Interferon antagonist function of Japanese encephalitis virus NS4A and its interaction with DEAD-box RNA helicase DDX42.
The interferon (IFN) antagonists of Japanese encephalitis virus (JEV) proteins contribute to the JE pathogenesis. Most flavivirus non-structural (NS) proteins correlate with virus-induced inflammation and immune escape. NS4A proteins of West Nile virus and dengue type 2 virus have been demonstrated to inhibit IFN signaling. In this study, JEV NS4A without the C-terminal 2K domain has been demonstrated to partially block activation of an IFN-stimulated response element (ISRE)-based cis-reporter by IFN-alpha/beta. In addition, JEV NS4A significantly inhibited the phosphorylation levels of STAT1 and STAT2, but not TYK2 in the IFN-treated cells. Moreover, the N-terminus of a RNA helicase DDX42 protein identified using a phage display human brain cDNA library have been demonstrated to specifically bind to JEV NS4A in vitro using a co-immunoprecipitation assay. The interaction between JEV NS4A and RNA helicase DDX42 showed partial co-localization in human medulloblastoma TE-671 cells by confocal microscopy. Importantly, the expression of N-terminal DDX42 is able to overcome JEV-induced antagonism of IFN responses. Therefore, these results show that JEV NS4A without the C-terminal 2K domain is associated with modulation of the IFN response and the interaction of JEV NS4A with RNA helicase DDX42 could be important for JE pathogenesis.
Lin
Cheng-Wen
CW
Department of Medical Laboratory Science and Biotechnology, China Medical University, Taichung, Taiwan. cwlin@mail.cmu.edu.tw
Cheng
Chieh-Wen
CW
Yang
Tsuey-Ching
TC
Li
Shih-Wein
SW
Cheng
Mei-Hsiu
MH
Wan
Lei
L
Lin
Ying-Ju
YJ
Lai
Chih-Ho
CH
Lin
Wei-Yong
WY
Kao
Ming-Ching
MC
D000818:Animals; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D006224:Cricetinae; D053487:DEAD-box RNA Helicases / Q000378:metabolism*; D004664:Encephalitis Virus, Japanese / Q000235:genetics / Q000378:metabolism*; D004672:Encephalitis, Japanese / Q000821:virology*; D015967:Gene Expression Regulation, Viral; D015723:Gene Library; D049452:Green Fluorescent Proteins / Q000235:genetics; D006801:Humans; D007370:Interferon Type I / Q000037:antagonists & inhibitors* / Q000378:metabolism; D053612:Janus Kinases / Q000378:metabolism; D008164:Luminescent Proteins / Q000235:genetics; D018613:Microscopy, Confocal; D010766:Phosphorylation; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017413:Ribonucleoprotein, U2 Small Nuclear / Q000378:metabolism*; D050791:STAT Transcription Factors / Q000378:metabolism; D015398:Signal Transduction; D014709:Vero Cells; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D000097573:Red Fluorescent Protein
D053487:DEAD-box RNA Helicases; D049452:Green Fluorescent Proteins; D007370:Interferon Type I; D053612:Janus Kinases; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D017413:Ribonucleoprotein, U2 Small Nuclear; D050791:STAT Transcription Factors; D014764:Viral Proteins; D000097573:Red Fluorescent Protein; C408625:DDX42 protein, human