Cellular defense against latent colonization foiled by human cytomegalovirus UL138 protein

Lee, Song Hee; Albright, Emily R.; Lee, Jeong-Hee; Jacobs, Derek; Kalejta, Robert F.

doi:10.1126/sciadv.1501164

Cited by 57 publications

(91 citation statements)

References 88 publications

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“…1E). As previously reported (53,54,68), treatment with the histone deacetylase (HDAC) inhibitor VPA prevented silencing of IE1 gene expression during infection with AD169 in parental THP-1 cells as well as in eH3.1-and eH3.3-expressing THP-1 cells (Fig. 1E).…”

Section: Resultssupporting

confidence: 54%

“…Chromatin immunoprecipitation (ChIP) assays were performed as previously described (54). Briefly, infected cells were collected, washed once with PBS, and fixed with 1% formaldehyde for 8 min at room temperature, followed by addition of glycine to 125 mM to quench the reaction.…”

Section: Cells and Infectionsmentioning

confidence: 99%

“…Equal amounts of total DNA were analyzed by quantitative PCR using iTaq Universal SYBR green Supermix (172-5124; Bio-Rad) with primers specific to viral (IE1) (63) or cellular (GAPDH) (66) DNA. RNA isolation and quantitative reverse-transcription PCR (qRT-PCR) were performed as previously described (54). Viral gene expression was normalized to cellular gene expression using the ⌬C T method (67).…”

Section: Cells and Infectionsmentioning

confidence: 99%

“…Cells were infected with HCMV in minimal volume for 60 min, followed by addition of medium to normal culture volumes. For UV inactivation, virus stocks were exposed to a 245-nm light source at 0.12 J/cm 3 for 2 min on ice using a UV Stratalinker 2400 (Stratagene) prior to infection, as previously described (54).…”

Section: Cells and Infectionsmentioning

confidence: 99%

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Canonical and Variant Forms of Histone H3 Are Deposited onto the Human Cytomegalovirus Genome during Lytic and Latent Infections

Albright

Kalejta

2016

J Virol

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Chromatin is the nucleoprotein complex that protects and compacts eukaryotic genomes. It is responsible for a large part of the epigenetic control of transcription. The genomes of DNA viruses such as human cytomegalovirus (HCMV) are devoid of histones within virions but are chromatinized and epigenetically regulated following delivery to the host cell nucleus. How chromatin is initially assembled on viral genomes and which variant forms of the core histone proteins are deposited are incompletely understood. We monitored the deposition of both ectopically expressed and endogenous histones H3.1 and H3.2 (collectively, H3.1/2) and H3.3 during lytic and latent HCMV infections. Here, we show that they are deposited on HCMV genomes during lytic and latent infections, suggesting similar mechanisms of viral chromatin assembly during the different infection types and indicating that both canonical and variant core histones may be important modulators of infecting viral genomes. We further show that association of both H3.1/2 and H3.3 occurs independent of viral DNA synthesis or de novo viral gene expression, implicating cellular factors and/or virion components in the formation of chromatin on virion-delivered genomes during both lytic and latent infections. IMPORTANCEIt is well established that infecting herpesvirus genomes are chromatinized upon entry into the host cell nucleus. Why or how this occurs is a mystery. It is important to know why they are chromatinized in order to better understand cellular pathogen recognition (DNA sensing) pathways and viral fate determinations (lytic or latent) and to anticipate how artificially modulating chromatinization may impact viral infections. It is important to know how the genomes are chromatinized in order to potentially modulate the process for therapeutic effect. Our work showing that HCMV genomes are loaded with canonical and variant H3 histones during both lytic and latent infections strengthens the hypothesis that chromatinization pathways are similar between the two infection types, implicates virion or cellular factors in this process, and exposes the possibility that histone variants, in addition to posttranslational modification, may impact viral gene expression. These revelations are important to understanding and intelligently intervening in herpesvirus infections.T he large genomes of eukaryotic cells must be highly compacted in order to fit within the restricted volume of the nucleus. To accomplish this, eukaryotic DNA is packaged into a repeating nucleoprotein structure known as chromatin, the basic subunit of which is the nucleosome (1, 2). The core nucleosome particle consists of approximately 146 bp of DNA wrapped nearly twice around a histone hetero-octamer consisting of two copies each of the four core histone proteins H2A, H2B, H3, and H4 (3). Nucleosomes are further compacted into higher-order chromatin fibers through the incorporation of the linker histone H1, other nonhistone proteins, and structural RNA components (4-6).Wrapping DNA in nucleoso...

