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Ren Y, Wang A, Zhang B, Ji W, Zhu XX, Lou J, Huang M, Qiu Y, Zhou X. Human cytomegalovirus UL36 inhibits IRF3-dependent immune signaling to counterbalance its immunoenhancement as apoptotic inhibitor. SCIENCE ADVANCES 2023; 9:eadi6586. [PMID: 37792941 PMCID: PMC10550242 DOI: 10.1126/sciadv.adi6586] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 08/31/2023] [Indexed: 10/06/2023]
Abstract
Apoptotic inhibition and immune evasion have particular importance to efficient viral infection, while a dilemma often faced by viruses is that inhibiting apoptosis can up-regulate antiviral immune signaling. Herein, we uncovered that in addition to inhibiting caspase-8/extrinsic apoptosis, human cytomegalovirus (HCMV)-encoded UL36 suppresses interferon regulatory factor 3 (IRF3)-dependent immune signaling by directly targeting IRF3 to abrogate IRF3 interaction with stimulator of interferon genes or TANK-binding kinase 1 and inhibit IRF3 phosphorylation/activation. Although UL36-mediated caspase-8/extrinsic apoptosis inhibition enhances immune signaling, the immunosuppressing activity of UL36 counterbalances this immunoenhancing "side effect" undesirable for virus. Furthermore, we used mutational analyses to show that only the wild-type, but not the UL36 mutant losing either inhibitory activity, is sufficient to support effective HCMV replication in cells, showing the functional importance of the dual inhibition by UL36 for the HCMV life cycle. Together, our findings demonstrate a sophisticated mechanism by which HCMV tightly controls innate immune signaling and extrinsic apoptosis for efficient infection.
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Affiliation(s)
- Yujie Ren
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - An Wang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Bowen Zhang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenting Ji
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
- School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Xiao-Xu Zhu
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jing Lou
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
| | - Muhan Huang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
| | - Yang Qiu
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xi Zhou
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
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Mosher BS, Kowalik TF, Yurochko AD. Overview of how HCMV manipulation of host cell intracellular trafficking networks can promote productive infection. FRONTIERS IN VIROLOGY 2022. [DOI: 10.3389/fviro.2022.1026452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Human cytomegalovirus (HCMV) is a significant cause of morbidity and mortality in the immunocompromised and developing fetuses. Infection has also been linked to chronic inflammatory diseases, cardiovascular disease, and the development of certain cancers. The wide range of pathologies associated with HCMV infection is attributable to the broad cellular tropism of the virus where infection affects every organ system. Like other viruses, HCMV must tailor host cells to support productive infection. In particular, HCMV dedicates many resources and various strategies to manipulate host intracellular trafficking networks to facilitate various aspects of infection across all infected cell types. The dysregulation of host intracellular trafficking networks allows the virus to translocate to the host cell nucleus for genome replication, facilitate nuclear import/export of viral proteins and immature virions, subvert the host immune response, form new organelles for progeny virion assembly, maturation and egress, and promote cellular migration and viral spread. However, due to their complex nature, many aspects of these processes are not well-studied. New research and omics-based technologies have recently begun to elucidate the extent to which HCMV dysregulates host cell trafficking machinery. Here we review the variety of strategies HCMV utilizes to dysregulate intracellular trafficking networks to promote productive infection.
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Dual inhibition of innate immunity and apoptosis by human cytomegalovirus protein UL37x1 enables efficient virus replication. Nat Microbiol 2022; 7:1041-1053. [DOI: 10.1038/s41564-022-01136-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 04/26/2022] [Indexed: 11/08/2022]
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O’Brien BS, Mokry RL, Schumacher ML, Pulakanti K, Rao S, Terhune SS, Ebert AD. Downregulation of neurodevelopmental gene expression in iPSC-derived cerebral organoids upon infection by human cytomegalovirus. iScience 2022; 25:104098. [PMID: 35391828 PMCID: PMC8980761 DOI: 10.1016/j.isci.2022.104098] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 01/18/2022] [Accepted: 03/15/2022] [Indexed: 11/25/2022] Open
Abstract
Human cytomegalovirus (HCMV) is a betaherpesvirus that can cause severe birth defects including vision and hearing loss, microcephaly, and seizures. Currently, no approved treatment options exist for in utero infections. Here, we aimed to determine the impact of HCMV infection on the transcriptome of developing neurons in an organoid model system. Cell populations isolated from organoids based on a marker for infection and transcriptomes were defined. We uncovered downregulation in key cortical, neurodevelopmental, and functional gene pathways which occurred regardless of the degree of infection. To test the contributions of specific HCMV immediate early proteins known to disrupt neural differentiation, we infected NPCs using a recombinant virus harboring a destabilization domain. Despite suppressing their expression, HCMV-mediated transcriptional downregulation still occurred. Together, our studies have revealed that HCMV infection causes a profound downregulation of neurodevelopmental genes and suggest a role for other viral factors in this process.
