Expression of protein kinase A and protein kinase C during ongoing human cytomegalovirus infection.

During an HCMV infection, transcription of viral and cellular genes are mutually regulated. Several cellular proteins have been implicated in the regulation of the HCMV major immediate early promoter (MIEP) which have been shown to respond to cAMP as well as activation of protein kinase C (PKC). We have examined the effect of an ongoing HCMV infection at the mRNA level for the catalytic and regulatory subunits of protein kinase A (PKA) and alpha and beta isoforms of PKC. There was a moderate elevation for PKA C alpha and RI alpha at immediate early times (0.5-2 h) after HCMV infection. Later in the infection cycle (24-72 h), mRNA level for PKA regulatory subunit RI alpha and PKC alpha were decreased compared with control cells. Messenger RNA levels for the PKA RII alpha and RII beta as well as PKC beta were not affected by HCMV infection. During the infection cycle the PKA subunits and PKC isoforms appeared to be independently regulated. It was also evident that the basal mRNA levels of PKA subunits and the PKC isoforms were sufficient for the PKA and PKC activity required during an HCMV infection in permissive fibroblast cells.