Regulation of cytomegalovirus gene expression: alpha and beta promoters are trans activated by viral functions in permissive human fibroblasts.
We have fused immediate (alpha) and delayed (beta) early promoter-regulatory sequences taken from the cytomegalovirus (CMV) genome to Escherichia coli lacZ (beta-galactosidase) as an indicator gene to study regulated expression of these promoters. After transfection of human fibroblast cells with plasmid constructs carrying beta-galactosidase fusions, and subsequent infection with CMV, we have demonstrated that viral trans-acting functions up-regulate the expression of these genes in a temporally authentic manner. The alpha promoter is activated even when de novo protein synthesis is blocked and when UV-inactivated virus is used, suggesting that, as for herpes simplex virus type 1 (HSV-1), a virion structural protein is responsible for its up-regulation. We have found that HSV-1, as well as CMV, is capable of trans activating the CMV alpha promoter. The beta promoter is activated by CMV but is completely unresponsive to HSV-1 infection. The temporal synthesis of the alpha and beta promoters in the transient expression system conforms with their natural regulation during viral replication. The beta-galactosidase fusions we describe provide a most exquisitely sensitive indicator system for the study of cis- and trans-acting viral regulatory functions.
Spaete
R R
RR
Mocarski
E S
ES
D002478:Cells, Cultured; D003587:Cytomegalovirus / Q000235:genetics*; D004274:DNA, Recombinant; D005786:Gene Expression Regulation; D005814:Genes, Viral; D006801:Humans; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D018139:Simplexvirus / Q000235:genetics; D013997:Time Factors; D014779:Virus Replication; D001616:beta-Galactosidase / Q000235:genetics
D004274:DNA, Recombinant; D001616:beta-Galactosidase