Dataset Information

Induction of Interferon Kappa in Human Papillomavirus 16 Infection by Transforming Growth Factor Beta-Induced Promoter Demethylation.

ABSTRACT: Persistent high-risk human papillomavirus (HPV) infection is the major causal factor in cervical and other anogenital cancers. Because there are currently no therapeutics capable of preventing neoplastic progression of HPV infections, understanding the mechanisms of HPV-mediated persistence, including immune evasion, is a major research priority. The multifunctional growth factor transforming growth factor beta (TGF?) has been shown to inhibit expression of early viral transcripts from cells harboring integrated HPV genomes or cells infected with retroviruses expressing HPV oncoproteins. However, the mechanism of TGF?-induced inhibition has not been fully defined. In this study, we have observed a previously uncharacterized ability of TGF? to repress the differentiation-induced upregulation of late HPV16 gene expression. In addition, interferon kappa (IFN-?), a keratinocyte-specific, constitutively expressed cytokine suppressed by differentiation, can be transcriptionally induced by TGF?1. TGF?-mediated IFN-? transcription only occurs in cells containing HPV16, and this is due to TGF?1-mediated reversal of HPV-induced methylation of the IFN-? promoter through active DNA demethylation mediated by thymine DNA glycosylase (TDG). This novel interaction between growth factor and innate immune signaling may shed light on the mechanisms of HPV persistence and how the virus manipulates both immune and growth factor signaling to promote its life cycle.IMPORTANCE Persistent infection by high-risk HPVs is the primary risk factor for development of HPV-induced cancers. Persistence involves viral evasion of the immune response, including the IFN response. HPV is also known to suppress TGF? signaling, which inhibits viral gene expression. Here, we show that the TGF? and IFN pathways are interrelated in the context of HPV16 infection through the upregulation of IFN-? by TGF?. The ability of TGF? to induce IFN-? promoter demethylation and transcriptional activation provides a new explanation for why HPV has evolved mechanisms to inhibit TGF? in infected cells.

SUBMITTER: Woodby BL

PROVIDER: S-EPMC5874427 | biostudies-literature | 2018 Apr

REPOSITORIES: biostudies-literature

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Induction of Interferon Kappa in Human Papillomavirus 16 Infection by Transforming Growth Factor Beta-Induced Promoter Demethylation.

Woodby Brittany L BL Songock William K WK Scott Matthew L ML Raikhy Gaurav G Bodily Jason M JM

Journal of virology 20180328 8

Persistent high-risk human papillomavirus (HPV) infection is the major causal factor in cervical and other anogenital cancers. Because there are currently no therapeutics capable of preventing neoplastic progression of HPV infections, understanding the mechanisms of HPV-mediated persistence, including immune evasion, is a major research priority. The multifunctional growth factor transforming growth factor beta (TGFβ) has been shown to inhibit expression of early viral transcripts from cells har ...[more]

PMID: 29437968

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Project description:The innate immune response is vital for host defense and must be tightly controlled, but the mechanisms responsible for its negative regulation are not fully understood. The cell growth-regulating nucleolar protein LYAR was found to promote replication of multiple viruses in our previous study. Here, we report that LYAR acts as a negative regulator of innate immune responses. We found that LYAR expression is induced by beta interferon (IFN-?) during virus infection. Further studies showed that LYAR interacts with phosphorylated IFN regulatory factor 3 (IRF3) to impede the DNA binding capacity of IRF3, thereby suppressing the transcription of IFN-? and downstream IFN-stimulated genes (ISGs). In addition, LYAR inhibits nuclear factor-?B (NF-?B)-mediated expression of proinflammatory cytokines. In summary, our study reveals the mechanism of LYAR in modulating IFN-?-mediated innate immune responses by targeting phosphorylated IRF3, which not only helps us to better understand the mechanisms of LYAR-regulated virus replication but also uncovers a novel role of LYAR in host innate immunity.IMPORTANCE Type I interferon (IFN-I) plays a critical role in the antiviral innate immune responses that protect the host against virus infection. The negative regulators of IFN-I are important not only for fine-tuning the antiviral responses to pathogens but also for preventing excessive inflammation. Identification of negative regulators and study of their modulation in innate immune responses will lead to new strategies for the control of both viral and inflammatory diseases. Here, we report for the first time that the cell growth-regulating nucleolar protein LYAR behaves as a repressor of host innate immune responses. We demonstrate that LYAR negatively regulates IFN-?-mediated immune responses by inhibiting the DNA binding ability of IFN regulatory factor 3 (IRF3). Our study reveals a common mechanism of LYAR in promoting different virus replication events and improves our knowledge of host negative regulation of innate immune responses.

