title: Attenuation of chemokine receptor function and surface expression as an immunomodulatory strategy employed by human cytomegalovirus is linked to vGPCR US28.
abstract: Some herpesviruses like human cytomegalovirus (HCMV) encode viral G protein-coupled receptors that cause reprogramming of cell signaling to facilitate dissemination of the virus, prevent immune surveillance and establish life-long latency. Human GPCRs are known to function in complex signaling networks involving direct physical interactions as well as indirect crosstalk of orthogonal signaling networks. The human chemokine receptor CXCR4 is expressed on hematopoietic stem cells, leukocytes, endothelial and epithelial cells, which are infected by HCMV or display reservoirs of latency.
  
  
  
  We investigated the potential heteromerization of US28 with CXCR4 as well as the influence of US28 on CXCR4 signaling. Using Bioluminescence Resonance Energy Transfer and luciferase-complementation based methods we show that US28 expression exhibits negative effects on CXCR4 signaling and constitutive surface expression in HEK293T cells. Furthermore, we demonstrate that this effect is not mediated by receptor heteromerization but via signaling crosstalk. Additionally, we show that in HCMV, strain TB40E, infected HUVEC the surface expression of CXCR4 is strongly downregulated, whereas in TB40E-delUS28 infected cells, CXCR4 surface expression is not altered in particular at late time points of infection.
  
  
  
  We show that the vGPCR US28 is leading to severely disturbed signaling and surface expression of the chemokine receptor CXCR4 thereby representing an effective mechanism used by vGPCRs to reprogram host cell signaling. In contrast to other studies, we demonstrate that these effects are not mediated via heteromerization.
authors.affiliation: Department of Chemistry and Pharmacy, Emil Fischer Center, University of Erlangen-Nuremberg, Erlangen, Germany.|Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors.forename: Theresa
authors.initials: T
authors.lastname: Frank
authors.affiliation: Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Reichel
authors.affiliation: Department of Neuroscience and Pharmacology, Laboratory for Molecular Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Olav
authors.initials: O
authors.lastname: Larsen
authors.affiliation: Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors.forename: Anne-Charlotte
authors.initials: AC
authors.lastname: Stilp
authors.affiliation: Department of Neuroscience and Pharmacology, Laboratory for Molecular Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Mette M
authors.initials: MM
authors.lastname: Rosenkilde
authors.affiliation: Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Stamminger
authors.affiliation: Department of Chemistry, School of Science, The University of Tokyo, Tokyo, Japan.
authors.forename: Takeaki
authors.initials: T
authors.lastname: Ozawa
authors.affiliation: Department of Chemistry and Pharmacy, Emil Fischer Center, University of Erlangen-Nuremberg, Erlangen, Germany. nuska.tschammer@nanotemper.de.|Present Address: NanoTemper Technologies GmbH, Floessergasse 4, 81069, Munich, Germany. nuska.tschammer@nanotemper.de.
authors.forename: Nuska
authors.identifier: 0000-0003-2433-3355
authors.initials: N
authors.lastname: Tschammer
mesh_terms: D003587:Cytomegalovirus / Q000276:immunology*; D003586:Cytomegalovirus Infections / Q000276:immunology* / Q000473:pathology / Q000821:virology; D019204:GTP-Binding Proteins / Q000276:immunology; D057809:HEK293 Cells; D006801:Humans; D056747:Immunomodulation; D019718:Receptors, CXCR4 / Q000276:immunology*; D019707:Receptors, Chemokine / Q000276:immunology*; D014764:Viral Proteins / Q000276:immunology*
chemical_list: C527276:CXCR4 protein, human; D019718:Receptors, CXCR4; D019707:Receptors, Chemokine; C411191:US28 receptor, Cytomegalovirus; D014764:Viral Proteins; D019204:GTP-Binding Proteins
keywords: Bioluminescence complementation; Bioluminescence resonance energy transfer; Chemokine receptor CXCR4; Constitutive activity; Signaling crosstalk; Viral G protein-coupled receptor US28