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Section: Resultssupporting

confidence: 54%

Section: Cells and Infectionsmentioning

confidence: 99%

Section: Cells and Infectionsmentioning

confidence: 99%

Section: Cells and Infectionsmentioning

confidence: 99%

See 2 more Smart Citations

Canonical and Variant Forms of Histone H3 Are Deposited onto the Human Cytomegalovirus Genome during Lytic and Latent Infections

Albright

Kalejta

2016

J Virol

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“…While many of the mechanisms important to productive infection are well understood in fibroblasts (3), the mechanisms critical to latency remain poorly defined. However, in the last decade, an in vitro system to model experimental HCMV latency emerged, permitting genetic (9)(10)(11)(12)(13)(14)(15) and molecular (16)(17)(18) analyses of latently infected cells. During latency, the expression of productive-phase genes is suppressed.…”

mentioning

confidence: 99%

Long and Short Isoforms of the Human Cytomegalovirus UL138 Protein Silence IE Transcription and Promote Latency

Lee

Caviness

Albright

et al. 2016

J Virol

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The UL133-138 locus present in clinical strains of human cytomegalovirus (HCMV) encodes proteins required for latency and reactivation in CD34؉ hematopoietic progenitor cells and virion maturation in endothelial cells. The encoded proteins form multiple homo-and hetero-interactions and localize within secretory membranes. One of these genes, UL136 gene, is expressed as at least five different protein isoforms with overlapping and unique functions. Here we show that another gene from this locus, the UL138 gene, also generates more than one protein isoform. A long form of UL138 (pUL138-L) initiates translation from codon 1, possesses an amino-terminal signal sequence, and is a type one integral membrane protein. Here we identify a short protein isoform (pUL138-S) initiating from codon 16 that displays a subcellular localization similar to that of pUL138-L. Reporter, short-term transcription, and long-term virus production assays revealed that both pUL138-L and pUL138-S are able to suppress major immediate early (IE) gene transcription and the generation of infectious virions in cells in which HCMV latency is studied. The long form appears to be more potent at silencing IE transcription shortly after infection, while the short form seems more potent at restricting progeny virion production at later times, indicating that both isoforms of UL138 likely cooperate to promote HCMV latency. IMPORTANCELatency allows herpesviruses to persist for the lives of their hosts in the face of effective immune control measures for productively infected cells. Controlling latent reservoirs is an attractive antiviral approach complicated by knowledge deficits for how latently infected cells are established, maintained, and reactivated. This is especially true for betaherpesviruses. The functional consequences of HCMV UL138 protein expression during latency include repression of viral IE1 transcription and suppression of virus replication. Here we show that short and long isoforms of UL138 exist and can themselves support latency but may do so in temporally distinct manners. Understanding the complexity of gene expression and its impact on latency is important for considering potential antivirals targeting latent reservoirs. Human cytomegalovirus (HCMV) is a betaherpesvirus that causes birth defects and disease in immunocompromised and immunosuppressed patients and has been associated with cancers, cardiovascular disease, and immune dysfunction (1-3). HCMV productively (lytically) infects differentiated cells, such as fibroblasts, endothelial cells, and epithelial cells, and latently infects incompletely differentiated cells of the myeloid lineage, such as monocytes and CD34 ϩ hematopoietic progenitor cells (HPC) (4, 5). Productive infection in multiple cell types within the human host facilitates viral dissemination, while latency ensures lifelong persistence despite an effective immune response against lyticphase antigens. Periodic reactivations of latent infections into the productive phase perpetuate both lifelong infecti...

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MORC3 represses the HCMV major immediate early promoter in myeloid cells in the absence of PML nuclear bodies

Champion,

Rowland,

Yee

et al. 2023

Journal of Medical Virology

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Human cytomegalovirus (HCMV) can undergo either a latent or a lytic infection in cells of the myeloid lineage. Whilst the molecular mechanisms which determine the outcome of infection are far from clear, it is well established that a key factor is the differential regulation of the major immediate early promoter (MIEP) responsible for driving lytic immediate early gene expression. Using a myelomonocytic cell line stably transduced with a GFP reporter under the control of the MIEP, which recapitulates MIEP regulation in the context of virus infection, we have used an unbiased CRISPR‐Cas9 sub‐genomic, epigenetic library screen to identify novel cellular factors involved in MIEP repression during establishment and maintenance of latency in myeloid cells. One such cellular factor identified was MORC3. Consistent with MORC3 being a robust repressor of the MIEP, we show that THP1 cells devoid of MORC3 fail to establish latency. We also show that MORC3 is induced during latent infection, recruited to the MIEP and forms MORC3 nuclear bodies (MORC3‐NBs) which, interestingly, co‐localize with viral genomes. Finally, we show that the latency‐associated functions of MORC3 are regulated by the deSUMOylase activity of the viral latency‐associated LUNA protein likely to prevent untimely HCMV reactivation.

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Cellular defense against latent colonization foiled by human cytomegalovirus UL138 protein

Abstract: Cells have a defense against latent human cytomegalovirus, but the viral UL138 protein inactivates it to allow lifelong persistence.

Cited by 57 publications

References 88 publications

Canonical and Variant Forms of Histone H3 Are Deposited onto the Human Cytomegalovirus Genome during Lytic and Latent Infections

Canonical and Variant Forms of Histone H3 Are Deposited onto the Human Cytomegalovirus Genome during Lytic and Latent Infections

Long and Short Isoforms of the Human Cytomegalovirus UL138 Protein Silence IE Transcription and Promote Latency

MORC3 represses the HCMV major immediate early promoter in myeloid cells in the absence of PML nuclear bodies

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