Inhibition of cellular STAT3 synergizes with the cytomegalovirus kinase inhibitor maribavir to disrupt infection

Reitsma, Justin M.; Terhune, Scott S.

doi:10.1016/j.antiviral.2013.09.011

Cited by 10 publications

(5 citation statements)

References 41 publications

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“…In contrast, inhibition of STAT1 (Fludarabine) or STAT3 (S3I-201) decreased virus production. Loss of viral replication by STAT inhibition has previously been reported with these and similar inhibitors [32, 33] and is not due to a loss in cell viability (S3 Fig). Inhibition of MEK1/2 (Binimetinib), ERK1/2 (SCH772984), or PLCγ (U73122) did not alter virus titers relative to the vehicle control.…”

Section: Resultssupporting

confidence: 80%

Host signaling and EGR1 transcriptional control of human cytomegalovirus replication and latency

et al. 2019

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Sustained phosphotinositide3-kinase (PI3K) signaling is critical to the maintenance of alpha and beta herpesvirus latency. We have previously shown that the beta-herpesvirus, human cytomegalovirus (CMV), regulates epidermal growth factor receptor (EGFR), upstream of PI3K, to control states of latency and reactivation. How signaling downstream of EGFR is regulated and how this impacts CMV infection and latency is not fully understood. We demonstrate that CMV downregulates EGFR early in the productive infection, which blunts the activation of EGFR and its downstream pathways in response to stimuli. However, CMV infection sustains basal levels of EGFR and downstream pathway activity in the context of latency in CD34+ hematopoietic progenitor cells (HPCs). Inhibition of MEK/ERK, STAT or PI3K/AKT pathways downstream of EGFR increases viral reactivation from latently infected CD34+ HPCs, defining a role for these pathways in latency. We hypothesized that CMV modulation of EGFR signaling might impact viral transcription important to latency. Indeed, EGF-stimulation increased expression of the UL138 latency gene, but not immediate early or early viral genes, suggesting that EGFR signaling promotes latent gene expression. The early growth response-1 (EGR1) transcription factor is induced downstream of EGFR signaling through the MEK/ERK pathway and is important for the maintenance of hematopoietic stemness. We demonstrate that EGR1 binds the viral genome upstream of UL138 and is sufficient to promote UL138 expression. Further, disruption of EGR1 binding upstream of UL138 prevents the establishment of latency in CD34+ HPCs. Our results indicate a model whereby UL138 modulation of EGFR signaling feeds back to promote UL138 gene expression and suppression of replication for latency. By this mechanism, the virus has hardwired itself into host cell biology to sense and respond to changes in homeostatic host cell signaling.

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Section: Resultssupporting

confidence: 80%

Host signaling and EGR1 transcriptional control of human cytomegalovirus replication and latency

et al. 2019

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“…In contrast, inhibition of STAT1 (Fludarabine) or STAT3 (S3I-201) decreased virus production. Loss of viral replication by STAT inhibition has previously been reported with these and similar inhibitors (28, 29). The diminishment of virus replication was not related to cytotoxicity, as the monolayers stayed intact.…”

Section: Resultssupporting

confidence: 62%

EGR1 transcriptional control of human cytomegalovirus latency

Buehler

Carpenter

Zeltzer

et al. 2019

Preprint

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34Sustained phosphotinositide3-kinase (PI3K) signaling is critical to the maintenance of 35 herpesvirus latency. We have previously shown that the beta-herpesvirus, human 36 cytomegalovirus (CMV), regulates epidermal growth factor receptor (EGFR), upstream of PI3K, 37 to control states of latency and reactivation. Inhibition of EGFR signaling enhances CMV 38 reactivation from latency and increases viral replication, but the mechanisms by which EGFR 39 impacts replication and latency is not known. We demonstrate that HCMV downregulates 40 MEK/ERK and AKT phosphorylation, but not STAT3 or PLCγ for productive replication. 41Similarly, inhibition of either MEK/ERK or PI3K/AKT, but not STAT or PLCγ, pathways increases 42 viral reactivation from latently infected CD34 + hematopoietic progenitor cells (HPCs), defining a 43 role for these pathways in latency. We hypothesized that CMV modulation of EGFR signaling 44 might impact viral transcription. Indeed, EGF-stimulation increased expression of the UL138 45 latency gene, but not immediate early or early viral genes, suggesting that EGFR signaling 46 promotes latent gene expression. The early growth response-1 (EGR1) transcription factor is 47 induced downstream of EGFR signaling through both PI3K/AKT and MEK/ERK pathways. 48 EGR1 expression is important for the maintenance of HPC stemness and its downregulation 49 drives HPC differentiation and mobilization. We demonstrate that EGR1 binds upstream of 50 UL138 and is sufficient to promote UL138 expression. Further, disruption of EGR1 binding 51 upstream of UL138 prevented CMV from establishing a latent infection in CD34 + HPCs. Our 52 results indicate a model whereby UL138 modulation of EGFR signaling feeds back to promote 53 UL138 expression and suppression of replication to establish or maintain viral quiescence. 54 55 AUTHOR SUMMARY 56 Buehler et al. 3CMV regulates EGFR signaling to balance states of viral latency and replication. CMV blocks 57 downstream PI3K/AKT and MEK/ERK signaling pathways through down-regulation of EGFR at 58 the plasma membrane. PI3K/AKT and MEK/ERK signaling increases expression of the EGR1 59 transcription factor that is necessary for the maintenance of stem cell stemness. A decrease in 60 EGR1 expression promotes HPC mobilization to the periphery and differentiation, a known 61 stimulus for CMV reactivation. We identified functional EGR1 binding sites upstream of the 62 UL138 gene and EGR-1 binding stimulates UL138 expression. Additionally, down-regulation of 63 EGR1 by CMV miR-US22 decreases UL138 expression emphasizing the importance of this 64 transcription factor in expression of this latency gene. Lastly, we demonstrate that a CMV 65 mutant virus lacking an upstream EGR1 binding site is unable to establish latency in CD34 + 66HPCs. This study defines one mechanism by which EGFR signaling impacts viral gene 67 expression to promote CMV latency. 68 69 RESULTS 129CMV downregulates total and cell surface levels of EGFR. We previously demonstrated that 130 CMV modulates EGFR total and cell s...

