Release of severe acute respiratory syndrome coronavirus nuclear import block enhances host transcription in human lung cells.
The severe acute respiratory syndrome coronavirus accessory protein ORF6 antagonizes interferon signaling by blocking karyopherin-mediated nuclear import processes. Viral nuclear import antagonists, expressed by several highly pathogenic RNA viruses, likely mediate pleiotropic effects on host gene expression, presumably interfering with transcription factors, cytokines, hormones, and/or signaling cascades that occur in response to infection. By bioinformatic and systems biology approaches, we evaluated the impact of nuclear import antagonism on host expression networks by using human lung epithelial cells infected with either wild-type virus or a mutant that does not express ORF6 protein. Microarray analysis revealed significant changes in differential gene expression, with approximately twice as many upregulated genes in the mutant virus samples by 48 h postinfection, despite identical viral titers. Our data demonstrated that ORF6 protein expression attenuates the activity of numerous karyopherin-dependent host transcription factors (VDR, CREB1, SMAD4, p53, EpasI, and Oct3/4) that are critical for establishing antiviral responses and regulating key host responses during virus infection. Results were confirmed by proteomic and chromatin immunoprecipitation assay analyses and in parallel microarray studies using infected primary human airway epithelial cell cultures. The data strongly support the hypothesis that viral antagonists of nuclear import actively manipulate host responses in specific hierarchical patterns, contributing to the viral pathogenic potential in vivo. Importantly, these studies and modeling approaches not only provide templates for evaluating virus antagonism of nuclear import processes but also can reveal candidate cellular genes and pathways that may significantly influence disease outcomes following severe acute respiratory syndrome coronavirus infection in vivo.
Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA. sims0018@ad.unc.edu
Amy C
AC
Sims
Susan C
SC
Tilton
Vineet D
VD
Menachery
Lisa E
LE
Gralinski
Alexandra
A
Schäfer
Melissa M
MM
Matzke
Bobbie-Jo M
BJ
Webb-Robertson
Jean
J
Chang
Maria L
ML
Luna
Casey E
CE
Long
Anil K
AK
Shukla
Armand R
AR
Bankhead
Susan E
SE
Burkett
Gregory
G
Zornetzer
Chien-Te Kent
CT
Tseng
Thomas O
TO
Metz
Raymond
R
Pickles
Shannon
S
McWeeney
Richard D
RD
Smith
Michael G
MG
Katze
Katrina M
KM
Waters
Ralph S
RS
Baric
D021581:Active Transport, Cell Nucleus / Q000502:physiology; D047369:Chromatin Immunoprecipitation; D019295:Computational Biology / Q000379:methods; D017931:DNA Primers / Q000235:genetics; D004847:Epithelial Cells / Q000378:metabolism / Q000821:virology; D053263:Gene Regulatory Networks / Q000502:physiology*; D006801:Humans; D008168:Lung / Q000166:cytology; D046228:Microarray Analysis; D040901:Proteomics; D060888:Real-Time Polymerase Chain Reaction; D045473:Severe acute respiratory syndrome-related coronavirus / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D049490:Systems Biology / Q000379:methods; D014158:Transcription, Genetic / Q000502:physiology*; D054334:Viral Regulatory and Accessory Proteins / Q000378:metabolism*
D017931:DNA Primers; D054334:Viral Regulatory and Accessory Proteins