Human Cytomegalovirus IE72 Protein Interacts with the Transcriptional Repressor hDaxx To Regulate LUNA Gene Expression during Lytic Infection

Reeves, Matthew B.; Woodhall, David L.; Compton, Teresa

doi:10.1128/jvi.02231-09

Cited by 33 publications

(42 citation statements)

References 65 publications

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“…These results suggest that a viral latency transcript is expressed at times during which IE gene expression is restricted. Further, this mimics the findings observed in natural and ex vivo HCMV latency models (40).…”

Section: Resultssupporting

confidence: 70%

A Myeloid Progenitor Cell Line Capable of Supporting Human Cytomegalovirus Latency and Reactivation, Resulting in Infectious Progeny

O’Connor

Murphy

2012

J Virol

115

159

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Human cytomegalovirus (HCMV) is a herpesvirus that establishes a lifelong, latent infection within a host. At times when the immune system is compromised, the virus undergoes a lytic reactivation producing infectious progeny. The identification and understanding of the biological mechanisms underlying HCMV latency and reactivation are not completely defined. To this end, we have developed a tractablein vitromodel system to investigate these phases of viral infection using a clonal population of myeloid progenitor cells (Kasumi-3 cells). Infection of these cells results in maintenance of the viral genome with restricted viral RNA expression that is reversed with the addition of the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA, also known as PMA). Additionally, a latent viral transcript (LUNA) is expressed at times where viral lytic transcription is suppressed. Infected Kasumi-3 cells initiate production of infectious virus following TPA treatment, which requires cell-to-cell contact for efficient transfer of virus to other cell types. Importantly, lytically infected fibroblast, endothelial, or epithelial cells can transfer virus to Kasumi-3 cells, which fail to initiate lytic replication until stimulated with TPA. Finally, inflammatory cytokines, in addition to the pharmacological agent TPA, are sufficient for transcription of immediate-early (IE) genes following latent infection. Taken together, our findings argue that the Kasumi-3 cell line is a tractablein vitromodel system with which to study HCMV latency and reactivation.

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Section: Resultssupporting

confidence: 70%

A Myeloid Progenitor Cell Line Capable of Supporting Human Cytomegalovirus Latency and Reactivation, Resulting in Infectious Progeny

O’Connor

Murphy

2012

J Virol

115

159

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“…Although an interaction between IE1 and hDaxx has been detected (62), and despite the dispersal of hDaxx in uninfected cells expressing IE1 (Fig. 4B), IE1 did not eliminate the recruitment of either hDaxx or ATRX to the HSV-1-induced foci (Fig.…”

Section: Discussionmentioning

confidence: 99%

The Replication Defect of ICP0-Null Mutant Herpes Simplex Virus 1 Can Be Largely Complemented by the Combined Activities of Human Cytomegalovirus Proteins IE1 and pp71

Everett

Bell

et al. 2013

J Virol

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Herpes simplex virus 1 (HSV-1) immediate-early protein ICP0 is required for efficient lytic infection and productive reactivation from latency and induces derepression of quiescent viral genomes. Despite being unrelated at the sequence level, ICP0 and human cytomegalovirus proteins IE1 and pp71 share some functional similarities in their abilities to counteract antiviral restriction mediated by components of cellular nuclear structures known as ND10. To investigate the extent to which IE1 and pp71 might substitute for ICP0, cell lines were developed that express either IE1 or pp71, or both together, in an inducible manner. We found that pp71 dissociated the hDaxx-ATRX complex and inhibited accumulation of these proteins at sites juxtaposed to HSV-1 genomes but had no effect on the promyelocytic leukemia protein (PML) or Sp100. IE1 caused loss of the small ubiquitinlike modifier (SUMO)-conjugated forms of PML and Sp100 and inhibited the recruitment of these proteins to HSV-1 genome foci but had little effect on hDaxx or ATRX in these assays. Both IE1 and pp71 stimulated ICP0-null mutant plaque formation, but neither to the extent achieved by ICP0. The combination of IE1 and pp71, however, inhibited recruitment of all ND10 proteins to viral genome foci, stimulated ICP0-null mutant HSV-1 plaque formation to near wild-type levels, and efficiently induced derepression of quiescent HSV-1 genomes. These results suggest that ND10-related intrinsic resistance results from the additive effects of several ND10 components and that the effects of IE1 and pp71 on subsets of these components combine to mirror the overall activities of ICP0.T he concept of intrinsic immunity, or intrinsic antiviral defense, has emerged in recent years as a means of cellular restriction of viral infections. First defined in retroviral systems (1), intrinsic resistance is mediated by constitutively expressed cellular proteins that in many cases are also involved in regulating cellular pathways. In contrast to acquired and innate immunity, intrinsic defense functions at the single-cell level and includes a wide diversity of mechanisms by which different viruses can be targeted at various stages of their replication cycles. Other defining characteristics of intrinsic resistance are (i) that it is often countered by viral regulatory proteins that target the relevant cellular repressors, (ii) that even in the absence of the viral countermeasures the restriction can be overcome by a high input of viral genomes, and (iii) that the efficiency of restriction varies between different cell types. Therefore, the defective phenotype of a mutant virus that does not express a relevant regulatory protein is often multiplicity and cell type dependent.In the case of herpesviruses, and in particular herpes simplex virus 1 (HSV-1) and human cytomegalovirus (HCMV), there is accumulating evidence that one aspect of intrinsic resistance is mediated by components of cellular nuclear substructures known as promyelocytic leukemia (PML) nuclear bodies (also known as ND10)...

