title: Cyclin-dependent Kinases Phosphorylate the Cytomegalovirus RNA Export Protein pUL69 and Modulate Its Nuclear Localization and Activity.
abstract: Replication of human cytomegalovirus (HCMV) is subject to regulation by cellular protein kinases. Recently, we and others reported that inhibition of cyclin-dependent protein kinases (CDKs) or the viral CDK ortholog pUL97 can induce intranuclear speckled aggregation of the viral mRNA export factor, pUL69. Here we provide the first evidence for a direct regulatory role of CDKs on pUL69 functionality. Although replication of all HCMV strains was dependent on CDK activity, we found strain-specific differences in the amount of CDK inhibitor-induced pUL69 aggregate formation. In all cases analyzed, the inhibitor-induced pUL69 aggregates were clearly localized within viral replication centers but not subnuclear splicing, pore complex, or aggresome structures. The CDK9 and cyclin T1 proteins colocalized with these pUL69 aggregates, whereas other CDKs behaved differently. Phosphorylation analyses in vivo and in vitro demonstrated pUL69 was strongly phosphorylated in HCMV-infected fibroblasts and that CDKs represent a novel class of pUL69-phosphorylating kinases. Moreover, the analysis of CDK inhibitors in a pUL69-dependent nuclear mRNA export assay provided evidence for functional impairment of pUL69 under suppression of CDK activity. Thus, our data underline the crucial importance of CDKs for HCMV replication, and indicate a direct impact of CDK9-cyclin T1 on the nuclear localization and activity of the viral regulator pUL69.
authors.affiliation: Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, Erlangen 91054, Germany, GPC Biotech AG, 82152 Martinsried, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Rechter
authors.forename: Gillian M
authors.initials: GM
authors.lastname: Scott
authors.forename: Jan
authors.initials: J
authors.lastname: Eickhoff
authors.forename: Katrin
authors.initials: K
authors.lastname: Zielke
authors.forename: Sabrina
authors.initials: S
authors.lastname: Auerochs
authors.forename: Regina
authors.initials: R
authors.lastname: Müller
authors.forename: Thomas
authors.initials: T
authors.lastname: Stamminger
authors.forename: William D
authors.initials: WD
authors.lastname: Rawlinson
authors.forename: Manfred
authors.initials: M
authors.lastname: Marschall
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism* / Q000821:virology; D056906:Cyclin T; D042863:Cyclin-Dependent Kinase 9 / Q000378:metabolism*; D016213:Cyclins / Q000378:metabolism*; D003587:Cytomegalovirus / Q000502:physiology*; D003586:Cytomegalovirus Infections / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism* / Q000821:virology; D006367:HeLa Cells; D006801:Humans; D010766:Phosphorylation; D012333:RNA, Messenger / Q000378:metabolism; D012367:RNA, Viral / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism*; D014779:Virus Replication / Q000502:physiology
chemical_list: C503684:CCNT1 protein, human; D056906:Cyclin T; D016213:Cyclins; D012333:RNA, Messenger; D012367:RNA, Viral; D015534:Trans-Activators; C446019:pUL69 protein, Human herpesvirus 5; C467969:CDK9 protein, human; D042863:Cyclin-Dependent Kinase 9