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Affiliation(s)
- Benjamin S. O’Brien
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Rebekah L. Mokry
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Megan L. Schumacher
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | | | - Sridhar Rao
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Blood Research Institute, Versiti, Milwaukee, WI 53226, USA
| | - Scott S. Terhune
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Allison D. Ebert
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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Abstract
Cellular lipid metabolism plays a pivotal role in human cytomegalovirus (HCMV) infection, as increased lipogenesis in HCMV-infected cells favors the envelopment of newly synthesized viral particles. As all cells are equipped with restriction factors (RFs) able to exert a protective effect against invading pathogens, we asked whether a similar defense mechanism would also be in place to preserve the metabolic compartment from HCMV infection. Here, we show that gamma interferon (IFN-γ)-inducible protein 16 (IFI16), an RF able to block HCMV DNA synthesis, can also counteract HCMV-mediated metabolic reprogramming in infected primary human foreskin fibroblasts (HFFs), thereby limiting virion infectivity. Specifically, we find that IFI16 downregulates the transcriptional activation of the glucose transporter 4 (GLUT4) through cooperation with the carbohydrate-response element-binding protein (ChREBP), thereby reducing HCMV-induced transcription of lipogenic enzymes. The resulting decrease in glucose uptake and consumption leads to diminished lipid synthesis, which ultimately curbs the de novo formation of enveloped viral particles in infected HFFs. Consistently, untargeted lipidomic analysis shows enhanced cholesteryl ester levels in IFI16 KO versus wild-type (WT) HFFs. Overall, our data unveil a new role of IFI16 in the regulation of glucose and lipid metabolism upon HCMV replication and uncover new potential targets for the development of novel antiviral therapies.
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Poole E, Sinclair J. Understanding HCMV Latency Using Unbiased Proteomic Analyses. Pathogens 2020; 9:E590. [PMID: 32698381 PMCID: PMC7399836 DOI: 10.3390/pathogens9070590] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 07/16/2020] [Accepted: 07/17/2020] [Indexed: 02/07/2023] Open
Abstract
Human cytomegalovirus (HCMV) establishes either a latent (non-productive) or lytic (productive) infection depending upon cell type, cytokine milieu and the differentiation status of the infected cell. Undifferentiated cells, such as precursor cells of the myeloid lineage, support a latent infection whereas terminally differentiated cells, such as monocytes or dendritic cells are an environment conducive to reactivation and support a lytic infection. The mechanisms which regulate HCMV in either a latent or lytic infection have been the focus of intense investigation with a view to developing novel treatments for HCMV-associated disease which can have a heavy clinical burden after reactivation or primary infection in, especially, the immune compromised. To this end, a number of studies have been carried out in an unbiased manner to address global changes occurring within the latently infected cell to address the molecular changes associated with HCMV latency. In this review, we will concentrate on the proteomic analyses which have been carried out in undifferentiated myeloid cells which either stably express specific viral latency associated genes in isolation or on cells which have been latently infected with virus.
