-
Cell Death & Disease Sep 2023Phosphorylation of IRF3 is critical to induce type I interferon (IFN-I) production in antiviral innate response. Here we report that lysine methyltransferase SMYD2...
Phosphorylation of IRF3 is critical to induce type I interferon (IFN-I) production in antiviral innate response. Here we report that lysine methyltransferase SMYD2 inhibits the expressions of IFN-I and proinflammatory cytokines in macrophages upon viral infections. The Smyd2-deficient mice are more resistant to viral infection by producing more IFN-I and proinflammatory cytokines. Mechanistically, SMYD2 inhibits IRF3 phosphorylation in macrophages in response to viral infection independent of its methyltransferase activity. We found that SMYD2 interacts with the DNA-binding domain (DBD) and IRF association domain (IAD) domains of IRF3 by its insertion SET domain (SETi) and could recruit phosphatase PP1α to enhance its interaction with IRF3, which leads to decreased phosphorylation of IRF3 in the antiviral innate response. Our study identifies SMYD2 as a negative regulator of IFN-I production against virus infection. The new way of regulating IRF3 phosphorylation will provide insight into the understanding of IFN-I production in the innate response and possible intervention of the related immune disorders.
Topics: Animals; Mice; Antiviral Agents; Lysine; Immunity, Innate; Interferons; Cytokines; Antibodies; Methyltransferases
PubMed: 37673879
DOI: 10.1038/s41419-023-06118-y -
PLoS Pathogens Jul 2023Deubiquitinating enzymes (DUBs) regulate antiviral immune response through targeting DNA sensor signaling pathway members. As one of the DNA sensors, interferon (IFN)-γ...
Deubiquitinating enzymes (DUBs) regulate antiviral immune response through targeting DNA sensor signaling pathway members. As one of the DNA sensors, interferon (IFN)-γ inducible protein 16 (IFI16) play a major role in response to virus infections through activating the canonical STING/TBK-1/IRF3 signaling pathway. Only a few studies discuss the function of DUBs in IFI16-mediated antiviral response. Ubiquitin-specific protease 12 (USP12), which is one of the major members of the USP family, participates in various biological functions. However, whether USP12 regulates the nucleic acid sensor to modulate antiviral immune responses has not yet been elucidated. In this study, we found that knockout or knockdown of USP12 impaired the HSV-1-induced expressions of IFN-β, CCL-5, IL-6, and downstream interferon-stimulated genes (ISGs). Moreover, USP12 deficiency increased HSV-1 replication and host susceptibility to HSV-1 infection. Mechanistically, USP12 inhibited the proteasome-dependent degradation of IFI16 through its deubiquitinase activity, thereby maintaining IFI16 stability and promoting IFI16-STING-IRF3- and p65-mediated antiviral signaling. Overall, our findings demonstrate an essential role of USP12 in DNA-sensing signaling and contribute to the understanding of deubiquitination-mediated regulation of innate antiviral responses.
Topics: Humans; Phosphoproteins; Herpesvirus 1, Human; Herpes Simplex; Interferons; Antiviral Agents; Immunity, Innate; Ubiquitin Thiolesterase; Nuclear Proteins
PubMed: 37410794
DOI: 10.1371/journal.ppat.1011480 -
PLoS Pathogens Nov 2023Melanoma differentiation-associated gene-5 (MDA5) acts as a cytoplasmic RNA sensor to detect viral dsRNA and mediates antiviral innate immune responses to infection by...
Melanoma differentiation-associated gene-5 (MDA5) acts as a cytoplasmic RNA sensor to detect viral dsRNA and mediates antiviral innate immune responses to infection by RNA viruses. Upon recognition of viral dsRNA, MDA5 is activated with K63-linked polyubiquitination and then triggers the recruitment of MAVS and activation of TBK1 and IKKα/β, subsequently leading to IRF3 and NF-κB phosphorylation. However, the specific E3 ubiquitin ligase for MDA5 K63-polyubiquitination has not been well characterized. Great numbers of symptomatic and severe infections of SARS-CoV-2 are spreading worldwide, and the poor efficacy of treatment with type I interferon and antiviral immune agents indicates that SARS-CoV-2 escapes from antiviral immune responses via several unknown mechanisms. Here, we report that SARS-CoV-2 nonstructural protein 8 (nsp8) acts as a suppressor of antiviral innate immune and inflammatory responses to promote infection of SARS-CoV-2. It downregulates the expression of type I interferon, IFN-stimulated genes and proinflammatory cytokines by binding to MDA5 and TRIM4 and impairing TRIM4-mediated MDA5 K63-linked polyubiquitination. Our findings reveal that nsp8 mediates innate immune evasion during SARS-CoV-2 infection and may serve as a potential target for future therapeutics for SARS-CoV-2 infectious diseases.
