title: Modulation of human cytomegalovirus immediate-early gene enhancer by mitogen-activated protein kinase kinase kinase-1.
abstract: The immediate-early (IE) promoter of human cytomegalovirus (HCMV) constitutes a primary genetic switch, which determines the progression of viral infection. Earlier reports by others have shown mitogen-activated protein kinase kinase kinase-1 (MEKK1) to be able to up-regulate HCMV-IE promoter through downstream mitogen-activated protein kinase (MAPK) pathways. However, we noticed that the activation of the HCMV-IE promoter by constitutively active MEKK1 (MEKK1-TRU) might not be through the MAPK pathways. Using a HCMV-IE enhancer/promoter (- 522 to + 72) driving a luciferase reporter, we demonstrated that the downstream MAPK activation actually repressed the up-regulation of the promoter by MEKK1 in CHO-K1 and human 293 cells. We further found that the up-regulation of HCMV-IE promoter by MEKK1 could be in great extent suppressed by over-expression of IkappaBalpha. Deletion of the NFkappaB/rel sites in the HCMV-IE enhancer region by mutagenesis proportionally reduced the transcriptional activation by MEKK1-TRU, whereas deletion of the ATF/CREB binding sites or cyclic AMP response elements (CRE) had no effects. Furthermore, the NFkappaB/rel deletion mutant also showed repression on the basic transcription activity of the HCMV-IE promoter. Our results indicate that the NFkappaB/rel sites are not only responsible for the modulation of HCMV-IE enhancer activity by MEKK1 but also control the basic transcription activity of the HCMV-IE promoter. On the other hand, the four consensus CRE sites were found to have no function in the activation of the promoter by MEKK1.
authors.affiliation: Chiron Corporation, 4560 Horton Street, Emeryville, California 94608-2916, USA.
authors.forename: B
authors.initials: B
authors.lastname: Sun
authors.forename: G
authors.initials: G
authors.lastname: Harrowe
authors.forename: C
authors.initials: C
authors.lastname: Reinhard
authors.forename: C
authors.initials: C
authors.lastname: Yoshihara
authors.forename: K
authors.initials: K
authors.lastname: Chu
authors.forename: S
authors.initials: S
authors.lastname: Zhuo
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000235:genetics; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism; D003587:Cytomegalovirus / Q000235:genetics*; D004742:Enhancer Elements, Genetic; D017353:Gene Deletion; D017781:Genes, Immediate-Early; D005822:Genetic Vectors / Q000494:pharmacology; D006801:Humans; D051550:I-kappa B Kinase; D017874:Immediate-Early Proteins; D007527:Isoenzymes / Q000096:biosynthesis; D048031:JNK Mitogen-Activated Protein Kinases; D048728:MAP Kinase Kinase Kinase 1; D008562:Membrane Glycoproteins; D020928:Mitogen-Activated Protein Kinases / Q000096:biosynthesis / Q000502:physiology; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D051381:Rats; D012097:Repressor Proteins / Q000502:physiology; D015534:Trans-Activators; D015533:Transcriptional Activation; D015854:Up-Regulation / Q000235:genetics; D014759:Viral Envelope Proteins; D014764:Viral Proteins; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; C088645:IE1 protein, cytomegalovirus; C069186:IE2 protein, Cytomegalovirus; D017874:Immediate-Early Proteins; D007527:Isoenzymes; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D012097:Repressor Proteins; D015534:Trans-Activators; C077406:UL115 protein, Human herpesvirus 5; D014759:Viral Envelope Proteins; D014764:Viral Proteins; C071440:glycoprotein H, Cytomegalovirus; C499358:glycoprotein H, Human cytomegalovirus; C439068:glycoprotein O, cytomegalovirus; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048728:MAP Kinase Kinase Kinase 1; C482576:MAP3K1 protein, human