• Journal of Microbiology and Biotechnology
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• v.29 no.12
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• pp.2014-2021
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• 2019

Middle East respiratory syndrome coronavirus (MERS-CoV) belongs to the genus Betacoronavirus and causes severe morbidity and mortality in humans especially when infected patients have underlying diseases such as chronic obstructive pulmonary disease (COPD). Previously, we demonstrated that MERS-CoV-encoded ORF8b strongly inhibits MDA5- and RIG-I-mediated induction of the interferon beta (IFN-β) promoter activities. Here, we report that ORF8b seemed to regulate MDA5 or RIG-I differentially as protein levels of MDA5 were significantly down-regulated while those of RIG-I were largely unperturbed. In addition, ORF8b seemed to efficiently suppress phosphorylation of IRF3 at the residues of 386 and 396 in cells transfected with RIG-I while total endogenous levels of IRF3 remained largely unchanged. Furthermore, ORF8b was able to inhibit all forms of RIG-I; full-length, RIG-I-1-734, and RIG-I-1-228, the last of which contains only the CARD domains. Taken together, it is tempting to postulate that ORF8b may interfere with the CARD-CARD interactions between RIG-I and MAVS. Further detailed analysis is required to delineate the mechanisms of how ORF8b inhibits the MDA5/RIG-I receptor signaling pathway.

• Journal of Microbiology and Biotechnology
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• v.33 no.5
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• pp.600-606
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• 2023

Dengue virus (DENV) is a widespread arbovirus. To efficiently establish infection, DENV evolves multiple strategies to hijack the host innate immune response. Herein, we examined the inhibitory effects of DENV serotype 2 (DENV2) nonstructural proteins on RIG-I-directed antiviral immune response. We found that DENV2 NS2A, NS2B, NS4A, and NS4B significantly inhibited RIG-I-mediated IFN-β promoter activation. The roles of NS2B in RIG-I-directed antiviral immune response are unknown. Our study further showed that NS2B could dose-dependently suppress RIG-I/MAVS-induced activation of IFN-β promoter. Consistently, NS2B significantly decreased RIG-I- and MAVS-induced transcription of IFNB1, ISG15, and ISG56. Mechanistically, NS2B was found to interact with MAVS and IKKε to impair RIG-I-directed antiviral response. Our findings demonstrated a previously uncharacterized function of NS2B in RIG-I-mediated antiviral response, making it a promising drug target for anti-DENV treatments.

• Journal of Microbiology and Biotechnology
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• v.31 no.7
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• pp.942-948
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• 2021

Canine influenza virus (CIV) induces acute respiratory disease in dogs. In this study, we aimed to determine the signaling pathways leading to the induction of IFN-β in a canine respiratory epithelial cell line (KU-CBE) infected with the H3N2 subtype of CIV. Small interfering RNAs (siRNAs) specific to pattern recognition receptors (PRRs) and transcription factors were used to block the IFN-β induction signals in H3N2 CIV-infected KU-CBE cells. Among the PRRs, only the TLR3 and RIG-I expression levels significantly (p < 0.001) increased in CIV-infected cells. Following transfection with siRNA specific to TLR3 (siTLR3) or RIG-I (siRIG-I), the mRNA expression levels of IFN-β significantly (p < 0.001) decreased, and the protein expression of IFN-β also decreased in infected cells. In addition, co-transfection with both siTLR3 and siRIG-I significantly reduced IRF3 (p < 0.001) and IFN-β (p < 0.001) mRNA levels. Moreover, the protein concentration of IFN-β was significantly (p < 0.01) lower in cells co-transfected with both siTLR3 and siRIG-I than in cells transfected with either siTLR3 or siRIG-I alone. Also, the antiviral protein MX1 was only expressed in KU-CBE cells infected with CIV or treated with IFN-β or IFN-α. Thus, we speculate that IFN-β further induces MX1 expression, which might suppress CIV replication. Taken together, these data indicate that TLR3 and RIG-I synergistically induce IFN-β expression via the activation of IRF3, and the produced IFN-β further induces the production of MX1, which would suppress CIV replication in CIV-infected cells.

• Journal of Microbiology and Biotechnology
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• v.28 no.9
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• pp.1554-1562
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• 2018

The type I interferons (IFNs) play a vital role in activation of innate immunity in response to viral infection. Accordingly, viruses have evolved to employ various survival strategies to evade innate immune responses induced by type I IFNs. For example, hepatitis E virus (HEV) encoded papain-like cysteine protease (PCP) has been shown to inhibit IFN activation signaling by suppressing K63-linked de-ubiquitination of retinoic acid-inducible gene I (RIG-I) and TANK-binding kinase 1 (TBK1), thus effectively inhibiting down-stream activation of IFN signaling. In the present study, we demonstrated that HEV inhibits polyinosinic-polycytidylic acid (poly(I:C))-induced $IFN-{\beta}$ transcriptional induction. Moreover, by using reporter assay with individual HEV-encoded gene, we showed that HEV methyltransferase (MeT), a non-structural protein, significantly decreases RIG-I-induced $IFN-{\beta}$ induction and $NF-{\kappa}B$ signaling activities in a dose-dependent manner. Taken together, we report here that MeT, along with PCP, is responsible for the inhibition of RIG-I-induced activation of type I IFNs, expanding the list of HEV-encoded antagonists of the host innate immunity.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.6
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• pp.119-126
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• 2000

In this paper. a simple high-speed crash test rig for members of vehicle was developed for the improvement of crashworthiness of vehicle's side rail. The cart hanging the specimen is accelerated up to 35 mph by the force of freely dropping weight and 1:3 accelerating pulleys. The cart with shock absorbers travels on the rail roads, so it does not transfer any additional vibration to the specimen. To measure the test results, two types of accelerator are considered. the one is a strain gage type and the other is a piezo type. The test rig is rated good to test the specimen like a side rail of vehicle as developing the vehicle's structures in the early design stage.

