Expression of importin-α isoforms in human nasal mucosa: implication for adaptation of avian influenza A viruses to human host.
BACKGROUND
Transportation into the host cell nucleus is crucial for replication and transcription of influenza virus. The classical nuclear import is regulated by specific cellular factor, importin-α. Seven isoforms of importin-α have been identified in human. The preference of importin-α3 of avian influenza virus and -α7 isoform of human strains during replication in human cells was previously identified. In addition, both avian and human influenza viruses were shown to use importin-α1 isoform for their replication.


RESULTS
The mRNA levels of importin-α1, -α3, and -α7 isoforms in human respiratory tract was determined by real-time RT-PCR. The results indicate that mRNA level of importin-α7 was significantly higher than that of importin-α1 (p-value < 0.0001) and importin-α3 (p-value < 0.0001) isoforms in human nasal mucosa while importin-α1 was detected as the highest expression importin-α isoform in lung tissues.


CONCLUSIONS
These results may explain the preference of importin-α7 isoforms in seasonal influenza viruses in human upper respiratory tract and may suggest a selective pressure toward importin-α7 in human respiratory tract infection of an avian virus.
Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand.
Khwansiri
K
Ninpan
Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand.
Ornpreya
O
Suptawiwat
Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand.
Chompunuch
C
Boonarkart
Department of Forensic Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
Peerayuht
P
Phuangphung
Department of Forensic Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
Sakda
S
Sathirareuangchai
Department of Pathology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
Mongkol
M
Uiprasertkul
Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand. prasert.aue@mahidol.ac.th.
Prasert
P
Auewarakul
D000220:Adaptation, Biological; D000328:Adult; D005260:Female; D006801:Humans; D009980:Influenza A virus / Q000235:genetics / Q000502:physiology; D008168:Lung / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009297:Nasal Mucosa / Q000502:physiology*; D020033:Protein Isoforms / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012641:Selection, Genetic; D014779:Virus Replication; D055815:Young Adult; D028901:alpha Karyopherins / Q000096:biosynthesis* / Q000235:genetics
D020033:Protein Isoforms; D012333:RNA, Messenger; D028901:alpha Karyopherins
Human lung cells; Human nasal mucosa; Human respiratory tract; Importin-α1 isoform; Importin-α3 isoform; Importin-α7 isoform; Influenza A virus; Interspecies barrier