• BMB Reports
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• v.47 no.10
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• pp.546-551
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• 2014

The insecticidal activity of Bacillus thuringiensis (Bt) Cry toxins involves toxin stabilization, oligomerization, passage across the peritrophic membrane (PM), binding to midgut receptors and pore-formation. The residues Arg-158 and Tyr-170 have been shown to be crucial for the toxicity of Bt Cry4Ba. We characterized the biological function of these residues. In mosquito larvae, the mutants R158A/E/Q (R158) could hardly penetrate the PM due to a significantly reduced ability to alter PM permeability; the mutant Y170A, however, could pass through the PM, but degraded in the space between the PM and the midgut epithelium. Further characterization by oligomerization demonstrated that Arg-158 mutants failed to form correctly sized high-molecular weight oligomers. This is the first report that Arg-158 plays a role in the formation of Cry4Ba oligomers, which are essential for toxin passage across the PM. Tyr-170, meanwhile, is involved in toxin stabilization in the toxic mechanism of Cry4Ba in mosquito larvae.

• Parasites, Hosts and Diseases
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• v.54 no.6
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• pp.711-717
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• 2016

Toxoplasma gondii is an obligate intracellular parasite that stimulates production of high levels of proinflammatory cytokines, which are important for innate immunity. NLRs, i.e., nucleotide-binding oligomerization domain (NOD)-like receptors, play a crucial role as innate immune sensors and form multiprotein complexes called inflammasomes, which mediate caspase-1-dependent processing of $pro-IL-1{\beta}$. To elucidate the role of inflammasome components in T. gondiiinfected THP-1 macrophages, we examined inflammasome-related gene expression and mechanisms of inflammasome-regulated cytokine $IL-1{\beta}$ secretion. The results revealed a significant upregulation of $IL-1{\beta}$ after T. gondii infection. T. gondii infection also upregulated the expression of inflammasome sensors, including NLRP1, NLRP3, NLRC4, NLRP6, NLRP8, NLRP13, AIM2, and NAIP, in a time-dependent manner. The infection also upregulated inflammasome adaptor protein ASC and caspase-1 mRNA levels. From this study, we newly found that T. gondii infection regulates NLRC4, NLRP6, NLRP8, NLRP13, AIM2, and neuronal apoptosis inhibitor protein (NAIP) gene expressions in THP-1 macrophages and that the role of the inflammasome-related genes may be critical for mediating the innate immune responses to T. gondii infection.

• Applied Microscopy
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• v.35 no.4
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• pp.16-23
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• 2005

Peroxiredoxins (Prxs) are a superfamily of thiol-specific antioxidant proteins present in all organism and involved in the hydroperoxide detoxification of the cell. To determine the structural organization of yeast-Prx, electron microscopic analysis was performed. The average images of yeast-Prxs revealed three different structure, i.e. spherical-shaped structure, ring-shaped structure and irregularly-shaped small particles. In order to analyze the conformational change of yeast-Prx by reduction and oxidation, Prxs were subjected to DTT and $H_2O_2$. In presence of DTT, yeast-Prx showed a high tendency to form a decamer. However, they changed into dimeric or spherical structure in the oxidized state. Here we also show ionic interaction between dimeric subunits is primarily responsible for yeast-Prx oligomerization.

• Clinical and Experimental Pediatrics
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• v.59 no.sup1
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• pp.5-9
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• 2016

