title: Human cytomegalovirus inactivates the G0/G1-APC/C ubiquitin ligase by Cdh1 dissociation.
abstract: The anaphase promoting complex/cyclosome (APC/C) is an E3 ubiquitin ligase that targets regulators of the cell division cycle for degradation by the 26S proteasome. Discovered as a key regulator of mitosis, the APC/C has more recently been recognized to also play a limiting role in the control of G(0) maintenance, G(1)/S-transition and DNA-replication. Human cytomegalovirus (HCMV) has been shown to interfere with cell cycle regulation at different levels. It can induce an S phase-prone proliferation program in quiescent cells but at the same time this virus directly inhibits competitive cellular DNA replication. Here we show, that human cytomegalovirus (HCMV) inactivates the G(0)/G(1) APC/C rapidly after infection of quiescent fibroblasts, resulting in the untimely stabilization of APC/C substrates. APC/C inactivation is caused by the dissociation of its positive regulator, Cdh1. Surprisingly, this dissociation is independent from known Cdh1 inhibitors, Emi1 and Cyclin A, suggesting that APC/C-Cdh1 inhibition by HCMV is directly caused by a viral protein or an intermediate cellular factor distinct from Emi1 and Cyclin A. Thus, upon infection of quiescent cells HCMV not only activates the E2F-dependent G(1)/S transcription program but also facilitates protein accumulation of APC/C substrates by rapid Cdh1 dissociation.
authors.affiliation: Department of Pediatrics, Laboratory for Molecular Biology, Charité, Humboldt University, Berlin, Germany.
authors.forename: Lüder
authors.initials: L
authors.lastname: Wiebusch
authors.forename: Miriam
authors.initials: M
authors.lastname: Bach
authors.forename: Ralf
authors.initials: R
authors.lastname: Uecker
authors.forename: Christian
authors.initials: C
authors.lastname: Hagemeier
mesh_terms: D064173:Anaphase-Promoting Complex-Cyclosome; D064199:Cdc20 Proteins; D064200:Cdh1 Proteins; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D003587:Cytomegalovirus / Q000502:physiology*; D004789:Enzyme Activation; D044783:F-Box Proteins; D016193:G1 Phase; D015967:Gene Expression Regulation, Viral; D006801:Humans; D011485:Protein Binding; D016192:Resting Phase, Cell Cycle; D013379:Substrate Specificity; D043743:Ubiquitin-Protein Ligase Complexes / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
chemical_list: D064199:Cdc20 Proteins; D064200:Cdh1 Proteins; D018797:Cell Cycle Proteins; D044783:F-Box Proteins; C498960:FBXO5 protein, human; C577584:FZR1 protein, human; C577488:CDC20 protein, human; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D044767:Ubiquitin-Protein Ligases