title: Platelet-derived growth factor-alpha receptor activation is required for human cytomegalovirus infection.
abstract: Human cytomegalovirus (HCMV) is a ubiquitous human herpesvirus that can cause life-threatening disease in the fetus and the immunocompromised host. Upon attachment to the cell, the virus induces robust inflammatory, interferon- and growth-factor-like signalling. The mechanisms facilitating viral entry and gene expression are not clearly understood. Here we show that platelet-derived growth factor-alpha receptor (PDGFR-alpha) is specifically phosphorylated by both laboratory and clinical isolates of HCMV in various human cell types, resulting in activation of the phosphoinositide-3-kinase (PI(3)K) signalling pathway. Upon stimulation by HCMV, tyrosine-phosphorylated PDGFR-alpha associated with the p85 regulatory subunit of PI(3)K and induced protein kinase B (also known as Akt) phosphorylation, similar to the genuine ligand, PDGF-AA. Cells in which PDGFR-alpha was genetically deleted or functionally blocked were non-permissive to HCMV entry, viral gene expression or infectious virus production. Re-introducing human PDGFRA gene into knockout cells restored susceptibility to viral entry and essential viral gene expression. Blockade of receptor function with a humanized PDGFR-alpha blocking antibody (IMC-3G3) or targeted inhibition of its kinase activity with a small molecule (Gleevec) completely inhibited HCMV viral internalization and gene expression in human epithelial, endothelial and fibroblast cells. Viral entry in cells harbouring endogenous PDGFR-alpha was competitively inhibited by pretreatment with PDGF-AA. We further demonstrate that HCMV glycoprotein B directly interacts with PDGFR-alpha, resulting in receptor tyrosine phosphorylation, and that glycoprotein B neutralizing antibodies inhibit HCMV-induced PDGFR-alpha phosphorylation. Taken together, these data indicate that PDGFR-alpha is a critical receptor required for HCMV infection, and thus a target for novel anti-viral therapies.
authors.affiliation: Department of Neurosciences, California Pacific Medical Center Research Institute, Suite 220, 475 Brannan Street, San Francisco, California 94107, USA.
authors.forename: Liliana
authors.initials: L
authors.lastname: Soroceanu
authors.forename: Armin
authors.initials: A
authors.lastname: Akhavan
authors.forename: Charles S
authors.initials: CS
authors.lastname: Cobbs
mesh_terms: D000818:Animals; D002460:Cell Line; D003587:Cytomegalovirus / Q000502:physiology*; D003586:Cytomegalovirus Infections / Q000378:metabolism* / Q000821:virology*; D004789:Enzyme Activation / Q000187:drug effects; D015967:Gene Expression Regulation, Viral; D006801:Humans; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000378:metabolism / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014759:Viral Envelope Proteins / Q000378:metabolism; D053586:Virus Internalization
chemical_list: D010982:Platelet-Derived Growth Factor; D014759:Viral Envelope Proteins; C040495:glycoprotein B, Simplexvirus; C075278:platelet-derived growth factor A; D019000:Phosphotyrosine; D019869:Phosphatidylinositol 3-Kinases; D020796:Receptor, Platelet-Derived Growth Factor alpha; D051057:Proto-Oncogene Proteins c-akt