CHOP and IRE1a-XBP1/JNK signaling promote Newcastle Disease Virus induced apoptosis and benefit virus proliferation

Yanrong Li; Ying Liao; Qiaona Niu; Feng Gu; Yingjie Sun; Chunchun Meng; Lei Tan; Cuiping Song; Xusheng Qiu; Chan Ding

The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/300129 doi: bioRxiv preprint In addition to mediating XBP1 mRNA splicing, IRE1α also recruits TRAF2 and 530 ASK1, subsequently activating MKK4/7 and JNK (68). JNK promotes apoptosis 531 either by directly regulating the apoptotic proteins activity or activating the 532 transcription factor for pro-apoptotic protein (69). We have shown that JNK was 533 phosphorylated at late stage of NDV infection (Fig. 3A) , and CHOP promotes this 534 activation (Fig. 3B, 3C) . We next asked whether IRE1α was involved in NDV-induced 535 JNK activation. HeLa cells were transfected with siIRE1α or sic before being infected 536 with NDV, and the phosphorylation level of JNK was examined by Western blotting. (Fig. 6D) . Accordingly, in SP600125 558 treated cells, NP mRNA was also greatly decreased, compared to that in 559 DMSO-treated cells (Fig. 6E) . Meanwhile, inhibition of JNK kinase activity reduced 560 the cleavage of PARP by 0.7-fold (Fig. 6D) . Moreover, the transcription of death 561 ligand TNF-α and cytokines IFN-β, IL-6, IL-8 was markedly suppressed in SP600125 562 treated cells, as evidenced by semi-quantitative real time RT-PCR (Fig. 6E) . To 563 validate above results, specifically knock down of JNK by siRNA was performed. As 564 shown in Fig. 6F , JNK was successfully depleted by siJNK (0.05-fold), which 565 significantly reduced the level of viral NP expression (0.3-fold), compared to that in 566 sic control cells. PARP cleavage was also greatly decreased by 0.3-fold (Fig. 6F ).