US28: HCMV’s Swiss Army Knife

Krishna, Benjamin A.; Miller, William E.; O’Connor, Christine M.

doi:10.3390/v10080445

Cited by 53 publications

(57 citation statements)

References 173 publications

(280 reference statements)

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“…Furthermore, when examined, these US28-mediated effects on cell signalling did not occur during lytic infection or in permissive cells 21 , implying that US28 represses the MIEP during latency but does not impair reactivation following cellular differentiation. This is reflective of the cell type-specific nature of US28-mediated signalling 21,26 .…”

Section: Introductionmentioning

confidence: 92%

Interferon-responsive genes are targeted during the establishment of human cytomegalovirus latency

Krishna

Williamson

Lim

et al. 2019

Preprint

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12Human cytomegalovirus (HCMV) latency is an active process which remodels the latently infected 13 cell to optimise latent carriage and reactivation. This is achieved, in part, through the expression of 14 viral genes, including the G-protein coupled receptor US28. Here, we use an unbiased proteomic 15 screen to assess changes in host proteins induced by US28, revealing that interferon-inducible genes 16 are downregulated by US28. We validate that MHC Class II and two PYHIN proteins, MNDA and 17 IFI16, are downregulated during experimental latency in primary human CD14 + monocytes. We find 18 that IFI16 is targeted rapidly during the establishment of latency in a US28-dependent manner, but 19 only in undifferentiated myeloid cells, a natural site of latent carriage. Finally, by overexpressing 20 IFI16, we show that IFI16 can activate the viral major immediate early promoter and immediate early 21 2 gene expression during latency via NF-κB, a function which explains why downregulation of IFI16 22 during latency is advantageous for the virus. 23 Importance 24 Human cytomegalovirus (HCMV) is a ubiquitous herpesvirus which infects 50-100% of humans 25 worldwide. HCMV causes a lifelong subclinical infection in immunocompetent individuals, but is a 26 serious cause of mortality and morbidity in the immunocompromised and in neonates. In particular, 27 reactivation of HCMV in the transplant setting is a major cause of transplant failure and related 28 disease. Therefore, a molecular understanding of HCMV latency and reactivation could provide 29 insights into potential ways to target the latent viral reservoir in at-risk patient populations. 30 31 both host and viral factors 18 . One viral factor that suppresses MIEP activity is the G-protein coupled 46 receptor (GPCR) US28, a virally encoded chemokine receptor homologue, which is expressed de 47 novo during latency as well as being delivered to cells with the incoming virion 19-24 and this 48 incoming viral US28 is functional 25 . US28 modulates the signalling pathways of early myeloid cells; it 49 attenuates MAP kinases, NF-κB, and c-fos, whilst activating STAT3 and iNOS 21,23,25 . All of these 50 contribute to the repression of MIEP activity. This US28-mediated signalling is so critical to latency 51 that US28-deleted viruses, or the loss of G-protein coupling by the US28 mutant R129A, result in lytic 52 infection of undifferentiated myeloid cells 19,21,23,25 . Furthermore, when examined, these US28-53 mediated effects on cell signalling did not occur during lytic infection or in permissive cells 21 , 54 implying that US28 represses the MIEP during latency but does not impair reactivation following 55 cellular differentiation. This is reflective of the cell type-specific nature of US28-mediated signalling 56 21,26 . 57Since US28 can modulate all these pathways and control the MIEP, we hypothesised that US28 58 would also cause changes in host protein expression. Here, we perform a proteomic screen 59 comparing host cell protein abundance in myelomonocytic TH...

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Section: Introductionmentioning

confidence: 92%

Interferon-responsive genes are targeted during the establishment of human cytomegalovirus latency

Krishna

Williamson

Lim

et al. 2019

Preprint

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“…A second viral gene product, US28, encodes for a GPCR that can modulate cell signaling pathways during both latent and lytic infection [56,57]. Fascinatingly, US28 can either repress or activate the same pathways in a cell type-specific manner providing HCMV with molecular tool to hijack and re-direct host cell signaling [58].…”

Section: Viral Functions Manipulating Cell Signalingmentioning

confidence: 99%

Cell signaling and cytomegalovirus reactivation: what do Src family kinases have to do with it?

