MAPK signaling contributes to rotaviral-induced cholangiocyte injury and viral replication.

BACKGROUND: Biliary atresia is a disease of newborns that results in obliteration of the biliary tree. Infection of mice with rhesus rotavirus (RRV) results in a cholangiopathy mirroring human disease. The Mitogen Associated Protein Kinase (MAPK) signaling pathway can be activated by viral binding to cell-surface receptors. We hypothesized that RRV infection of cholangiocytes results in activation of MAPK signaling.
METHODS: Extrahepatic bile ducts from BALB/c pups or immortalized cholangiocytes subjected to RRV infection or control were analyzed, using Western blots, for phosphorylated members of the MAPK family: p38, ERK 1/2, JNK 1/2, and downstream transcription factors. Inhibitors of the MAPK were used to downregulate activity. Viral replication and cytolysis in cholangiocytes were evaluated post-MAPK inhibition.
RESULTS: Phosphorylation of all MAPK increased in RRV-infected mice and cholangiocytes. Several downstream transcription factors had increased activity in vitro. Inhibition of p38 and ERK 1/2 resulted in decreased viral replication. ERK 1/2 inhibition decreased cytolysis without affecting viral entry or binding.
CONCLUSIONS: RRV infection of cholangiocytes resulted in increased MAPK signaling. Inhibition of p38 and ERK 1/2 influenced the ability of rotavirus to replicate. These novel findings provide insight into the signaling cascade involved in RRV-induced cholangiocyte injury.