Topics: Humans; COVID-19; Immunity, Innate; Interferon Type I; Interferon-Induced Helicase, IFIH1; SARS-CoV-2; Signal Transduction
PubMed: 37956198
DOI: 10.1371/journal.ppat.1011792 -
Frontiers in Immunology 2023Epstein-Barr virus (EBV) and human herpesvirus 6 (HHV-6) have been associated with multiple sclerosis (MS). Teriflunomide is an oral disease-modifying therapy approved...
BACKGROUND
Epstein-Barr virus (EBV) and human herpesvirus 6 (HHV-6) have been associated with multiple sclerosis (MS). Teriflunomide is an oral disease-modifying therapy approved for treatment of relapsing forms of MS. In the preclinical Theiler's murine encephalitis virus model of MS, the drug demonstrated an increased rate of viral clearance versus the vehicle placebo. Furthermore, teriflunomide inhibits lytic EBV infection .
OBJECTIVE
1. To evaluate the humoral response against EBV and HHV-6 prior to teriflunomide treatment and 6 months later. 2. To correlate the variation in the humoral response against EBV and HHV-6 with the clinical and radiological response after 24 months of treatment with teriflunomide. 3. To analyze the utility of different demographic, clinical, radiological, and environmental data to identify early biomarkers of response to teriflunomide.
METHODS
A total of 101 MS patients (62 women; mean age: 43.4 years) with one serum prior to teriflunomide onset and another serum sample 6 months later were recruited. A total of 80 had been treated for at least 24 months, 13 had stopped teriflunomide before 24 months, and 8 were currently under teriflunomide therapy but with less than 24 months of follow-up. We analyzed the levels of the viral antibodies titers abovementioned in serum samples with ELISA commercial kits, and the levels of serum neurofilament light chain (Nf-L).
RESULTS
Antiviral antibody titers decreased for EBNA-1 IgG (74.3%), VCA IgG (69%), HHV-6 IgG (60.4%), and HHV-6 IgM (73.3%) after 6 months of teriflunomide. VCA IgG titers at baseline correlated with Nf-L levels measured at the same time (r = 0.221; p = 0.028) and 6 months later (r = 0.240; p = 0.017). We found that higher EBNA-1 titers (p = 0.001) and a higher age (p = 0.04) at baseline were associated with NEDA-3 conditions. Thus, 77.8% of patients with EBNA-1 >23.0 AU and >42.8 years (P50 values) were NEDA-3.
CONCLUSION
Treatment with teriflunomide was associated with a reduction of the levels of IgG antibody titers against EBV and HHV-6. Furthermore, higher EBNA-1 IgG titers prior to teriflunomide initiation were associated with a better clinical response.
Topics: Humans; Female; Animals; Mice; Adult; Herpesvirus 4, Human; Multiple Sclerosis; Epstein-Barr Virus Infections; Antigens, Viral; Capsid Proteins; Antibodies, Viral; Immunoglobulin G; Antiviral Agents
PubMed: 37841253
DOI: 10.3389/fimmu.2023.1248182 -
La Tunisie Medicale Mar 2024The impact of direct antiviral drugs (DAAs) on extrahepatic manifestations in chronic hepatitis C (CHC) has been poorly studied.
INTRODUCTION
The impact of direct antiviral drugs (DAAs) on extrahepatic manifestations in chronic hepatitis C (CHC) has been poorly studied.
AIM
To assess the prevalence of subclinical atherosclerosis in patients with CHC and the impact of DAAs on atherosclerotic lesions. Methods A 5-year prospective evaluative study, including patients followed for CHC at hepato-gastroenterology department. The subclinical atherosclerosis was assessed by ultrasound measurement of carotid intima-media thickness (IMTc) and the highest IMTc measurements from the left and right side defined the IMTc maximum (IMTc max). IMTc>75th percentile (IMTc75) define subclinical atherosclerosis with high cardiovascular risk. Patients were evaluated before (T0) and one year after DAAs therapy achievement (T1).