• Progress in Superconductivity and Cryogenics
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• v.20 no.4
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• pp.31-35
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• 2018

When REBCO coated conductors (CCs) are applied to superconducting devices such as coils and magnets, they are subjected to deformation in various modes such as compression/tension bending, uniaxial/transverse tension and torsion. Despite outstanding performances by REBCO CC tapes, their electromechanical properties have been evaluated primarily under uniaxial tension, therefore data about the critical current ($I_c$) response in the compressive strain region are lacking. In this study, the characteristic responses of $I_c$ in REBCO CC tapes under bending strains in the range from tensile to compressive were evaluated. The springboard bending beam was used, wherein the CC tape sample was soldered onto the surface of the springboard. A Goldacker-type bending test rig, which lacks a support holding the sample during testing, was used as a comparator. Degradation in $I_c$ behaviors, including strain sensitivity, in differently processed REBCO CC tapes were examined based on the test rig used.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1273-1274
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• 2011

• Molecules and Cells
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• v.38 no.9
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• pp.759-764
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• 2015

Tripartite motif protein 25 (TRIM25), mediates K63-linked polyubiquitination of Retinoic acid inducible gene I (RIG-I) that is crucial for downstream antiviral interferon signaling. Here, we demonstrate that TRIM25 is required for melanoma differentiation-associated gene 5 (MDA5) and MAVS mediated activation of NF-${\kappa}B$ and interferon production. TRIM25 is required for the full activation of NF-${\kappa}B$ at the downstream of MAVS, while it is not involved in IRF3 nuclear translocation. Mechanical studies showed that TRIM25 is involved in TRAF6-mediated NF-${\kappa}B$ activation. These collectively indicate that TRIM25 plays an additional role in RIG-I/MDA5 signaling other than RIG-I ubiquitination via activation of NF-${\kappa}B$.

• Journal of Microbiology and Biotechnology
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• v.29 no.10
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• pp.1665-1674
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• 2019

Zika virus (ZIKV) is a mosquito-transmitted, emerging Flavivirus that causes Guillain-$Barr{\acute{e}}$ syndrome and microcephaly in adults and fetuses, respectively. Since ZIKV was first isolated in 1947, severe outbreaks have occurred at various places worldwide, including Yap Island in 2007, French Polynesia in 2013, and Brazil in 2015. Although incidences of ZIKV infection and dissemination have drastically increased, the mechanisms underlying the pathogenesis of ZIKV have not been sufficiently studied. In addition, despite extensive research, the exact roles of individual ZIKV genes in the viral evasion of the host innate immune responses remain elusive. Besides, it is still possible that more than one ZIKV-encoded protein may negatively affect type I interferon (IFN) induction. Hence, in this study, we aimed to determine the modulations of the IFN promoter activity, induced by the MDA5/RIG-I signaling pathway, by over-expressing individual ZIKV genes. Our results show that two nonstructural proteins, NS2A and NS4A, significantly down-regulated the promoter activity of IFN-${\beta}$ by inhibiting multiple signaling molecules involved in the activation of IFN-${\beta}$. Interestingly, while NS2A suppressed both full-length and constitutively active RIG-I, NS4A had inhibitory activity only on full-length RIG-I. In addition, while NS2A inhibited all forms of IRF3 (full-length, regulatory domain-deficient, and constitutively active), NS4A could not inhibit constitutively active IRF3-5D. Taken together, our results showed that NS2A and NS4A play major roles as antagonists of MDA5/RIG-I-mediated IFN-${\beta}$ induction and more importantly, these two viral proteins seem to inhibit induction of the type I IFN responses in differential mechanisms. We believe this study expands our understanding regarding the mechanisms via which ZIKV controls the innate immune responses in cells and may pave the way to development of ZIKV-specific therapeutics.

• Journal of Microbiology and Biotechnology
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• v.30 no.11
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• pp.1651-1658
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• 2020

Since Zika virus (ZIKV) was first detected in Uganda in 1947, serious outbreaks have occurred globally in Yap Island, French Polynesia and Brazil. Even though the number of infections and spread of ZIKV have risen sharply, the pathogenesis and replication mechanisms of ZIKV have not been well studied. ZIKV, a recently highlighted Flavivirus, is a mosquito-borne emerging virus causing microcephaly and the Guillain-Barre syndrome in fetuses and adults, respectively. ZIKV polyprotein consists of three structural proteins named C, prM and E and seven nonstructural proteins named NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5 in an 11-kb single-stranded positive sense RNA genome. The function of individual ZIKV genes on the host innate immune response has barely been studied. In this study, we investigated the modulations of the NF-κB promoter activity induced by the MDA5/RIG-I signaling pathway. According to our results, two nonstructural proteins, NS2A and NS4A, dramatically suppressed the NF-κB promoter activity by inhibiting signaling factors involved in the MDA5/RIG-I signaling pathway. Interestingly, NS2A suppressed all components of MDA5/RIG-I signaling pathway, but NS4A inhibited most signaling molecules, except IKKε and IRF3-5D. In addition, both NS2A and NS4A downregulated MDA5-induced NF-κB promoter activity in a dosedependent manner. Taken together, our results suggest that NS2A and NS4A signifcantly antagonize MDA5/RIG-I-mediated NF-κB production, and these proteins seem to be controlled by different mechanisms. This study could help understand the mechanisms of how ZIKV controls innate immune responses and may also assist in the development of ZIKV-specific therapeutics.