• The Journal of Korea Robotics Society
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• v.17 no.2
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• pp.159-163
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• 2022

A linearly moving structure in the area where the friction force is dominant - such as ducts filled with grease in the nuclear power plant - experiences increase in friction since the contact surface gets larger as the structure proceeds. To solve this problem is critical for the pipe inspection robot to investigate further area and this makes the system more energy-efficient. In this paper, we propose a passively growing sheath that can be added to linearly moving structures using zipper mechanism. The mechanism enables the linearly moving structures to maintain rolling contact condition against external environment, which provides substantial reduction in kinetic friction. To analyze the effect of the mechanism's head shape, we establish a physical model and compare to the experimental results. Finally, we have shown that the passively growing sheath can be successfully applied to the pipe inspection robot for the nuclear power plant.

• Journal of Life Science
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• v.30 no.11
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• pp.1012-1020
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• 2020

Remicade is a therapeutic biosimilar natural antibody in which the mouse variable domain has been linked to the human constant domain. It is a chimeric monoclonal antibody specific to tumor necrosis factor-alpha (TNF-α) and has been developed for the treatment of rheumatoid arthritis. To investigate the biological activity of the Remicade antibody, we carried out a bioinformatics study using a protein data bank to characterize the TNF-α antigen binding mechanism of the Remicade natural antibody. Because the production of the Remicade antibody is often limited by genetic instability of the natural antibody-producing cell, we generated a Remicade single-chain variable domain fragment antibody (Remicade) in which a heavy chain variable domain (VH) is joined with a light chain variable domain (VL) by a polypeptide linker. Furthermore, Remicade was fused to a leucine zipper (RemicadeScZip) for higher production and higher antigen-binding activity than Remicade. The Remicade and Remicade ScZip were expressed in Escherichia coli and purified by a Ni⁺-NTA-agarose column. As expected, the purified proteins had migrated as 28.80 kDa and 33.96 kDa in sodium dodecyl sulfate-polyacrylamide electrophoresis. The TNF-α antigen binding activity of Remicade was not observed by ELISA and western blot. In contrast, RemicadeScZip showed antigen-binding activity. Additional bio-layer interferometry analysis confirmed the antigen-binding activity of RemicadeScZip, suggesting that the leucine zipper stabilized the folding of RemicadeScZip in a denatured condition and improved the TNF-α antigenbinding activity.

• BMB Reports
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• v.37 no.2
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• pp.139-143
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• 2004

The antioxidant responsive element (ARE) is a cis-acting regulatory element of genes encoding phase II detoxification enzymes and antioxidant proteins, such as NAD(P)H: quinone oxidoreductase 1, glutathione S-transferases, and glutamate-cysteine ligase. Interestingly, it has been reported that Nrf2 (NF-E2-related factor 2) regulates a wide array of ARE-driven genes in various cell types. Nrf2 is a basic leucine zipper transcription factor, which was originally identified as a binding protein of locus control region of ss-globin gene. The DNA binding sequence of Nrf2 and ARE sequence are very similar, and many studies demonstrated that Nrf2 binds to the ARE sites leading to up-regulation of downstream genes. The function of Nrf2 and its downstream target genes suggests that the Nrf2-ARE pathway is important in the cellular antioxidant defense system. In support of this, many studies showed a critical role of Nrf2 in cellular protection and anti-carcinogenicity, implying that the Nrf2-ARE pathway may serve as a therapeutic target for neurodegenerative diseases and cancers, in which oxidative stress is closely implicated.

• Journal of Microbiology
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• v.45 no.3
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• pp.193-198
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• 2007

A marine bacterium was isolated from Mai Po Nature Reserve of Hong Kong and identified as Vibrio cholerae MP-1. It contains a small plasmid designated as pVC of 3.8 kb. Four open reading frames (ORFs) are identified on the plasmid, but none of them shows homology to any known protein. Database search indicated that a 440 bp fragment is 96% identical to a fragment found in a small plasmid of another V. cholerae. Further experiments demonstrated that a 2.3 kb EcoRI fragment containing the complete ORF1, partial ORF4 and their intergenic region could self-replicate. Additional analyses revealed that sequence upstream of ORF1 showed the features characteristic of theta type replicons. Protein encoded by ORF1 has two characteristic motifs existed in most replication initiator proteins (Rep): the leucine zipper (LZ) motif located at the N-terminal region and the alpha helix-turn-alpha helix motif (HTH) located at the C-terminal end. The results suggest that pVC replicates via the theta type mechanism and is likely a novel type of theta replicon.