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“…Daxx has previously been reported to bind to and/or transcriptionally repress cellular and viral promoters, including c-met, RelB target genes and CMV (Croxton et al, 2006;Morozov et al, 2008;Puto and Reed, 2008;Reeves et al, 2010;Zhang et al, 2010). It is not known whether ATRX is required for the Daxx-mediated repression of these genes, however, the Drosophila ATRX homolog was recently shown to repress the pannier gene through a promotermediated mechanism (Valadez-Graham et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

Single cell analysis of Daxx and ATRX-dependent transcriptional repression

Newhart¹,

Rafalska-Metcalf²,

Yang³

et al. 2012

Journal of Cell Science

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SummaryHistone H3.3 is a constitutively expressed H3 variant implicated in the epigenetic inheritance of chromatin structures. Recently, the PML-nuclear body (PML-NB)/Nuclear Domain 10 (ND10) proteins, Daxx and ATRX, were found to regulate replication-independent histone H3.3 chromatin assembly at telomeres and pericentric heterochromatin. As it is not completely understood how PML-NBs/ ND10s regulate transcription and resistance to viral infection, we have used a CMV-promoter-regulated inducible transgene array, at which Daxx and ATRX are enriched, to delineate the mechanisms through which they regulate transcription. When integrated into HeLa cells, which express both Daxx and ATRX, the array is refractory to activation. However, transcription can be induced when ICP0, the HSV-1 E3 ubiquitin ligase required to reverse latency, is expressed. As ATRX and Daxx are depleted from the activated array in ICP0-expressing HeLa cells, this suggests that they are required to maintain a repressed chromatin environment. As histone H3.3 is strongly recruited to the ICP0-activated array but does not co-localize with the DNA, this also suggests that chromatin assembly is blocked during activation. The conclusion that the Daxx and ATRX pathway is required for transcriptional repression and chromatin assembly at this site is further supported by the finding that an array integrated into the ATRX-negative U2OS cell line can be robustly activated and that histone H3.3 is similarly recruited and unincorporated into the chromatin. Therefore, this study has important implications for understanding gene silencing, viral latency and PML-NB/ND10 function.

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Human Cytomegalovirus IE72 Protein Interacts with the Transcriptional Repressor hDaxx To Regulate LUNA Gene Expression during Lytic Infection

Cited by 33 publications

References 65 publications

A Myeloid Progenitor Cell Line Capable of Supporting Human Cytomegalovirus Latency and Reactivation, Resulting in Infectious Progeny

A Myeloid Progenitor Cell Line Capable of Supporting Human Cytomegalovirus Latency and Reactivation, Resulting in Infectious Progeny

The Replication Defect of ICP0-Null Mutant Herpes Simplex Virus 1 Can Be Largely Complemented by the Combined Activities of Human Cytomegalovirus Proteins IE1 and pp71

Single cell analysis of Daxx and ATRX-dependent transcriptional repression

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