Role of the human cytomegalovirus major immediate-early promoter's 19-base-pair-repeat cyclic AMP-response element in acutely infected cells.
Prior studies have suggested a role of the five copies of the 19-bp-repeat cyclic AMP (cAMP)-response element (CRE) in major immediate-early (MIE) promoter activation, the rate-limiting step in human cytomegalovirus (HCMV) replication. We used two different HCMV genome modification strategies to test this hypothesis in acutely infected cells. We report the following: (i) the CREs do not govern basal levels of MIE promoter activity at a high or low multiplicity of infection (MOI) in human foreskin fibroblast (HFF)- or NTera2-derived neuronal cells; (ii) serum and virion components markedly increase MIE promoter-dependent transcription at a low multiplicity of infection (MOI), but this increase is not mediated by the CREs; (iii) forskolin stimulation of the cAMP signaling pathway induces a two- to threefold increase in MIE RNA levels in a CRE-specific manner at a low MOI in both HFF- and NTera2-derived neuronal cells; and (iv) the CREs do not regulate basal levels of HCMV DNA replication at a high or low MOI in HFF. Their presence does impart a forskolin-induced increase in viral DNA replication at a low MOI but only when basal levels of MIE promoter activity are experimentally diminished. In conclusion, the 19-bp-repeat CREs add to the robust MIE promoter activity that occurs in the acutely infected stimulated cells, although the CREs' greater role may be in other settings.
Keller
M J
MJ
Department of Internal Medicine and the Helen C. Levitt Center for Viral Pathogenesis and Disease, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, USA.
Wheeler
D G
DG
Cooper
E
E
Meier
J L
JL
D020029:Base Pairing; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism*; D003587:Cytomegalovirus / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D003586:Cytomegalovirus Infections / Q000821:virology; D015967:Gene Expression Regulation, Viral; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics*; D009154:Mutation; D011401:Promoter Regions, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D020218:Response Elements / Q000235:genetics*; D014158:Transcription, Genetic; D014775:Virus Activation; D014779:Virus Replication
D017874:Immediate-Early Proteins; D000242:Cyclic AMP