• Molecules and Cells
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• v.44 no.5
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• pp.342-355
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• 2021

The microphthalmia-associated transcription factor family (MiT family) proteins are evolutionarily conserved transcription factors that perform many essential biological functions. In mammals, the MiT family consists of MITF (microphthalmia-associated transcription factor or melanocyte-inducing transcription factor), TFEB (transcription factor EB), TFE3 (transcription factor E3), and TFEC (transcription factor EC). These transcriptional factors belong to the basic helix-loop-helix-leucine zipper (bHLH-LZ) transcription factor family and bind the E-box DNA motifs in the promoter regions of target genes to enhance transcription. The best studied functions of MiT proteins include lysosome biogenesis and autophagy induction. In addition, they modulate cellular metabolism, mitochondria dynamics, and various stress responses. The control of nuclear localization via phosphorylation and dephosphorylation serves as the primary regulatory mechanism for MiT family proteins, and several kinases and phosphatases have been identified to directly determine the transcriptional activities of MiT proteins. In different immune cell types, each MiT family member is shown to play distinct or redundant roles and we expect that there is far more to learn about their functions and regulatory mechanisms in host defense and inflammatory responses.

• BMB Reports
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• v.51 no.8
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• pp.388-393
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• 2018

The activating transcription factor (ATF) 4 belongs to the ATF/CREB (cAMP Response Element Binding bZIP [Basic Leucine Zipper]) transcription factor family, and plays a central role in the UPR (Unfolded Protein Response) process in cells. The induction of ATF4 expression has previously been shown to increase the replication of HIV-1. However, the detailed mechanism underlying this effect and the factors involved in the regulation of ATF4 function are still unknown. Here, we demonstrate first that knocking out ATF4 using siRNA shows a strong negative effect on HIV-1 production, indicating that ATF4 is a functional positive cellular factor in HIV-1 production. To determine the mechanism by which ATF4 regulates the HIV-1 life cycle, we assessed the effect of the overexpression of wild type ATF4 and its various derivatives on HIV-1 LTR-mediated transcriptional activation and the production of HIV-1 particles. This effect was studied through co-transfection experiments with either reporter vectors or proviral DNA. We found that the N-terminal domains of ATF4 are involved in HIV-1 LTR-mediated transcriptional activation, and thus in HIV-1 production.

• Journal of Life Science
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• v.32 no.3
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• pp.241-248
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• 2022

NF-κB acts as a critical transcription factor in inflammation and innate immunity, and it is also closely involved in cell survival and tumorigenesis via induction of anti-apoptotic genes. In these processes, NF-κB cooperates with multiple other signaling molecules and pathways, and although many studies have demonstrated that Hsp90 regulates NF-κB activity, the exact mechanism is unclear. In this study, we investigated the relationship between Hsp90 and IKKγ in the regulation of NF-κB using expression plasmids of IKK complex components. Wild-type and deletion mutants of IKKγ were expressed together with Hsp90, and the combined regulatory effect of Hsp90 and IKKγ on NF-κB activation was assayed. The results show that Hsp90 activates NF-κB by promoting the phosphorylation and degradation of IκBα and that activation of NF-κB by NIK and LPS was increased by Hsp90. IKKγ elevated the effect of Hsp90 on NF-κB activation by increasing phosphorylation and degradation of IκBα. The positive regulation on NF-κB by Hsp90 and IKKγ was also proved in analysis with IKKβ-EE, the constitutively active form of IKKβ. In experiments with the deletion mutants of IKKγ, the N-terminal IKKβ binding domain, C-terminal leucine zipper, and zinc finger domains of IKKγ were found not necessary for the positive regulation of NF-κB activity. Additionally, the expression of pro-inflammatory cytokines was synergistically elevated by Hsp90 and IKKγ. These results indicate that inhibiting the interaction between Hsp90 and IKKγ is a possible strategic method for controlling NF-κB and related diseases.

