title: Distinct Roles for Human Cytomegalovirus Immediate Early Proteins IE1 and IE2 in the Transcriptional Regulation of MICA and PVR/CD155 Expression.
abstract: Elimination of virus-infected cells by cytotoxic lymphocytes is triggered by activating receptors, among which NKG2D and DNAM-1/CD226 play an important role. Their ligands, that is, MHC class I-related chain (MIC) A/B and UL16-binding proteins (ULBP)1-6 (NKG2D ligand), Nectin-2/CD112, and poliovirus receptor (PVR)/CD155 (DNAM-1 ligand), are often induced on virus-infected cells, although some viruses, including human CMV (HCMV), can block their expression. In this study, we report that infection of different cell types with laboratory or low-passage HCMV strains upregulated MICA, ULBP3, and PVR, with NKG2D and DNAM-1 playing a role in NK cell-mediated lysis of infected cells. Inhibition of viral DNA replication with phosphonoformic acid did not prevent ligand upregulation, thus indicating that early phases of HCMV infection are involved in ligand increase. Indeed, the major immediate early (IE) proteins IE1 and IE2 stimulated the expression of MICA and PVR, but not ULBP3. IE2 directly activated MICA promoter via its binding to an IE2-responsive element that we identified within the promoter and that is conserved among different alleles of MICA. Both IE proteins were instead required for PVR upregulation via a mechanism independent of IE DNA binding activity. Finally, inhibiting IE protein expression during HCMV infection confirmed their involvement in ligand increase. We also investigated the contribution of the DNA damage response, a pathway activated by HCMV and implicated in ligand regulation. However, silencing of ataxia telangiectasia mutated, ataxia telangiectasia and Rad3-related protein, and DNA-dependent protein kinase did not influence ligand expression. Overall, these data reveal that MICA and PVR are directly regulated by HCMV IE proteins, and this may be crucial for the onset of an early host antiviral response.
authors.affiliation: Department of Molecular Medicine, Pasteur Institute-Cenci Bolognetti Foundation, Sapienza University of Rome, 00162 Rome, Italy.
authors.forename: Benedetta
authors.identifier: 0000-0002-4296-8947
authors.initials: B
authors.lastname: Pignoloni
authors.affiliation: Department of Molecular Medicine, Pasteur Institute-Cenci Bolognetti Foundation, Sapienza University of Rome, 00162 Rome, Italy.
authors.forename: Cinzia
authors.identifier: 0000-0003-0636-7607
authors.initials: C
authors.lastname: Fionda
authors.affiliation: Department of Public Health and Pediatric Sciences, University of Turin, 10126 Turin, Italy.
authors.forename: Valentina
authors.identifier: 0000-0002-9336-7906
authors.initials: V
authors.lastname: Dell'Oste
authors.affiliation: Department of Life Sciences and Systems Biology, University of Turin, 10123 Turin, Italy; and.
authors.forename: Anna
authors.identifier: 0000-0003-4256-5774
authors.initials: A
authors.lastname: Luganini
authors.affiliation: Department of Molecular Medicine, Pasteur Institute-Cenci Bolognetti Foundation, Sapienza University of Rome, 00162 Rome, Italy.
authors.forename: Marco
authors.identifier: 0000-0002-9620-538X
authors.initials: M
authors.lastname: Cippitelli
authors.affiliation: Department of Molecular Medicine, Pasteur Institute-Cenci Bolognetti Foundation, Sapienza University of Rome, 00162 Rome, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Zingoni
authors.affiliation: Department of Public Health and Pediatric Sciences, University of Turin, 10126 Turin, Italy.
authors.forename: Santo
authors.identifier: 0000-0002-3153-2865
authors.initials: S
authors.lastname: Landolfo
authors.affiliation: Department of Life Sciences and Systems Biology, University of Turin, 10123 Turin, Italy; and.
authors.forename: Giorgio
authors.identifier: 0000-0002-1583-9146
authors.initials: G
authors.lastname: Gribaudo
authors.affiliation: Department of Molecular Medicine, Pasteur Institute-Cenci Bolognetti Foundation, Sapienza University of Rome, 00162 Rome, Italy; angela.santoni@uniroma1.it cristina.cerboni@uniroma1.it.|Mediterranean Neurological Institute-Neuromed, 86077 Pozzilli (Isernia), Italy.
authors.forename: Angela
authors.identifier: 0000-0003-1206-7731
authors.initials: A
authors.lastname: Santoni
authors.affiliation: Department of Molecular Medicine, Pasteur Institute-Cenci Bolognetti Foundation, Sapienza University of Rome, 00162 Rome, Italy; angela.santoni@uniroma1.it cristina.cerboni@uniroma1.it.
authors.forename: Cristina
authors.identifier: 0000-0002-0371-9534
authors.initials: C
authors.lastname: Cerboni
mesh_terms: D000945:Antigens, Differentiation, T-Lymphocyte / Q000235:genetics; D002460:Cell Line; D003602:Cytotoxicity, Immunologic; D004261:DNA Replication / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects / Q000821:virology; D017245:Foscarnet / Q000494:pharmacology; D058851:GPI-Linked Proteins / Q000235:genetics; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D054884:Host-Pathogen Interactions; D006801:Humans; D017874:Immediate-Early Proteins / Q000378:metabolism* / Q000494:pharmacology; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics; D007694:Killer Cells, Natural / Q000276:immunology; D055655:NK Cell Lectin-Like Receptor Subfamily K / Q000235:genetics; D011991:Receptors, Virus / Q000235:genetics*; D015534:Trans-Activators / Q000378:metabolism* / Q000494:pharmacology; D015533:Transcriptional Activation; D015854:Up-Regulation; D014764:Viral Proteins / Q000235:genetics; D014779:Virus Replication / Q000187:drug effects; D000098862:T Lineage-Specific Activation Antigen 1
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D000098862:T Lineage-Specific Activation Antigen 1; D058851:GPI-Linked Proteins; D015395:Histocompatibility Antigens Class I; C088645:IE1 protein, cytomegalovirus; C069186:IE2 protein, Cytomegalovirus; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; C527085:KLRK1 protein, human; C099187:MHC class I-related chain A; D055655:NK Cell Lectin-Like Receptor Subfamily K; D011991:Receptors, Virus; D015534:Trans-Activators; C423229:ULBP3 protein, human; D014764:Viral Proteins; C066100:poliovirus receptor; D017245:Foscarnet