UDP-GalNAc transferase GALNT3 are markedly decreased during the early stage of IAV infection, resulting in the upregulation of GALNT3 mRNA. We also demonstrate that the expression of GALNT3 initiates mucin production and affects IAV replication in infected cells. This is the first report demonstrating the mechanism underlying the miRNA-mediated initiation of mucin-type O-glycosylation in IAV-infected cells and its role in viral replication. Our results have broad implications for understanding IAV replication and suggest a strategy for the development of novel anti-influenza approaches.
authors.affiliation: Department of Viral Oncology, Institute for Virus Research, Kyoto University, Kyoto, Japan Department of Tumor Viruses, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Shoko
authors.initials: S
authors.lastname: Nakamura
authors.affiliation: Department of Viral Oncology, Institute for Virus Research, Kyoto University, Kyoto, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Horie
authors.affiliation: Department of Infectious Diseases, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Tomo
authors.initials: T
authors.lastname: Daidoji
authors.affiliation: Department of Viral Oncology, Institute for Virus Research, Kyoto University, Kyoto, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Honda
authors.affiliation: Laboratory of Veterinary Public Health, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Osaka, Japan.
authors.forename: Mayo
authors.initials: M
authors.lastname: Yasugi
authors.affiliation: Research Center for Medical Glycoscience, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kuno
authors.affiliation: Department of Cell Biology, Unit of Basic Medical Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Komori
authors.affiliation: DNA-Chip Development Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Okuzaki
authors.affiliation: Research Center for Medical Glycoscience, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Narimatsu
authors.affiliation: Laboratory of Veterinary Public Health, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Osaka, Japan.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Nakaya
authors.affiliation: Department of Viral Oncology, Institute for Virus Research, Kyoto University, Kyoto, Japan Department of Tumor Viruses, Graduate School of Medicine, Kyoto University, Kyoto, Japan Department of Mammalian Regulatory Network, Graduate School of Biostudies, Kyoto University, Kyoto, Japan tomonaga@virus.kyoto-u.ac.jp.
authors.forename: Keizo
authors.initials: K
authors.lastname: Tomonaga
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000201:enzymology / Q000821:virology; D005260:Female; D015870:Gene Expression; D054884:Host-Pathogen Interactions; D006801:Humans; D009980:Influenza A virus / Q000502:physiology*; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D035683:MicroRNAs / Q000378:metabolism*; D017350:N-Acetylgalactosaminyltransferases / Q000096:biosynthesis*; D014779:Virus Replication; D000097763:Polypeptide N-acetylgalactosaminyltransferase
chemical_list: D035683:MicroRNAs; D017350:N-Acetylgalactosaminyltransferases; D000097763:Polypeptide N-acetylgalactosaminyltransferase