• 한국균학회소식:학술대회논문집
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• 2016.05a
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• pp.27-27
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• 2016

The ascomycete fungus Fusarium graminearum is the most common pathogen of Fusarium head blight (FHB), a devastating disease for major cereal crops worldwide. FHB causes significant crop losses by reducing grain yield and quality as well as contaminating cereals with trichothecenes and zearalenone (ZEA) that pose a serious threat to animal health and food safety. ZEA is a causative agent of hyperestrogenic syndrome in mammals and can result in reproductive disorders in farm animals. In F. graminearum, the ZEA biosynthetic cluster is composed of four genes, PKS4, PKS13, ZEB1, and ZEB2, which encode a reducing polyketide synthase, a nonreducing polyketide synthase, an isoamyl alcohol oxidase, and a transcription factor, respectively. Although it is known that ZEB2 primarily acts as a regulator of ZEA biosynthetic cluster genes, the mechanism underlying this regulation remains undetermined. In this study, two isoforms (ZEB2L and ZEB2S) from the ZEB2 gene in F. graminearum were characterized. It was revealed that ZEB2L contains a basic leucine zipper (bZIP) DNA-binding domain at the N-terminus, whereas ZEB2S is an N-terminally truncated form of ZEB2L that lacks the bZIP domain. Interestingly, ZEA triggered the induction of both ZEB2L and ZEB2S transcription. In ZEA producing condition, the expression of ZEB2S transcripts via alternative promoter usage was directly or indirectly initiated by ZEA. Physical interaction between ZEB2L and ZEB2L as well as between ZEB2L and ZEB2S was observed in the nucleus. The ZEB2S-ZEB2S interaction was detected in both the cytosol and the nucleus. ZEB2L-ZEB2L oligomers activated ZEA biosynthetic cluster genes, including ZEB2L. ZEB2S inhibited ZEB2L transcription by forming ZEB2L-ZEB2S heterodimers, which reduced the DNA-binding activity of ZEB2L. This study provides insight into the autoregulation of ZEB2 expression by alternative promoter usage and a feedback loop during ZEA production.

• Journal of Life Science
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• v.17 no.7 s.87
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• pp.889-895
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• 2007

A conventional kinesin, KIF5/kinesin-I, is composed of two kinesin heavy chains (KHCs) and two kinesin light chains (KLCs) and binds directly to microtubules. KIF5 motor mediates the transport of various membranous organelles, but the mechanism how they recognize and bind to a specific cargo has not yet been completely elucidated. Here, we used the yeast two-hybrid system to identify the neuronal protein(s) that interacts with the tetratricopeptide repeats (TRP) of KLCI and found a specific interaction with JNK/stress-activated protein kinase-associated protein 1 (JSAP1/JIPP3). The yeast two-hybrid assay demonstrated that the TRP 1,2 domain-containing region of KLCI mediated binding to the leucine zipper domain of JSAP1. JSAP1 also bound to the TRP region of lac2 but not to neuronal KIF5A, KIF5C and ubiquitous KIF5B in the yeast two-hybrid assay. In addition, these proteins showed specific interactions in the GST pull-down assay and by co-immunoprecipitation. KLCI and KIF5B interacted with GST-ISAP1 fusion proteins, but not with GST alone. An antibody to JSAPI specifically co-immunoprecipitated KIF5s associated with JSAP1 from mouse brain extracts. These results suggest that JSAP1, as KLC1 receptor, is involved in the KIF5 mediated transport.

• Journal of Life Science
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• v.26 no.9
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• pp.991-998
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• 2016

NF-κB acts as a critical transcription factor for the survival of cells via the induction of antiapoptotic genes. Constitutive activation of NF-κB in many types of solid tumors suggests that the inhibition of NF-κB might prevent or inhibit tumorigenesis. Although a number of studies demonstrated that Hsp70 regulated NF-κB activity, the exact mechanism is not clear. This study investigated the functional relationship of Hsp70 and IKKγ in the regulation of NF-κB activation using expression plasmids of components of the IKK complex. Wild-type and deletion mutants of IKKγ were expressed together with Hsp70, and the combined regulatory effect of Hsp70 and IKKγ on NF-κB activation was assayed. Hsp70 suppressed the activation of NF-κB in a reporter plasmid assay. Hsp70 also suppressed the phosphorylation and degradation of IκBα. The suppressive effect of Hsp70 on NF-κB activation was synergistically elevated by IKKγ. The N-terminal IKKβ binding site, C-terminal leucine zipper, and zinc finger domains of IKKγ were not necessary for the suppressive effect. Furthermore, Hsp70 and IKKγ synergistically suppressed the induction of COX-2 expression by lipopolysaccharides in RAW264.7 cells. These results suggest that overexpression of Hsp70 and IKKγ may be a strategic method for inhibition of NF-κB and related diseases.