Binding of PKA-RII alpha to the adenovirus E1A(12S) oncoprotein correlateswith its nuclear translocation and an increase in PKA-dependent promoter activity

The adenovirus type 12 (Ad 12) E1A(12S) oncoprotein utilizes the cAMP/prote in kinase A (PKA) signal transduction pathway to activate expression of the viral E2 gene, the products of which are essential for viral replication. A central unsolved question is, however, whether E1A(12S) interacts directl y with PKA in the process of promoter activation. We show here that E1A(12S ) binds to the regulatory subunits (R) of PKA in vitro and in vivo. Interac tion depends on the N-terminus and the conserved region 1 (CR1) of EIA(12S) . Both domains are also essential for the activation of viral E2 gene expre ssion, infection of cells with Ad12 leads to the cellular redistribution of RII alpha from the cytoplasm into the nucleus. Furthermore, RII alpha is a lso located in the nucleus of cells transformed by El of Ad12 and transient expression of EIA,,, leads to the redistribution of RII alpha into the nuc leus in a N-terminus- and CR1-dependent manner. Cotransfection of E1A(12S) with RII alpha results in strong activation of the E2 promoter. Based on th ese results we conclude that E1A(12S) functions as a viral A-kinase anchori ng protein redistributing RII alpha from the cytoplasm into the nucleus whe re it is involved in E1A(12S)-mediated activation of the E2 promoter (C) 20 01 Academic Press.