RESULTS
At time T0, forty patients (median age: 55 y.; sex ratio M / F = 0.48), were included. Average value of IMTc max was 0.68 ± 0.16 mm. Subclinical atherosclerosis was noted in 82.5 %. At time T1, 28 patients were evaluated, all of whom completed sustained virological response (SVR). Compared to time T0, there was a significant increase in cholesterol (p = 0.001) and triglyceride (p = 0.009) levels. IMTc max was significantly higher at time T1 compared to T0 (0.75 Vs 0.67 mm, p = 0.04). Prevalence of IMTc75 was 82.1% at time T0 and 75% at time T1 (p=0.5).
CONCLUSIONS
SVR, in CHC patients treated with DAA, was associated with worsening of carotid atherosclerotic lesions.
Topics: Humans; Middle Aged; Antiviral Agents; Hepatitis C, Chronic; Carotid Intima-Media Thickness; Prospective Studies; Atherosclerosis
PubMed: 38545713
DOI: 10.62438/tunismed.v102i3.4601 -
International Journal of Molecular... Sep 2023Infection with Ebola virus (EBOV) is responsible for hemorrhagic fever in humans with a high mortality rate. Combined efforts of prevention and therapeutic intervention...
Infection with Ebola virus (EBOV) is responsible for hemorrhagic fever in humans with a high mortality rate. Combined efforts of prevention and therapeutic intervention are required to tackle highly variable RNA viruses, whose infections often lead to outbreaks. Here, we have screened the 2P2I chemical library using a nanoluciferase-based protein complementation assay (NPCA) and isolated two compounds that disrupt the interaction of the EBOV protein fragment VP35IID with the N-terminus of the dsRNA-binding proteins PKR and PACT, involved in IFN response and/or intrinsic immunity, respectively. The two compounds inhibited EBOV infection in cell culture as well as infection by measles virus (MV) independently of IFN induction. Consequently, we propose that the compounds are antiviral by restoring intrinsic immunity driven by PACT. Given that PACT is highly conserved across mammals, our data support further testing of the compounds in other species, as well as against other negative-sense RNA viruses.
Topics: Humans; Animals; Hemorrhagic Fever, Ebola; Ebolavirus; Antiviral Agents; Mammals
PubMed: 37834238
DOI: 10.3390/ijms241914791 -
EMBO Reports Sep 2023Interferons control viral infection by inducing the expression of antiviral effector proteins encoded by interferon-stimulated genes (ISGs). The field has mostly focused...
Interferons control viral infection by inducing the expression of antiviral effector proteins encoded by interferon-stimulated genes (ISGs). The field has mostly focused on identifying individual antiviral ISG effectors and defining their mechanisms of action. However, fundamental gaps in knowledge about the interferon response remain. For example, it is not known how many ISGs are required to protect cells from a particular virus, though it is theorized that numerous ISGs act in concert to achieve viral inhibition. Here, we used CRISPR-based loss-of-function screens to identify a markedly limited set of ISGs that confer interferon-mediated suppression of a model alphavirus, Venezuelan equine encephalitis virus (VEEV). We show via combinatorial gene targeting that three antiviral effectors-ZAP, IFIT3, and IFIT1-together constitute the majority of interferon-mediated restriction of VEEV, while accounting for < 0.5% of the interferon-induced transcriptome. Together, our data suggest a refined model of the antiviral interferon response in which a small subset of "dominant" ISGs may confer the bulk of the inhibition of a given virus.
