The S phase of the cell cycle and its perturbation by human cytomegalovirus

Bain, Mark

doi:10.1002/rmv.551

Cited by 33 publications

(28 citation statements)

References 97 publications

(108 reference statements)

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“…In consequence, S/G 2 -specific activities that are not directly related to cyclin A2-CDK activity may contribute, at least temporarily, to the sustained repression of IE2 and UL37. This influence, however, should not be overestimated, given that also in HCMV-infected control cells, despite the inhibition of cellular DNA synthesis, a multitude of S/G 2 -specific activities and metabolic processes are likely to be induced by the actions of viral gene products (4,58).…”

Section: Discussionmentioning

confidence: 99%

Inhibition of Human Cytomegalovirus Immediate-Early Gene Expression by Cyclin A2-Dependent Kinase Activity

Oduro

Uecker

Hagemeier

et al. 2012

J Virol

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Human cytomegalovirus (HCMV) starts its lytic replication cycle only in the G 0 /G 1 phase of the cell division cycle. S/G 2 cells can be infected but block the onset of immediate-early (IE) gene expression. This block can be overcome by inhibition of cyclin-dependent kinases (CDKs), suggesting that cyclin A2, the only cyclin with an S/G 2 -specific activity profile, may act as a negative regulator of viral gene expression. To directly test this hypothesis, we generated derivatives of an HCMV-permissive glioblastoma cell line that express cyclin A2 in a constitutive, cell cycle-independent manner. We demonstrate that even moderate cyclin A2 overexpression in G 1 was sufficient to severely compromise the HCMV replicative cycle after high-multiplicity infection. This negative effect was composed of a strong but transient inhibition of IE gene transcription and a more sustained alteration of IE mRNA processing, resulting in reduced levels of UL37 and IE2, an essential transactivator of viral early gene expression. Consistently, cyclin A2-overexpressing cells showed a strong delay of viral early and late gene expression, as well as virus reproduction. All effects were dependent on CDK activity, as a cyclin A2 mutant deficient in CDK binding was unable to interfere with the HCMV infectious cycle. Interestingly, murine CMV, whose IE gene expression is known to be cell cycle independent, is not affected by cyclin A2. Instead, it upregulates cyclin A2-associated kinase activity upon infection. Understanding the mechanisms behind the HCMV-specific action of cyclin A2-CDK might reveal new targets for antiviral strategies.

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Section: Discussionmentioning

confidence: 99%

Inhibition of Human Cytomegalovirus Immediate-Early Gene Expression by Cyclin A2-Dependent Kinase Activity

Oduro

Uecker

Hagemeier

et al. 2012

J Virol

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“…HCMV infection induces cell cycle arrest, while simultaneously the virus sustains an active cellular metabolic state supporting productive infection (3). Infected cells arrest in a pseudo-G 1 state with high levels of cyclin E and cyclin E-associated kinase activity (4 -6).…”

Section: Human Cytomegalovirus (Hcmv)mentioning

confidence: 99%

Cyclin-dependent Kinases Phosphorylate the Cytomegalovirus RNA Export Protein pUL69 and Modulate Its Nuclear Localization and Activity

Rechter

Scott

Eickhoff

et al. 2009

Journal of Biological Chemistry

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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 strainspecific differences in the amount of CDK inhibitor-induced pUL69 aggregate formation. In all cases analyzed, the inhibitorinduced 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. Human cytomegalovirus (HCMV)2 is a member of the Herpesviridae family and a human pathogen with worldwide distribution. Primary HCMV infection of the immunocompetent host is usually asymptomatic, whereas severe disease can occur upon infection of the immunocompromised and immunonaive. HCMV is a leading cause of complications in transplant recipients and AIDS patients, and congenital infection may result in mental impairment and hearing loss (1).HCMV replication is differentially regulated in host cell types, and viral replication is dependent on regulation of the cell cycle (2). HCMV infection induces cell cycle arrest, while simultaneously the virus sustains an active cellular metabolic state supporting productive infection (3). Infected cells arrest in a pseudo-G 1 state with high levels of cyclin E and cyclin E-associated kinase activity (4 -6). A number of additional alterations of cyclin-dependent protein kinase (CDK) activity have also been described, such as increased synthesis and reduced degradation of cyclin B1, as well as cytoplasmic translocation of CDK1 in HCMV-infected cells (7). The up-regulation of CDK activity during HCMV replication implies that viral replication requires CDK activity to create an environment favorable for efficient viral transcription, genome replication, and assembly of viral particles. Several regulatory steps in HCMV replication are dependent on CDK activity, particularly those involving CDK1, -2, -7, and -9 (8 -12). Additionally, inhibition of CDK activity affects replication of HCMV and other herpesviruses (13). Roscovitine, a purine analog that preferentiall...

