Activation of the apoptotic fas antigen-encoding gene upon influenza virus infection involving spontaneously produced beta-interferon

Abstract

We previously demonstrated that influenza virus infection induces apoptosis in culture cells. Here, we examined the activation of the Fas antigen gone that encodes an apoptosis mediating membrane protein in the virus infected cells. The virus elicited a transient but marked increase in Fas antigen mRNA 3 to 4 hr after infection, followed by the expression of the antigen on the cell surface Poly(I)-poly(C), a synthetic double-stranded RNA, similarly activated Fas antigen gene expression, and poly(I)-poly(C)-treated cells are highly susceptible to the cell killing effect of IgM isotype of anti-Fas monoclonal antibody. On the other hand, the IgG isotype of anti-Fas monoclonal antibody, which has an inhibitory effect on Fas Ag mediated cell death, suppressed the virus-induced cell death. Prior exposure of the cells to anti interferon-β antibody decreased the degree of cell death as well as the amount of Fas mRNA. The autophosphorylation activity of double-stranded RNA activated protein kinase was also decreased in the antibody-treated cells. Moreover, a protein kinase inhibitor, 2-aminopurine, blocked the Fas Ag gene activation by poly(I)-poly(C). These results suggested that the activation of Fas Ag gene in the early phase of infection is an important event for apoptosis, and that it is regulated by the double-stranded RNA/interferon system involving protein phosphorylation. © 1995 Academic Press, Inc.