Blau syndrome (BS) is a rare autosomal dominant, inflammatory syndrome that is characterized by the clinical triad of granulomatous dermatitis, symmetric arthritis, and recurrent uveitis. Mutations in the nucleotide oligomerization domain 2 (NOD2 ) gene are responsible for causing BS. To date, up to 30 Blau-associated genetic mutations have been identified within this gene. We report a novel NOD2 genetic mutation that causes BS. A girl, aged 8 years, and her brother, aged 10 years, developed erythematous skin rashes and uveitis. The computed tomography angiogram of the younger sister showed features of midaortic dysplastic syndrome. The brother had more prominent joint involvement than the sister. Their father (38 years) was also affected by uveitis; however, only minimal skin involvement was observed in his case. The paternal aunt (39 years) and her daughter (13 years) were previously diagnosed with sarcoidosis. Mutational analysis revealed a novel c.1439 A>G mutation in the NOD2 gene in both siblings. The novel c.1439 A>G mutation in the NOD2 gene was found in a familial case of BS. Although BS is rare, it should always be considered in patients presenting with sarcoidosis-like features at a young age. Early diagnosis of BS and prompt multisystem workup including the eyes and joints can improve the patient's outcome.

• BMB Reports
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• v.52 no.11
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• pp.665-670
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• 2019

Nucleotide-binding oligomerization domain protein 2 (NOD2), an intracellular pattern recognition receptor, plays important roles in inflammation and cell death. Previously, we have shown that NOD2 is expressed in vascular smooth muscle cells (VSMCs) and that NOD2 deficiency promotes VSMC proliferation, migration, and neointimal formation after vascular injury. However, its role in endoplasmic reticulum (ER) stress-induced cell death in VSMCs remains unclear. Thus, the objective of this study was to evaluate ER stress-induced viability of mouse primary VSMCs. NOD2 deficiency increased ER stress-induced cell death and expression levels of apoptosis mediators (cleaved caspase-3, Bax, and Bak) in VSMCs in the presence of tunicamycin (TM), an ER stress inducer. In contrast, ER stress-induced cell death and expression levels of apoptosis mediators (cleaved caspase-3, Bax, and Bak) were decreased in NOD2-overexpressed VSMCs. We found that the $IRE-1{\alpha}-XBP1$ pathway, one of unfolded protein response branches, was decreased in NOD2-deficient VSMCs and reversed in NOD2-overexpressed VSMCs in the presence of TM. Furthermore, NOD2 deficiency reduced the expression of XBP1 target genes such as GRP78, PDI-1, and Herpud1, thus improving cell survival. Taken together, these data suggest that the induction of ER stress through NOD2 expression can protect against TM-induced cell death in VSMCs. These results may contribute to a new paradigm in vascular homeostasis.

• Molecules and Cells
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• v.44 no.10
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• pp.758-769
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• 2021

Calcium homeostasis modulator 1 (CALHM1) is a membrane protein with four transmembrane helices that form an octameric ion channel with voltage-dependent activation. There are four conserved cysteine (Cys) residues in the extracellular domain that form two intramolecular disulfide bonds. We investigated the roles of C42-C127 and C44-C161 in human CALHM1 channel biogenesis and the ionic current (I_CALHM1). Replacing Cys with Ser or Ala abolished the membrane trafficking as well as I_CALHM1. Immunoblotting analysis revealed dithiothreitol-sensitive multimeric CALHM1, which was markedly reduced in C44S and C161S, but preserved in C42S and C127S. The mixed expression of C42S and wild-type did not show a dominant-negative effect. While the heteromeric assembly of CALHM1 and CALHM3 formed active ion channels, the co-expression of C42S and CALHM3 did not produce functional channels. Despite the critical structural role of the extracellular cysteine residues, a treatment with the membrane-impermeable reducing agent tris(2-carboxyethyl) phosphine (TCEP, 2 mM) did not affect I_CALHM1 for up to 30 min. Interestingly, incubation with TCEP (2 mM) for 2-6 h reduced both I_CALHM1 and the surface expression of CALHM1 in a time-dependent manner. We propose that the intramolecular disulfide bonds are essential for folding, oligomerization, trafficking and maintenance of CALHM1 in the plasma membrane, but dispensable for the voltage-dependent activation once expressed on the plasma membrane.