Reeves

2020

Biochemical Society Transactions

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Primary infection with human cytomegalovirus (HCMV) is usually asymptomatic and leads to the establishment of lifelong latent infection. A major site of latency are the CD34+ hematopoietic progenitor cells. Importantly, normal cellular differentiation of CD34+ cells to a macrophage or dendritic cell phenotype is concomitant with viral reactivation. Molecular studies of HCMV latency have shown that the latent viral genome is associated with histone proteins and that specific post-translational modifications of these histones correlates with the transcriptional activity of the genome arguing that expression of key viral genes that dictate latency and reactivation are subject to the rules of the histone code hypothesis postulated for the regulation of eukaryotic gene expression. Finally, many studies now point to a key role for multiple signaling pathways to provide the cue for HCMV reactivation. The challenge now is to understand the complex interplay between cell identity, transcriptional regulation and cell signaling that occurs to promote reactivation and, additionally, how HCMV may further manipulate these events to support reactivation. Understanding how HCMV utilizes these pathways to drive HCMV reactivation will provide new insight into the mechanisms that govern viral and host gene expression and, potentially, illuminate new, host-directed, therapeutic opportunities to support our attempts to control this important medical pathogen of immune-compromised individuals.

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“…Viral BAC DNA was isolated as described previously (32). Viral BAC DNA and the HCMV pp71-expressing plasmid, pCGN1-pp71 (1 μg) (33) were transfected into low passage MRC5 cells by electroporation, transferred to 10 cm dishes and incubated at 37°C/5% CO 2 overnight.…”

Section: Methodsmentioning

confidence: 99%

Protein S-nitrosylation of Human Cytomegalovirus pp71 inhibits its ability to limit STING antiviral responses

Nukui

Roche²,

Jia

et al. 2020

Preprint

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Human Cytomegalovirus (HCMV) is a ubiquitous pathogen that has co-evolved with its host and in doing so, is highly efficient in undermining antiviral responses that limit successful infections. As a result, HCMV infections are highly problematic in individuals with weakened or underdeveloped immune systems including transplant recipients and newborns. Understanding how HCMV controls the microenvironment of an infected cell so as to favor productive replication is of critical importance. To this end, we took an unbiased proteomics approach to identify the highly reversible, stress induced, post-translational modification (PTM), protein S-nitrosylation, on viral proteins to determine the biological impact on viral replication.We identified protein S-nitrosylation of 13 viral proteins during infection of highly permissive fibroblasts. One of these proteins, pp71, is critical for efficient viral replication, as it undermines host antiviral responses, including STING activation. By exploiting site-directed mutagenesis of the specific amino acids we identified in pp71 as protein S-nitrosylated, we found this pp71 PTM diminishes its ability to undermine antiviral responses induced by the STING pathway. Our results suggest a model in which protein S-nitrosylation may function as a host response to viral infection that limits viral spread.IMPORTANCEIn order for a pathogen to establish a successful infection, it must undermine the host cell responses inhibitory to the pathogen. As such, herpesviruses encode multiple viral proteins that antagonize each host antiviral response, thereby allowing for efficient viral replication. Human Cytomegalovirus encodes several factors that limit host countermeasures to infection, including pp71. We identified a previously unreported modification of pp71 residues within the protein are protein S-nitrosylated. Using site-directed mutagenesis, we mutated the specific sites of this modification thereby blocking this pp71 post-translational modification. In contexts where pp71 is not protein S-nitrosylated, host antiviral response was inhibited. The net result of this post-translational modification is to render a viral protein with diminished abilities to block host responses to infection. This novel work supports a model in which protein S-nitrosylation may be an additional mechanism in which a cell inhibits a pathogen during the course of infection.

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US28: HCMV’s Swiss Army Knife

Cited by 53 publications

References 173 publications

Interferon-responsive genes are targeted during the establishment of human cytomegalovirus latency

Interferon-responsive genes are targeted during the establishment of human cytomegalovirus latency

Cell signaling and cytomegalovirus reactivation: what do Src family kinases have to do with it?

Protein S-nitrosylation of Human Cytomegalovirus pp71 inhibits its ability to limit STING antiviral responses

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