NF-kappaB--a potential therapeutic target for inhibition of human cytomegalovirus (re)activation?
From clinical studies the proinflammatory cytokine TNFalpha was proposed to play a key role in human cytomegalovirus (HCMV) reactivation from latency. In vitro experiments confirmed that TNFalpha stimulates the activity of the HCMV IE1/2 enhancer/promoter, which controls immediate early protein IE1 and IE2 gene expression via activation of the transcription factor NF-kappaB and its binding to putative binding sites in the IE1/2 enhancer. NF-kappaB was also proposed to be involved in IE1-mediated autostimulation of this promoter. The IE1/2 enhancer of HCMV contains four putative NF-kappaB binding sites which differ in their distance to the transcription start site as well as in their sequence. Construction and testing of a series of promoter mutants demonstrated that NF-kappaB is essential for both TNFalpha and IE1 stimulation. Furthermore, we were able to show that although all four NF-kappaB sites bind NF-kappaB with similar affinity in vitro, the contribution to TNFalpha and IE1 stimulation differs in correlation with the distance to the transcription start site and the sequence. Site 1 and 3 play the most dominant role and site 2 an intermediate, while site 4, which is conserved in sequence but far distant from the transcription start site, had no influence on NF-kappaB-mediated regulation of the IE1/2 promoter. Specific inhibition of NF-kappaB signalling by co-expression of a dominant-negative IkappaB variant reduced TNFalpha stimulation of the IE1/2 enhancer/promoter by up to 80%. From this data, inhibitors of NF-kappaB activation are suggested to be an alternative therapeutical strategy to interfere with HCMV (re)activation in undifferentiated monocyte/granulocyte progenitor cells in patients with a high risk of inflammation-related HCMV (re)activation.
Prösch
Susanna
S
Institute of Virology, University Hospital Charité, Humboldt University, D-10098 Berlin, Germany.
Wuttke
Regine
R
Krüger
Detlev H
DH
Volk
Hans-Dieter
HD
D001483:Base Sequence; D001665:Binding Sites; D016384:Consensus Sequence; D003587:Cytomegalovirus / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D004742:Enhancer Elements, Genetic; D015967:Gene Expression Regulation, Viral / Q000276:immunology; D018922:HL-60 Cells; D006801:Humans; D020672:I-kappa B Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D017874:Immediate-Early Proteins / Q000502:physiology; D009000:Monocytes / Q000382:microbiology; D016297:Mutagenesis, Site-Directed; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000502:physiology; D010641:Phenotype; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000494:pharmacology / Q000502:physiology; D014764:Viral Proteins; D014775:Virus Activation / Q000502:physiology
D020672:I-kappa B Proteins; C088645:IE1 protein, cytomegalovirus; D017874:Immediate-Early Proteins; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D014764:Viral Proteins