Adenovirus infection inactivates the translational inhibitors 4E-BP1 and 4E-BP2

Abstract

Infection with many viruses results in the selective shutoff of host protein synthesis. A common target for virus interference with host protein synthesis is the cap-binding protein complex, eIF4F. The large subunit of the complex, eIF4G, is cleaved upon picornavirus (except cardiovirus) infection. Infection with adenovirus and influenza virus causes dephosphorylation of the cap-binding subunit, eIF4E. Recently, it has been shown that infection with poliovirus or encephalomyocarditis virus activates 4E-BP1, which is a specific inhibitor of eIF4E. Here we show that early in adenovirus infection, 4E-BP1 and its related protein 4E-BP2 are phosphorylated and hence inactivated. This is not consistent with a role of 4E-BPs in adenovirus-induced shutoff, but could explain the increase in protein synthesis reported early in infection. Phosphorylation of 4E-BP1 and 4E-BP2 is consistent with earlier findings in adenovirus-infected cells on the activation of the protein kinase p70(S6k) whose phosphorylation lies on the same pathway as 4E-BPs, by E1A. Findings similar to those described here were reported for 4E-BP1 by D. Feigenblum and R. J. Schneider (1996, Mol. Cell. Biol. 16, 5450-5457).