Project description:Human papillomaviruses (HPVs) infect squamous epithelia and cause several important cancers. Immune evasion is critical for viral persistence. Fibroblasts in the stromal microenvironment provide growth signals and cytokines that are required for proper epithelial differentiation, maintenance, and immune responses and are critical in the development of many cancers. In this study, we examined the role of epithelial-stromal interactions in the HPV16 life cycle using organotypic (raft) cultures as a model. Rafts were created using uninfected human foreskin keratinocytes (HFKs) and HFKs containing either wild-type HPV16 or HPV16 with a stop mutation to prevent the expression of the viral oncogene E5. Microarray analysis revealed significant changes in gene expression patterns in the stroma in response to HPV16, some of which were E5 dependent. Interferon (IFN)-stimulated genes (ISGs) and extracellular matrix remodeling genes were suppressed, the most prominent pathways affected. STAT1, IFNAR1, IRF3, and IRF7 were knocked down in stromal fibroblasts using lentiviral short hairpin RNA (shRNA) transduction. HPV late gene expression and viral copy number in the epithelium were increased when the stromal IFN pathway was disrupted, indicating that the stroma helps control the late phase of the HPV life cycle in the epithelium. Increased late gene expression correlated with increased late keratinocyte differentiation but not decreased IFN signaling in the epithelium. These studies show HPV16 has a paracrine effect on stromal innate immunity, reveal a new role for E5 as a stromal innate immune suppressor, and suggest that stromal IFN signaling may influence keratinocyte differentiation.IMPORTANCE The persistence of high-risk human papillomavirus (HPV) infections is the key risk factor for developing HPV-associated cancers. The ability of HPV to evade host immunity is a critical component of its ability to persist. The environment surrounding a tumor is increasingly understood to be critical in cancer development, including immune evasion. Our studies show that HPV can suppress the expression of immune-related genes in neighboring fibroblasts in a three-dimensional (3D) model of human epithelium. This finding is significant, because it indicates that HPV can control innate immunity not only in the infected cell but also in the microenvironment. In addition, the ability of HPV to regulate stromal gene expression depends in part on the viral oncogene E5, revealing a new function for this protein as an immune evasion factor.

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Project description:Transforming growth factor-?s (TGF-?s) regulate cellular proliferation, differentiation, and survival. TGF-?s bind to type I (TGF-?RI) and II receptors (TGF-?RII), which are transmembrane kinase receptors, and an accessory type III receptor (TGF-?RIII). TGF-? may utilize another type I receptor, activin-like kinase receptor (Alk1). TGF-? is neuroprotective in the middle cerebral artery occlusion (MCAO) model of stroke. Recently, we reported the expression pattern of TGF-?1-3 after MCAO. To establish how TGF-?s exert their actions following MCAO, the present study describes the induction of TGF-?RI, RII, RIII and Alk1 at 24 h, 72 h and 1 mo after transient 1 h MCAO as well as following 24 h permanent MCAO using in situ hybridization histochemistry. In intact brain, only TGF-?RI had significant expression: neurons in cortical layer IV contained TGF-?RI. At 24 h after the occlusion, no TGF-? receptors showed induction. At 72 h following MCAO, all four types of TGF-? receptors were induced in the infarct area, while TGF-?RI and RII also appeared in the penumbra. Most cells with elevated TGF-?RI mRNA levels were microglia. TGF-?RII co-localized with both microglial and endothelial markers while TGF-?RIII and Alk1 were present predominantly in endothels. All four TGF-? receptors were induced within the lesion 1 mo after the occlusion. In particular, TGF-?RIII was further induced as compared to 72 h after MCAO. At this time point, TGF-?RIII signal was predominantly not associated with blood vessels suggesting its microglial location. These data suggest that TGF-? receptors are induced after MCAO in a timely and spatially regulated fashion. TGF-? receptor expression is preceded by increased TGF-? expression. TGF-?RI and RII are likely to be co-expressed in microglial cells while Alk1, TGF-?RII, and RIII in endothels within the infarct where TGF-?1 may be their ligand. At later time points, TGF-?RIII may also appear in glial cells to potentially affect signal transduction via TGF-?RI and RII.

Dataset Information

Induction of Interferon Kappa in Human Papillomavirus 16 Infection by Transforming Growth Factor Beta-Induced Promoter Demethylation.

Publications

Induction of Interferon Kappa in Human Papillomavirus 16 Infection by Transforming Growth Factor Beta-Induced Promoter Demethylation.

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