Topics: Animals; Horses; Interferons; Cell Line; Virus Replication; Antiviral Agents; Encephalitis Virus, Venezuelan Equine; Viruses
PubMed: 37497756
DOI: 10.15252/embr.202356901 -
International Journal of Molecular... Aug 2023Gene expression in eukaryotes begins with transcription in the nucleus, followed by the synthesis of messenger RNA (mRNA), which is then exported to the cytoplasm for... (Review)
Review
Gene expression in eukaryotes begins with transcription in the nucleus, followed by the synthesis of messenger RNA (mRNA), which is then exported to the cytoplasm for its translation into proteins. Along with transcription and translation, mRNA export through the nuclear pore complex (NPC) is an essential regulatory step in eukaryotic gene expression. Multiple factors regulate mRNA export and hence gene expression. Interestingly, proteins from certain types of viruses interact with these factors in infected cells, and such an interaction interferes with the mRNA export of the host cell in favor of viral RNA export. Thus, these viruses hijack the host mRNA nuclear export mechanism, leading to a reduction in host gene expression and the downregulation of immune/antiviral responses. On the other hand, the viral mRNAs successfully evade the host surveillance system and are efficiently exported from the nucleus to the cytoplasm for translation, which enables the continuation of the virus life cycle. Here, we present this review to summarize the mechanisms by which viruses suppress host mRNA nuclear export during infection, as well as the key strategies that viruses use to facilitate their mRNA nuclear export. These studies have revealed new potential antivirals that may be used to inhibit viral mRNA transport and enhance host mRNA nuclear export, thereby promoting host gene expression and immune responses.
Topics: Humans; Active Transport, Cell Nucleus; Virus Diseases; Antiviral Agents; RNA Transport; Eukaryota; RNA, Messenger
PubMed: 37628773
DOI: 10.3390/ijms241612593 -
Cell Reports Mar 2024The cytosolic DNA sensor cyclic GMP-AMP synthase (cGAS) is essential to elicit type I interferon cascade response; thus, the activity of cGAS must be strictly regulated...
The cytosolic DNA sensor cyclic GMP-AMP synthase (cGAS) is essential to elicit type I interferon cascade response; thus, the activity of cGAS must be strictly regulated to boost the antiviral innate immunity. Here, we report that cGAS is responsible for the DNA-induced ISG15 conjugation system. The E3 HERC5 catalyzes the ISGylation of cytoplasmic cGAS at lysine 21, 187, 219, and 458, whereas Ubl carboxy-terminal hydrolase 18 removes the ISGylation of cGAS. The interaction of cGAS and HERC5 depends on the cGAS C-terminal domain and the RRC1-4 and RRC1-5 domains of HERC5. Mechanically, HERC5-catalyzed ISGylation promotes DNA-induced cGAS oligomerization and enhances cGAS enzymatic activity. Deficiency of ISGylation attenuates the downstream inflammatory gene expression induced by the cGAS-STING axis and the antiviral ability in mouse and human cells. Mice deficient in Isg15 or Herc6 are more vulnerable to herpes simplex virus 1 infection. Collectively, our study shows a positive feedback regulation of the cGAS-mediated innate immune pathway by ISGylation.
Topics: Humans; Animals; Mice; Immunity, Innate; Nucleotidyltransferases; DNA; Antiviral Agents; Catalysis; Intracellular Signaling Peptides and Proteins
PubMed: 38421872
DOI: 10.1016/j.celrep.2024.113870 -
Viruses Sep 2023Following virus infections, type I interferons are synthesized to induce the expression of antiviral molecules and interfere with virus replication. The importance of... (Review)
Review
Following virus infections, type I interferons are synthesized to induce the expression of antiviral molecules and interfere with virus replication. The importance of early antiviral type I IFN response against virus invasion has been emphasized during COVID-19 as well as in studies on the microbiome. Further, type I IFNs can directly act on various immune cells to enhance protective host immune responses to viral infections. However, accumulating data indicate that IFN responses can be harmful to the host by instigating inflammatory responses or inducing T cell suppression during virus infections. Also, inhibition of lymphocyte and dendritic cell development can be caused by type I IFN, which is independent of the traditional signal transducer and activator of transcription 1 signaling. Additionally, IFNs were shown to impair airway epithelial cell proliferation, which may affect late-stage lung tissue recovery from the infection. As such, type I IFN-virus interaction research is diverse, including host antiviral innate immune mechanisms in cells, viral strategies of IFN evasion, protective immunity, excessive inflammation, immune suppression, and regulation of tissue repair. In this report, these IFN activities are summarized with an emphasis placed on the functions of type I IFNs recently observed during acute or chronic virus infections.
Topics: Humans; Interferon Type I; COVID-19; Virus Diseases; Antiviral Agents; Virus Replication
PubMed: 37766322
DOI: 10.3390/v15091916