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Affiliation(s)
- Emma Poole
- Department of Medicine, University of Cambridge, box 157, Level 5 Addenbrooke’s Hospital, Hills Road, Cambridge CB2 0QQ, UK;
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Lee CH, Grey F. Systems Virology and Human Cytomegalovirus: Using High Throughput Approaches to Identify Novel Host-Virus Interactions During Lytic Infection. Front Cell Infect Microbiol 2020; 10:280. [PMID: 32587832 PMCID: PMC7298070 DOI: 10.3389/fcimb.2020.00280] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 05/12/2020] [Indexed: 12/16/2022] Open
Abstract
Human Cytomegalovirus (HCMV) is a highly prevalent herpesvirus, persistently infecting between 30 and 100% of the population, depending on socio-economic status (Fields et al., 2013). HCMV remains an important clinical pathogen accounting for more than 60% of complications associated with solid organ transplant patients (Kotton, 2013; Kowalsky et al., 2013; Bruminhent and Razonable, 2014). It is also the leading cause of infectious congenital birth defects and has been linked to chronic inflammation and immune aging (Ballard et al., 1979; Griffith et al., 2016; Jergovic et al., 2019). There is currently no effective vaccine and HCMV antivirals have significant side effects. As current antivirals target viral genes, the virus can develop resistance, reducing drug efficacy. There is therefore an urgent need for new antiviral agents that are effective against HCMV, have better toxicity profiles and are less vulnerable to the emergence of resistant strains. Targeting of host factors that are critical to virus replication is a potential strategy for the development of novel antivirals that circumvent the development of viral resistance. Systematic high throughput approaches provide powerful methods for the identification of novel host-virus interactions. As well as contributing to our basic understanding of virus and cell biology, such studies provide potential targets for the development of novel antiviral agents. High-throughput studies, such as RNA sequencing, proteomics, and RNA interference screens, are useful tools to identify HCMV-induced global changes in host mRNA and protein expression levels and host factors important for virus replication. Here, we summarize new findings on HCMV lytic infection from high-throughput studies since 2014 and how screening approaches have evolved.
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Affiliation(s)
- Chen-Hsuin Lee
- Division of Infection and Immunity, Roslin Institute, The University of Edinburgh, Edinburgh, United Kingdom
| | - Finn Grey
- Division of Infection and Immunity, Roslin Institute, The University of Edinburgh, Edinburgh, United Kingdom
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Adamson CS, Nevels MM. Bright and Early: Inhibiting Human Cytomegalovirus by Targeting Major Immediate-Early Gene Expression or Protein Function. Viruses 2020; 12:v12010110. [PMID: 31963209 PMCID: PMC7019229 DOI: 10.3390/v12010110] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/07/2020] [Accepted: 01/08/2020] [Indexed: 12/11/2022] Open
Abstract
The human cytomegalovirus (HCMV), one of eight human herpesviruses, establishes lifelong latent infections in most people worldwide. Primary or reactivated HCMV infections cause severe disease in immunosuppressed patients and congenital defects in children. There is no vaccine for HCMV, and the currently approved antivirals come with major limitations. Most approved HCMV antivirals target late molecular processes in the viral replication cycle including DNA replication and packaging. “Bright and early” events in HCMV infection have not been exploited for systemic prevention or treatment of disease. Initiation of HCMV replication depends on transcription from the viral major immediate-early (IE) gene. Alternative transcripts produced from this gene give rise to the IE1 and IE2 families of viral proteins, which localize to the host cell nucleus. The IE1 and IE2 proteins are believed to control all subsequent early and late events in HCMV replication, including reactivation from latency, in part by antagonizing intrinsic and innate immune responses. Here we provide an update on the regulation of major IE gene expression and the functions of IE1 and IE2 proteins. We will relate this insight to experimental approaches that target IE gene expression or protein function via molecular gene silencing and editing or small chemical inhibitors.
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Farina A, Farina GA. Fresh Insights into Disease Etiology and the Role of Microbial Pathogens. Curr Rheumatol Rep 2016; 18:1. [PMID: 26700911 DOI: 10.1007/s11926-015-0552-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pathogens have been implicated in the initiation and/or promotion of systemic sclerosis (scleroderma, SSc); however, no evidence was found to substantiate the direct contribution to this disease in past years. Recently, significant advances have been made in understanding the role of the innate immune system in SSc pathogenesis, supporting the idea that pathogens might interact with host innate immune-regulatory responses in SSc. In light of these findings, we review the studies that identified the presence of pathogens in SSc, along with studies on pathogens implicated in driving the innate immune dysregulation in SSc. The goal of this review is to illustrate how these pathogens, specifically viruses, may play important role both as triggers of the innate immune system, and critical players in the development of SSc disease.
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Affiliation(s)
- Antonella Farina
- Institute Pasteur-Fondazione Cenci Bolognetti, Department of Experimental Medicine, "Sapienza", University of Rome, Rome, Italy.
| | - G Alessandra Farina
- Arthritis Center, Department of Rheumatology, Boston University, 72 East Concord Street, E501, Boston, MA, 02118, USA.
