Japanese Encephalitis Virus Infection Initiates Endoplasmic Reticulum Stress and an Unfolded Protein Response

AUTOR(ES)

Su, Hong-Lin

FONTE

American Society for Microbiology

RESUMO

The malfunctioning of the endoplasmic reticulum (ER) of cells in hosts ranging from yeast to mammals can trigger an unfolded protein response (UPR). Such malfunctioning can result from a variety of ER stresses, including the inhibition of protein glycosylation and calcium imbalance. To cope with ER stresses, cells may rely on the UPR to send a signal(s) from the ER to the nucleus to stimulate appropriate cellular responses, including induction of chaperone expression. During Japanese encephalitis virus (JEV) infection, the lumen of the ER rapidly accumulates substantial amounts of viral proteins for virus progeny production. In the present study, we demonstrate that as evidenced by certain chaperone inductions, JEV infection triggers the UPR in fibroblast BHK-21 cells and in neuronal N18 and NT-2 cells, in which JEV results in apoptotic cell death. By contrast, no UPR was observed in apoptosis-resistant K562 cells infected by JEV. JEV infection also activates expression of CHOP/GADD153, a distinctive transcription factor often induced by the UPR, and appears to trigger activation of p38 mitogen-activated protein kinase, a posttranslational activator of CHOP. Ectopic enforcement of CHOP expression enhanced JEV-induced apoptosis, whereas treatment with a p38-specific inhibitor, SB203580, partially blocked JEV-induced apoptosis. Interestingly, bcl-2 overexpression and treatment with a pancaspase inhibitor, z-VAD-fmk, inhibited CHOP induction and diminished JEV-induced apoptosis, suggesting that Bcl-2 and caspases could be the upstream regulators of CHOP. Our results thus suggest that virus-induced ER stress may participate, via p38-dependent and CHOP-mediated pathways, in the apoptotic process triggered by JEV infection.

Documentos Relacionados

• Membrane expansion alleviates endoplasmic reticulum stress independently of the unfolded protein response
• The unfolded protein response coordinates the production of endoplasmic reticulum protein and endoplasmic reticulum membrane.
• The Unfolded Protein Response Regulates Glutamate Receptor Export from the Endoplasmic ReticulumD⃞
• Protein quality control—linking the unfolded protein response to disease: Conference on ‘From Unfolded Proteins in the Endoplasmic Reticulum to Disease'
• Regulation of the dolichol pathway in human fibroblasts by the endoplasmic reticulum unfolded protein response