• BMB Reports
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• v.48 no.12
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• pp.696-701
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• 2015

Toll-like receptor 3 (TLR3) recognizes viral double-stranded RNA. It stimulates pro-inflammatory cytokine and interferon production. Here we reported the expression of a novel isoform of TLR3 in human astrocyte cell lines whose message is generated by alternative splicing. The isoform represents the N-terminus of the protein. It lacks many of the leucine-rich repeat domains, the transmembrane domain, and the intracellular Toll/interleukin-1 receptor domain of TLR3. Type I interferons (interferon-α and interferon-β) induced the expression of this isoform. Exogenous overexpression of this isoform inhibited interferon regulatory factor 3, signal transducers and activators of transcription 1, and Inhibitor of kappa B α signaling following stimulation. This isoform of TLR3 also inhibited the production of chemokine interferon-γ-inducible protein 10. Our study clearly demonstrated that the expression of this isoform of TLR3 was a negative regulator of signaling pathways and that it was inducible by type I interferons. We also found that this isoform could modulate inflammation in the brain.

• Journal of Animal Science and Technology
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• v.65 no.1
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• pp.183-196
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• 2023

Interferon-alpha inducible protein 6 (IFI6) is an interferon-stimulated gene (ISG), belonging to the FAM14 family of proteins and is localized in the mitochondrial membrane, where it plays a role in apoptosis. Transcriptional regulation of this gene is poorly understood in the context of inflammation by intracellular nucleic acid-sensing receptors and pathological conditions caused by viral infection. In this study, chicken IFI6 (chIFI6) was identified and studied for its molecular features and transcriptional regulation in chicken cells and tissues, i.e., lungs, spleens, and tracheas from highly pathogenic avian influenza virus (HPAIV)-infected chickens. The chIFI6-coding sequences contained 1638 nucleotides encoding 107 amino acids in three exons, whereas the duck IFI6-coding sequences contained 495 nucleotides encoding 107 amino acids. IFI6 proteins from chickens, ducks, and quail contain an IF6/IF27-like superfamily domain. Expression of chIFI6 was higher in HPAIV-infected White Leghorn chicken lungs, spleens, and tracheas than in mock-infected controls. TLR3 signals regulate the transcription of chIFI6 in chicken DF-1 cells via the NF-κB and JNK signaling pathways, indicating that multiple signaling pathways differentially contribute to the transcription of chIFI6. Further research is needed to unravel the molecular mechanisms underlying IFI6 transcription, as well as the involvement of chIFI6 in the pathogenesis of HPAIV in chickens.

• Molecules and Cells
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• v.28 no.4
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• pp.365-368
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• 2009

Toll-like receptors (TLRs) play an important role in host defense by sensing invading microbial pathogens and initiating innate immune responses. The stimulation of TLRs by microbial components triggers the activation of myeloid differential factor 88 (MyD88)- and toll-interleukin-1 receptor domain-containing adapter inducing interferon-${\beta}$ (TRIF)-dependent downstream signaling pathways. Isoliquiritigenin (ILG), an active ingredient of Licorice, has been used for centuries to treat many chronic diseases. ILG inhibits the MyD88-dependent pathway by inhibiting the activity of inhibitor-${\kappa}B$ kinase. However, it is not known whether ILG inhibits the TRIF-dependent pathway. To evaluate the therapeutic potential of ILG, we examined its effect on signal transduction via the TRIF-dependent pathway of TLRs induced by several agonists. ILG inhibited nuclear factor-${\kappa}B$ and interferon regulatory factor 3 activation induced by lipopolysaccharide or polyinosinic-polycytidylic acid. ILG inhibited the lipopolysaccharide-induced phosphorylation of interferon regulatory factor 3 as well as interferon-inducible genes such as interferon inducible protein-10, and regulated activation of normal T-cell expressed and secreted (RANTES). These results suggest that ILG can modulate TRIF-dependent signaling pathways of TLRs, leading to decreased inflammatory gene expression.

• IMMUNE NETWORK
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• v.16 no.4
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• pp.249-255
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• 2016

Exogenous nucleic acids induce an innate immune response in mammalian host cells through activation of the retinoic acid-inducible gene I (RIG-I). We evaluated RIG-I protein for RNA binding and ATPase stimulation with RNA ligands to investigate the correlation with the extent of immune response through RIG-I activation in cells. RIG-I protein favored blunt-ended, double-stranded RNA (dsRNA) ligands over sticky-ended dsRNA. Moreover, the presence of the 5'-triphosphate (5'-ppp) moiety in dsRNA further enhanced binding affinity to RIG-I. Two structural motifs in RNA, blunt ends in dsRNA and 5'-ppp, stimulated the ATP hydrolysis activity of RIG-I. These structural motifs also strongly induced IFN expression as an innate immune response in cells. Therefore, we suggest that IFN induction through RIG-I activation is mainly determined by structural motifs in dsRNA that increase its affinity for RIG-I protein and stimulate ATPase activity in RIG-I.

