Avian reovirus sigma A and sigma NS proteins activate the phosphatidylinositol 3-kinase-dependent Akt signalling pathway

摘要

The present study was conducted to identify avian reovirus (ARV) proteins that can activate the phosphatidylinositol 3-kinase (PI3K)-dependent Akt pathway. Based on ARV protein amino acid sequence analysis, sigma A, sigma NS, mu A, mu B and mu NS were identified as putative proteins capable of mediating PI3K/Akt pathway activation. The recombinant plasmids sigma A-pcAGEN, sigma NS-pcAGEN, mu A-pcAGEN, mu B-pcAGEN and mu NS-pcAGEN were constructed and used to transfect Vero cells, and the expression levels of the corresponding genes were quantified by immunofluorescence and Western blot analysis. Phosphorylated Akt (P-Akt) levels in the transfected cells were measured by flow cytometry and Western blot analysis. The results showed that the sigma A, sigma NS, mu A, mu B and mu NS genes were expressed in Vero cells. sigma A-expressing and sigma NS-expressing cells had higher P-Akt levels than negative control cells, pcAGEN-expressing cells and cells designed to express other proteins (i.e., mu A, mu B and mu NS). Pre-treatment with the PI3K inhibitor LY294002 inhibited Akt phosphorylation in sigma A- and sigma NS-expressing cells. These results indicate that the sigma A and sigma NS proteins can activate the PI3K/Akt pathway.