Synergistic induction of intercellular adhesion molecule-1 by the human cytomegalovirus transactivators IE2p86 and pp71 is mediated via an Sp1-binding site.
Human cytomegalovirus (HCMV) infection of transplant recipients is frequently associated with allograft vasculopathy and rejection. One potential mechanism is vascular injury from HCMV-triggered, immunologically mediated processes. HCMV infection has been shown to increase the expression of intercellular adhesion molecule-1 (ICAM-1). The objective of this study was to determine the molecular basis of HCMV-enhanced ICAM-1 gene expression. Transient transfection experiments identified the IE2p86 protein as a potent activator of the ICAM-1 promoter. The tegument protein pp71 showed a strong synergistic effect on IE2p86-mediated ICAM-1 promoter activation. Mutagenesis experiments defined a DNA element from -110 to -42 relative to the transcription start site as responsive for IE2p86. Further point mutations within this DNA element identified an Sp1-binding site that was essential for strong synergistic activation by IE2p86 and pp71. To confirm the activation of ICAM-1 gene expression, human fibroblasts (HFF) as well as endothelial cells (HUVEC) were infected with recombinant IE2p86- and pp71-expressing baculoviruses, respectively. In FACS analysis, a synergistic induction of ICAM-1 was detectable when cells were co-infected with the two recombinant baculoviruses. These findings clearly demonstrate that IE2p86 and pp71 are crucial regulatory factors for HCMV-induced ICAM-1 upregulation.
Kronschnabl
Martina
M
Institut für Klinische und Molekulare Virologie, Schlossgarten 4, 91054 Erlangen, Germany.
Stamminger
Thomas
T
Institut für Klinische und Molekulare Virologie, Schlossgarten 4, 91054 Erlangen, Germany.
D000818:Animals; D016367:Baculoviridae / Q000235:genetics; D001665:Binding Sites; D002478:Cells, Cultured; D003587:Cytomegalovirus / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D018411:Spodoptera / Q000821:virology; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D015533:Transcriptional Activation
C069186:IE2 protein, Cytomegalovirus; D017874:Immediate-Early Proteins; D016329:Sp1 Transcription Factor; D015534:Trans-Activators; D018799:Intercellular Adhesion Molecule-1