• Journal of Microbiology and Biotechnology
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• v.28 no.11
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• pp.1908-1915
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• 2018

Upon viral infection, the host cell recognizes the invasion through a number of pattern recognition receptors. Melanoma differentiation associated gene 5 (MDA5) and retinoic acid-inducible gene-I (RIG-I) recognize RNA molecules derived from invading viruses, activating down-stream signaling cascades, culminating in the induction of the type I interferon. On the other hand, viruses have evolved to evade type I interferon-mediated inhibition. Hepatitis E virus has been shown to encode a few antagonists of type I interferon and it is not surprising that viruses encode multiple mechanisms of viral evasion. In the present study, we demonstrated that HEV PCP strongly down-regulates MDA5-mediated activation of interferon ${\beta}$ induction in a dose-dependent manner. Interestingly, MDA5 protein expression was almost completely abolished. In addition, polyinosinic polycytidylic acid (poly(I:C))- and Sendai virus-mediated activation of type I interferon responses were similarly abrogated in the presence of HEV PCP. Furthermore, HEV PCP down-regulates several molecules that play critical roles in the induction of type I IFN expression. Taken together, these data collectively suggest that HEV-encoded PCP is a strong antagonist of type I interferon.

• Animal Bioscience
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• v.37 no.8
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• pp.1377-1386
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• 2024

Objective: Embryonic interferon-tau (IFNT) and progesterone affect expression of interferon-stimulated genes (ISGs), progesterone receptor (PGR) and progesterone-induced blocking factor (PIBF) in the ovine thyroid. Methods: Thyroids of ewes were sampled at day 16 of nonpregnancy, days 13, 16, and 25 of pregnancy, and real-time quantitative polymerase chain reaction assay, western blot and immunohistochemistry were used to detect expression of ISGs, PGR, and PIBF. Results: Free ISG15 protein was undetected, but ISG15 conjugated proteins upregulated at day 16 of pregnancy, and expression levels of ISG15 conjugated proteins, PGR isoform (70 kDa), PIBF, interferon-gamma-inducible protein 10 and myxovirusresistance protein 1 peaked, but expression level of signal transducer and activator of transcription 1 was the lowest at day 16 of pregnancy. In addition, the expression levels of PGR isoform (70 kDa) and signal transducer and activator of transcription 1 (STAT1) decreased, but levels of PGR isoform (43 kDa), 2',5'-oligoadenylate synthetase, IP-10 and MX1 increased at day 25 of pregnancy comparing with day 16 of the estrous cycle. Conclusion: Early pregnancy affects expression of ISGs, PGR, and PIBF in maternal thyroid through IFNT and progesterone, which may regulate thyroid autoimmunity and thyroid hormone secretion in ewes.

• Molecular & Cellular Toxicology
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• v.5 no.3
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• pp.187-192
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• 2009

Toll-like receptors (TLRs) play an important role in host defense by sensing invading microbial pathogens. The stimulation of TLRs by microbial components triggers the activation of the myeloid differential factor 88 (MyD88)- and toll-interleukin-1 receptor domain-containing adapter inducing interferon-$\beta$ (TRIF)-dependent downstream signaling pathways. TLR/MyD88 signaling pathway induces the activation of nuclear factor-kappa B (NF-${\kappa}B$) and the expression of inflammatory cytokine genes, including tumor necrosis factor-alpha, interleukin (IL)-6, IL-12, and IL-$1{\beta}$. On the other hand, TLR/TRIF signaling pathway induces the delayed-activation of NF-${\kappa}B$ and interferon regulatory factor 3 (IRF3), and the expression of type I interferons (IFNs) and IFN-inducible genes. The divalent heavy metal cadmium (Cd) is clearly toxic to most mammalian organ systems, especially the immune system. Yet, the underlying toxic mechanism(s) remain unclear. Cd inhibits the MyD88-dependent pathway by ceasing the activity of inhibitor-${\kappa}B$ kinase. However, it is not known whether Cd inhibits the TRIF-dependent pathway. Presently, Cd inhibited NF-${\kappa}B$ and IRF3 activation induced by lipopolysaccharide (LPS) and polyinosinic-polycytidylic acid. Cd inhibited LPS-induced IRF3 phosphorylation and IFN-inducible genes such as interferon inducible protein-10 and regulated on activation normal T-cell expressed and secreted (RANTES). These results suggest that Cd can modulate TRIF-dependent signaling pathways of TLRs.