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“…Other mechanisms include STAT1 "sequestration" in STAT1:STAT3 heterodimers rather than antiviral STAT1 2 dimers (40) and IFN-I signaling suppression via functionally cooperative interactions of STAT3, via its N-terminal domain and independently of DNA binding, with the transcriptional repressor phospholipid scramblase 2, which targets IFN-I-activated ISGF3 (STAT1:STAT2:IRF9)induced genes (41,42). Proreplication activities of STAT3, in part revealed by effects of STAT3 inhibitors, have been reported for other viruses, including the herpesviruses varicella-zoster virus and human cytomegalovirus (HCMV) (43,44), although HCMV blocks activating phosphorylation of STAT3 and the viral IE1 protein sequesters it in the nucleus (45). Although the mechanisms of STAT3 contributions to productive replication of these viruses and HHV-8 are undetermined, positive regulation of cell survival via induction of STAT3-responsive genes, such as survivin, Mcl-1, and Bcl-2, in addition to induction of IFN signaling inhibitors and suppression of innate immune responses by repressor-associated STAT3, may be involved.…”

Section: Discussionmentioning

confidence: 99%

Genetic Analyses of Contributions of Viral Interleukin-6 Interactions and Signaling to Human Herpesvirus 8 Productive Replication

Xiang

Chen

et al. 2020

J Virol

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Human herpesvirus 8 (HHV-8) viral interleukin-6 (vIL-6) is a cytokine that is poorly secreted and largely localized to the endoplasmic reticulum (ER). It has been implicated, along with other HHV-8 pro-inflammatory and/or angiogenic viral proteins, in HHV-8-associated Kaposi's sarcoma, primary effusion lymphoma (PEL), and multicentric Castleman's disease (MCD), in addition to an MCD-related disorder involving systemic elevation of pro-inflammatory cytokines, including vIL-6 and human IL-6 (hIL-6). In these diseases, lytic (productive) replication, in addition to viral latency, is believed to play a critical role. Pro-replication activity of vIL-6 has been identified experimentally in PEL and endothelial cells, but the relative contributions of different vIL-6 interactions have not been established. Productive interactions of vIL-6 with the IL-6 signal transducer, gp130, can occur within the ER, but vIL-6 also interacts in the ER with a non-signaling receptor called vitamin K epoxide reductase complex subunit 1 variant-2 (VKORC1v2), calnexin, and VKORC1v2- and calnexin-associated proteins UDP-glucose:glycoprotein glucosyltransferase 1 (UGGT1) and glucosidase II (GlucII). Here, we report the systematic characterization of interaction-altered vIL-6 variants and the lytic phenotypes of recombinant viruses expressing selected variants. Our data identify the critical importance of vIL-6 and its ER-localized activity via gp130 to productive replication in iSLK (inducible epithelial) cells, absence of detectable involvement of vIL-6 interactions with VKORC1v2, GlucII or UGGT1, and the insufficiency and lack of direct contributory effects of extracellular signaling by vIL-6 or hIL-6. These findings, obtained through genetics-based approaches, complement and extend previous analyses of vIL-6 activity. IMPORTANCE Human herpesvirus 8 (HHV-8)-encoded viral interleukin-6 (vIL-6) was the first viral IL-6 homologue to be identified. Experimental and clinical evidence suggests that vIL-6 is important for the onset and/or progression of HHV-8-associated endothelial- and B-cell pathologies, including AIDS-associated Kaposi's sarcoma and multicentric Castleman's disease. The protein is unusual in its poor secretion from cells and its intracellular activity; it interacts, directly or indirectly, with a number of proteins beyond the IL-6 signal transducer, gp130, and can mediate activities through these interactions in the endoplasmic reticulum. Here, we characterize with respect to protein interactions and signal transducing activity a panel of vIL-6 variants and utilize HHV-8 mutant viruses expressing selected variants in phenotypic analyses. Our findings establish the importance of vIL-6 in HHV-8 productive replication and the contributions of individual vIL-6-protein interactions to HHV-8 lytic biology. This work furthers understanding of the biological significance of vIL-6 and its unique intracellular interactions.

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Inhibition of cellular STAT3 synergizes with the cytomegalovirus kinase inhibitor maribavir to disrupt infection

Cited by 10 publications

References 41 publications

Host signaling and EGR1 transcriptional control of human cytomegalovirus replication and latency

Host signaling and EGR1 transcriptional control of human cytomegalovirus replication and latency

EGR1 transcriptional control of human cytomegalovirus latency

Genetic Analyses of Contributions of Viral Interleukin-6 Interactions and Signaling to Human Herpesvirus 8 Productive Replication

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