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“…CDK1-dependent phosphorylation of lamin A/C occurs at Ser 22 , Ser 392 , and probably farther sites (10,14,15). HCMV blocks the cell cycle through the action of viral regulatory proteins (16,17); however, it remains unclear whether HCMV is able to utilize the CDK1-based pathway for distortion of the nuclear lamina. A number of studies provided evidence that CMVs (including HCMV as well as murine CMV) and also other herpesviruses recruit another cellular lamin-phosphorylating kinase, namely protein kinase C (PKC).…”

mentioning

confidence: 99%

Novel Mode of Phosphorylation-triggered Reorganization of the Nuclear Lamina during Nuclear Egress of Human Cytomegalovirus

Milbradt

Webel

Auerochs

et al. 2010

Journal of Biological Chemistry

148

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The nucleocytoplasmic egress of viral capsids is a rate-limiting step in the replication of the human cytomegalovirus (HCMV). As reported recently, an HCMV-specific nuclear egress complex is composed of viral and cellular proteins, in particular protein kinases with the capacity to induce destabilization of the nuclear lamina. Viral protein kinase pUL97 and cellular protein kinase C (PKC) play important roles by phosphorylating several types of nuclear lamins. Using pUL97 mutants, we show that the lamin-phosphorylating activity of pUL97 is associated with a reorganization of nuclear lamin A/C. Either pUL97 or PKC has the potential to induce distinct punctate lamina-depleted areas at the periphery of the nuclear envelope, which were detectable in transiently transfected and HCMV-infected cells. Using recombinant HCMV, which produces green fluorescent protein-labeled viral capsids, the direct transition of viral capsids through these areas could be visualized. This process was sensitive to an inhibitor of pUL97/PKC activity. The pUL97-mediated phosphorylation of lamin A/C at Ser 22 generated a novel binding motif for the peptidyl-prolyl cis/trans-isomerase Pin1. In HCMV-infected fibroblasts, the physiological localization of Pin1 was altered, leading to recruitment of Pin1 to viral replication centers and to the nuclear lamina. The local increase in Pin1 peptidyl-prolyl cis/trans-isomerase activity may promote conformational modulation of lamins. Thus, we postulate a novel phosphorylation-triggered mechanism for the reorganization of the nuclear lamina in HCMVinfected cells. Human cytomegalovirus (HCMV)2 belongs to the ␤-herpesvirus subfamily, exhibiting worldwide distribution. When infecting immunocompetent individuals, HCMV possesses low pathogenicity, causing mainly asymptomatic infections. In immunocompromised or immunosuppressed hosts, HCMV infection can cause severe and even life-threatening diseases, including pneumonitis, retinitis, hepatitis, encephalitis, and gastroenteritis (1-3).HCMV replication is based on a nuclear phase, a characteristic of most DNA viruses. Transition from the nuclear to the cytoplasmic phase is determined by the nuclear exit of DNAfilled capsids budding through the inner nuclear membrane (INM) (4 -6). The site-specific budding of viral capsids through distinct locally occurring invaginations in the INM of HCMVinfected cells was clearly illustrated by Buser et al. (7) using electron microscopic analysis. The proteinaceous network of the nuclear lamina, underlying the INM, constitutes a major obstacle for the nuclear egress of capsids. Lamins, belonging to type V intermediate filament proteins, are the main constituents of the nuclear lamina and are grouped into A and B types. A-type lamins (A, C, A⌬10, and C2; collectively lamin A/C) result from alternative splicing of the LMNA gene. B-type lamins are encoded by the LMNB1 (B1) or LMNB2 (B2, B3) gene (8, 9). A major function of the nuclear lamina is to maintain the structure of the nuclear envelope. During mitosis, the nuclear lamin...

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The S phase of the cell cycle and its perturbation by human cytomegalovirus

Cited by 33 publications

References 97 publications

Inhibition of Human Cytomegalovirus Immediate-Early Gene Expression by Cyclin A2-Dependent Kinase Activity

Inhibition of Human Cytomegalovirus Immediate-Early Gene Expression by Cyclin A2-Dependent Kinase Activity

Cyclin-dependent Kinases Phosphorylate the Cytomegalovirus RNA Export Protein pUL69 and Modulate Its Nuclear Localization and Activity

Novel Mode of Phosphorylation-triggered Reorganization of the Nuclear Lamina during Nuclear Egress of Human Cytomegalovirus

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