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Harwardt T, Lukas S, Zenger M, Reitberger T, Danzer D, Übner T, Munday DC, Nevels M, Paulus C. Human Cytomegalovirus Immediate-Early 1 Protein Rewires Upstream STAT3 to Downstream STAT1 Signaling Switching an IL6-Type to an IFNγ-Like Response. PLoS Pathog 2016; 12:e1005748. [PMID: 27387064 PMCID: PMC4936752 DOI: 10.1371/journal.ppat.1005748] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 06/16/2016] [Indexed: 12/24/2022] Open
Abstract
The human cytomegalovirus (hCMV) major immediate-early 1 protein (IE1) is best known for activating transcription to facilitate viral replication. Here we present transcriptome data indicating that IE1 is as significant a repressor as it is an activator of host gene expression. Human cells induced to express IE1 exhibit global repression of IL6- and oncostatin M-responsive STAT3 target genes. This repression is followed by STAT1 phosphorylation and activation of STAT1 target genes normally induced by IFNγ. The observed repression and subsequent activation are both mediated through the same region (amino acids 410 to 445) in the C-terminal domain of IE1, and this region serves as a binding site for STAT3. Depletion of STAT3 phenocopies the STAT1-dependent IFNγ-like response to IE1. In contrast, depletion of the IL6 receptor (IL6ST) or the STAT kinase JAK1 prevents this response. Accordingly, treatment with IL6 leads to prolonged STAT1 instead of STAT3 activation in wild-type IE1 expressing cells, but not in cells expressing a mutant protein (IE1dl410-420) deficient for STAT3 binding. A very similar STAT1-directed response to IL6 is also present in cells infected with a wild-type or revertant hCMV, but not an IE1dl410-420 mutant virus, and this response results in restricted viral replication. We conclude that IE1 is sufficient and necessary to rewire upstream IL6-type to downstream IFNγ-like signaling, two pathways linked to opposing actions, resulting in repressed STAT3- and activated STAT1-responsive genes. These findings relate transcriptional repressor and activator functions of IE1 and suggest unexpected outcomes relevant to viral pathogenesis in response to cytokines or growth factors that signal through the IL6ST-JAK1-STAT3 axis in hCMV-infected cells. Our results also reveal that IE1, a protein considered to be a key activator of the hCMV productive cycle, has an unanticipated role in tempering viral replication. Our previous work has shown that the human cytomegalovirus (hCMV) major immediate-early 1 protein (IE1) modulates host cell signaling pathways involving proteins of the signal transducer and activator of transcription (STAT) family. IE1 has also long been known to facilitate viral replication by activating transcription. In this report we demonstrate that IE1 is as significant a repressor as it is an activator of host gene expression. Many genes repressed by IE1 are normally induced via STAT3 signaling triggered by interleukin 6 (IL6) or related cytokines, whereas many genes activated by IE1 are normally induced via STAT1 signaling triggered by interferon gamma (IFNγ). Our results suggest that the repression of STAT3- and the activation of STAT1-responsive genes by IE1 are coupled. By targeting STAT3, IE1 rewires upstream STAT3 to downstream STAT1 signaling. Consequently, genes normally induced by IL6 are repressed while genes normally induced by IFNγ become responsive to IL6 in the presence of IE1. We also demonstrate that, by switching an IL6 to an IFNγ-like response, IE1 tempers viral replication. These results suggest an unanticipated dual role for IE1 in either promoting or limiting hCMV propagation and demonstrate how a key viral regulatory protein merges two central cellular signaling pathways to divert cytokine responses relevant to hCMV pathogenesis.
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Affiliation(s)
- Thomas Harwardt
- Institute for Medical Microbiology and Hygiene, University of Regensburg, Regensburg, Germany
| | - Simone Lukas
- Institute for Medical Microbiology and Hygiene, University of Regensburg, Regensburg, Germany
| | - Marion Zenger
- Institute for Medical Microbiology and Hygiene, University of Regensburg, Regensburg, Germany
| | - Tobias Reitberger
- Institute for Medical Microbiology and Hygiene, University of Regensburg, Regensburg, Germany
| | - Daniela Danzer
- Institute for Medical Microbiology and Hygiene, University of Regensburg, Regensburg, Germany
| | - Theresa Übner
- Institute for Medical Microbiology and Hygiene, University of Regensburg, Regensburg, Germany
| | - Diane C. Munday
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, United Kingdom
| | - Michael Nevels
- Institute for Medical Microbiology and Hygiene, University of Regensburg, Regensburg, Germany
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, United Kingdom
- * E-mail: (MN); (CP)
| | - Christina Paulus
- Institute for Medical Microbiology and Hygiene, University of Regensburg, Regensburg, Germany
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, United Kingdom
- * E-mail: (MN); (CP)
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