• Genomics & Informatics
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• v.11 no.1
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• pp.15-23
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• 2013

CD8+T cells are key factors mediating hepatitis B virus (HBV) clearance. However, these cells are killed through HBV-induced apoptosis during the antigen-presenting period in HBV-induced chronic liver disease (CLD) patients. Interferon-inducible protein 6 (IFI6) delays type I interferon-induced apoptosis in cells. We hypothesized that single nucleotide polymorphisms (SNPs) in the IFI6 could affect the chronicity of CLD. The present study included a discovery stage, in which 195 CLD patients, including chronic hepatitis B (HEP) and cirrhosis patients and 107 spontaneous recovery (SR) controls, were analyzed. The genotype distributions of rs2808426 (C > T) and rs10902662 (C > T) were significantly different between the SR and HEP groups (odds ratio [OR], 6.60; 95% confidence interval [CI], 1.64 to 26.52, p = 0.008 for both SNPs) and between the SR and CLD groups (OR, 4.38; 95% CI, 1.25 to 15.26; p = 0.021 and OR, 4.12; 95% CI, 1.18 to 14.44; p = 0.027, respectively). The distribution of diplotypes that contained these SNPs was significantly different between the SR and HEP groups (OR, 6.58; 95% CI, 1.63 to 25.59; p = 0.008 and OR, 0.15; 95% CI, 0.04 to 0.61; p = 0.008, respectively) and between the SR and CLD groups (OR, 4.38; 95% CI, 1.25 to 15.26; p = 0.021 and OR, 4.12; 95% CI, 1.18 to 14.44; p = 0.027, respectively). We were unable to replicate the association shown by secondary enrolled samples. A large-scale validation study should be performed to confirm the association between IFI6 and HBV clearance.

• BMB Reports
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• v.52 no.2
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• pp.133-138
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• 2019

Upon viral infection, the 2', 5'-oligoadenylate synthetase (OAS)-ribonuclease L (RNaseL) system works to cleave viral RNA, thereby blocking viral replication. However, it is unclear whether OAS proteins have a role in regulating gene expression. Here, we show that OAS1 and OAS3 act as negative regulators of the expression of chemokines and interferon-responsive genes in human macrophages. Clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein-9 nuclease (Cas9) technology was used to engineer human myeloid cell lines in which the OAS1 or OAS3 gene was deleted. Neither OAS1 nor OAS3 was exclusively responsible for the degradation of rRNA in macrophages stimulated with poly(I:C), a synthetic surrogate for viral double-stranded (ds)RNA. An mRNA sequencing analysis revealed that genes related to type I interferon signaling and chemokine activity were increased in $OAS1^{-/-}$ and $OAS3^{-/-}$ macrophages treated with intracellular poly(I:C). Indeed, retinoic-acid-inducible gene (RIG)-I- and interferon-induced helicase C domain-containing protein (IFIH1 or MDA5)-mediated induction of chemokines and interferon-stimulated genes was regulated by OAS3, but Toll-like receptor 3 (TLR3)- and TLR4-mediated induction of those genes was modulated by OAS1 in macrophages. However, stimulation of these cells with type I interferons had no effect on OAS1- or OAS3-mediated chemokine secretion. These data suggest that OAS1 and OAS3 negatively regulate the expression of chemokines and interferon-responsive genes in human macrophages.

• Journal of Life Science
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• v.25 no.1
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• pp.84-92
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• 2015

Interferon inducible transmembrane protein (IFITM) family genes have been implicated in various cellular processes such as the homotypic cell adhesion functions of IFNs and cellular anti-proliferative activities. The present study aimed to investigate whether the polymorphisms of the IFITM2 and IFITM5 genes are associated with susceptibility to UC. We identified a total of thirteen polymorphisms (eleven SNPs and two variations) in the IFITM2 gene and twelve polymorphisms (eleven SNPs and one variation) in the IFITM5 gene, by the direct sequencing method. Genotype analysis in the IFITM2 and IFITM5 SNPs was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and Taq-Man probe analysis, and the haplotype frequencies of IFITM2 and IFITM5 SNPs for multiple loci were estimated using the expectation maximization (EM) algorithm. The genotype and allele frequencies of IFITM2 SNPs, as well as IFITM5 SNPs, in UC patients were not significantly different from those of the healthy controls. We also analyzed the combined frequencies of rs77537847 of IFITM1, rs909097 of IFITM2, and rs56069858 of IFITM5 in the UC patients and the healthy controls. Although the distribution of the major combined genotype frequency did not differ significantly between the healthy controls and the UC patients, the GGT combined frequency in the healthy controls was significantly different from that in the UC patients (P=0.002). This result suggests that the combined genotype of the IFITMs polymorphisms may be associated with a susceptibility to UC and could be a useful genetic marker for UC.