📄 The endoplasmic reticulum stress sensor IRE1α protects cells from apoptosis induced by the coronavirus infectious bronchitis virus

© 2014, American Society for Microbiology. The unfolded-protein response (UPR) is a signal transduction cascade triggered by perturbation of the homeostasis of the endoplasmic reticulum (ER). UPR resolves ER stress by activating a cascade of cellular responses, including the induction of molecular chaperones, translational attenuation, ER-associated degradation, and other mechanisms. Under prolonged and irremediable ER stress, however, the UPR can also trigger apoptosis. Here, we report that in cells infected with the avian coronavirus infectious bronchitis virus (IBV), ER stress was induced and the IRE1α-XBP1 pathway of UPR was activated. Knockdown and overexpression experiments demonstrated that IRE1α protects infected cells from IBV-induced apoptosis, which required both its kinase and RNase activities. Our data also suggest that splicing of XBP1 mRNA by IRE1α appears to convert XBP1 from a proapoptotic XBP1u protein to a prosurvival XBP1s protein. Moreover, IRE1α antagonized IBV-induced apoptosis by modulating the phosphorylation status of the proapoptotic c-Jun N-terminal kinase (JNK) and the prosurvival RAC-alpha serine/threonine- protein kinase (Akt). Taken together, the data indicate that the ER stress sensor IRE1α is activated in IBV-infected cells and serves as a survival factor during coronavirus infection.

keywords 🔗 bronchitis virus (233) 🔗 endoplasmic reticulum (78) 🔗 coronavirus infection (270) 🔗 infected cells (307) 🔗 infectious bronchitis (235)

download 🔖 [BibTeX]