• Biomolecules & Therapeutics
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• v.29 no.4
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• pp.410-418
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• 2021

Helicobacter pylori causes chronic gastritis through cag pathogenicity island (cagPAI), vacuolating cytotoxin A (VacA), lipopolysaccharides (LPS), and flagellin as pathogen-related molecular patterns (PAMPs), which, in combination with the pattern recognition receptors (PRRs) of host cells promotes the expression and secretion of inflammation-causing cytokines and activates innate immune responses such as inflammasomes. To identify useful compounds against H. pylori-associated gastric disorders, the effect of chalcone derivatives to activate the nucleotide-binding oligomerization domain (NOD)-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome was examined in an H. pylori-infected human monocytic THP-1 cell line in this study. Among the five synthetic structurally-related chalcone derivatives examined, 2'-hydroxy-4',6'-dimethoxychalcone (8) and 2'-hydroxy-3,4,5-trimethoxychalcone (12) strongly blocked the NLRP3 inflammasome in H. pylori-infected THP-1 cells. At 10 μM, these compounds inhibited the production of active IL-1β, IL-18, and caspase-1, and apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) oligomerization, but did not affect the expression levels of NLRP3, ASC, and pro-caspase-1. The interruption of NLRP3 inflammasome activation by these compounds was found to be mediated via the inhibition of the interleukin-1 receptor-associated kinase 4 (IRAK4)/IκBα/NF-κB signaling pathway. These compounds also inhibited caspase-4 production associated with non-canonical NLRP3 inflammasome activation. These results show for the first time that certain chalcones could interrupt the activation of the NLRP3 inflammasome in H. pylori-infected THP-1 cells. Therefore, these chalcones may be helpful in alleviating H. pylori-related inflammatory disorders including chronic gastritis.

• Pediatric Infection and Vaccine
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• v.29 no.3
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• pp.166-172
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• 2022

Blau syndrome is a systemic autoinflammatory disease presenting with non-caseating granulomatous dermatitis, chronic uveitis, and arthritis. It is caused by a gain-of-function variant of the nucleotide-binding oligomerization domain protein 2 gene, which leads to the overactivation of inflammatory cytokines and eventually causes autoinflammation. Since the symptoms of Blau syndrome are nonspecific and usually do not appear simultaneously, it is challenging to differentiate Blau syndrome from other inflammatory disorders. This is a case report of a 13-month-old boy who had suffered from recurrent skin rash and fever. The patient was previously misdiagnosed as refractory Kawasaki disease twice and was treated with intravenous immunoglobulin and systemic glucocorticoid, which only resulted in transient improvement of the symptoms. He was eventually diagnosed with Blau syndrome.

• BMB Reports
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• v.32 no.5
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• pp.419-428
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• 1999

Tumor necrosis factor (TNF) receptor members have unique structures composed of 2-4 cysteine - rich pseudorepeats in the extracellular domain. On ligation by trimeric ligand molecules, oligomerization of three receptor molecules occurs, which in turn activates the receptor and recruits intracellular signaling molecules to the cytoplasmic tail to initiate biological events. Recently, the numbers of tumor necrosis factor receptor and ligand family members have been rapidly expanding. Functional characterization of the new members has indicated redundant roles with other known members as well as provided insights into novel functions. In particular, identification of soluble decoy receptors which have the ability to bind multiple ligands highlights a complex control mechanism of immune responses by these molecules. Studies of the new members have also revealed that the TNF receptor and ligand family members play an important role in other than the immune system.

• Journal of the Korean Chemical Society
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• v.12 no.3
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• pp.128-137
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• 1968

In the oligomerization of p-aminophenol by the catalytic action of Fe-EDTA complex in the aqueous medium, the mixed complex intermediate, Fe-EDTA-M type, is considered to be formed, from which active radicals of the monomer are produced. In this system, polymerization is presumed to proceed as follows: Free radical formation ${\to}$ Coupling ${\to}$ Activation ${\to}$ Coupling, and so on. In this study, the form of the monomer and coordination state in the mixed complex, the catalytic action of Fe-EDTA the complex, the reaction mechanism, and the structure of the oligomers are discussed.