• BMB Reports
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• 제51권10호
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• pp.508-513
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• 2018

Fibronectin fragments found in the synovial fluid of patients with osteoarthritis (OA) induce the catabolic responses in cartilage. Nuclear high-mobility group protein Box 1 (HMGB1), a damage-associated molecular pattern, is responsible for the regulation of signaling pathways related to cell death and survival in response to various stimuli. In this study, we investigated whether changes induced by 29-kDa amino-terminal fibronectin fragment (29-kDa FN-f) in HMGB1 expression influences the pathogenesis of OA via an HMGB1-modulated autophagy signaling pathway. Human articular chondrocytes were enzymatically isolated from articular cartilage. The level of mRNA was measured by quantitative real-time PCR. The expression of proteins was examined by western blot analysis, immnunofluorescence assay, and enzyme-linked immunosorbent assay. Interaction of proteins was evaluated by immunoprecipitation. The HMGB1 level was significantly lower in human OA cartilage than in normal cartilage. Although 29-kDa FN-f significantly reduced the HMGB1 expression at the mRNA and protein levels 6 h after treatment, the cytoplasmic level of HMGB1 was increased in chondrocytes treated with 29-kDa FN-f, which significantly inhibited the interaction of HMGB1 with Beclin-1, increased the interaction of Bcl-2 with Beclin-1, and decreased the levels of Beclin-1 and phosphorylated Bcl-2. In addition, the level of microtubule-associated protein 1 light chain 3-II, an autophagy marker, was down-regulated in chondrocytes treated with 29-kDa FN-f, whereas the effect was antagonized by mTOR knockdown. Furthermore, prolonged treatment with 29-kDa FN-f significantly increased the release of HMGB1 into the culture medium. These results demonstrated that 29-kDa FN-f inhibits chondrocyte autophagy by modulating the HMGB1 signaling pathway.

• IMMUNE NETWORK
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• 제22권3호
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• pp.21.1-21.21
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• 2022

As far the current severe coronavirus disease 2019 (COVID-19), respiratory disease is still the biggest threat to human health. In addition, infectious respiratory diseases are particularly prominent. In addition to killing and clearing the infection pathogen directly, regulating the immune responses against the pathogens is also an important therapeutic modality. Sirtuins belong to NAD+-dependent class III histone deacetylases. Among 7 types of sirtuins, silent information regulator type-1 (SIRT1) played a multitasking role in modulating a wide range of physiological processes, including oxidative stress, inflammation, cell apoptosis, autophagy, antibacterial and antiviral functions. It showed a critical effect in regulating immune responses by deacetylation modification, especially through high-mobility group box 1 (HMGB1), a core molecule regulating the immune system. SIRT1 was associated with many respiratory diseases, including COVID-19 infection, bacterial pneumonia, tuberculosis, and so on. Here, we reviewed the latest research progress regarding the effects of SIRT1 on immune system in respiratory diseases. First, the structure and catalytic characteristics of SIRT1 were introduced. Next, the roles of SIRT1, and the mechanisms underlying the immune regulatory effect through HMGB1, as well as the specific activators/inhibitors of SIRT1, were elaborated. Finally, the multitasking roles of SIRT1 in several respiratory diseases were discussed separately. Taken together, this review implied that SIRT1 could serve as a promising specific therapeutic target for the treatment of respiratory diseases.

• BMB Reports
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• 제50권11호
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• pp.590-595
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• 2017

High-mobility group box-1 (HMGB-1) is expressed in almost all cells, and its dysregulated expression correlates with inflammatory diseases, ischemia, and cancer. Some of these conditions accompany HMGB-1-mediated abnormal angiogenesis. Thus far, the mechanism of HMGB-1-induced angiogenesis remains largely unknown. In this study, we performed time-dependent DNA microarray analysis of endothelial cells (ECs) after HMGB-1 or VEGF treatment. The pathway analysis of each gene set upregulated by HMGB-1 or VEGF showed that most HMGB-1-induced angiogenic pathways were also activated by VEGF, although the activation time and gene sets belonging to the pathways differed. In addition, HMGB-1 upregulated some VEGFR signaling-related angiogenic factors including EGR1 and, importantly, novel angiogenic factors, such as ABL2, CEACAM1, KIT, and VIPR1, which are reported to independently promote angiogenesis under physiological and pathological conditions. Our findings suggest that HMGB-1 independently induces angiogenesis by activating HMGB-1-specific angiogenic factors and also functions as an accelerator for VEGF-mediated conventional angiogenesis.

• Bulletin of the Korean Chemical Society
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• 제35권10호
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• pp.2955-2962
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• 2014

Asian ginseng is used as a treatment for cardiovascular diseases, ischemia, and cancers. High mobility group box 1 (HMGB1) protein acts as a late mediator of severe vascular inflammatory conditions. However, the effect of ginsenosides from Asian ginseng on HMGB1-induced inflammatory responses has not been studied. We addressed this question by monitoring the effects of ginsenoside treatment on lipopolysaccharide (LPS) and cecal ligation and puncture (CLP)-mediated release of HMGB1, and HMGB1-mediated regulation of proinflammatory responses. Ginsenoside treatment suppressed LPS-mediated release of HMGB1 and HMGB1-mediated cytoskeletal rearrangements. Ginsenosides also inhibited HMGB1-mediated inflammatory responses. In addition, ginsenosides inhibited the production of tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) and activation of protein kinase B (Akt), nuclear factor-${\kappa}B$ (NF-${\kappa}B$), and extracellular-regulated kinases (ERK) 1/2 by HMGB1. Ginsenosides also decreased CLP-induced release of HMGB1, production of interleukin (IL) $1{\beta}/6$, and mortality. These results suggested that ginsenosides may be potential therapeutic agents for treatment of vascular inflammatory diseases through inhibition of the HMGB1 signaling pathway.

• Asian Pacific Journal of Cancer Prevention
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• 제14권1호
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• pp.359-365
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• 2013

The high mobility group box 1 (HMGB1) protein is a multifunctional cytokine-like molecule that plays an important role in the pathogenesis of tumors. In this study, real-time polymerase chain reactions and Western blot assays indicated that HMGB1 transcriptional activity and protein level are increased in $Tax^+$-T cells (TaxP). To clarify the mechanisms, a series of HMGB1 deletion reporter plasmids (pHLuc1 to pHLuc6) were transfected into $Tax^-$-T cells (TaxN, Jurkat) and $Tax^+$-T cells (TaxP). We found that promoter activity in $Tax^+$-T cells to be higher than that in $Tax^-$-T cells, indicating a significant increase in pHLuc6. Bay11-7082 (NF-${\kappa}B$ inhibitor) treatment did not block the enhancing effect. Chromatin immunoprecipitation assays revealed that Tax was retained on a HMGB1 promoter fragment encompassing -1163 to -975. Bioinformatics analysis showed six characteristic cis-elements for CdxA, AP-1, AML-1a, USF, v-Myb, and C/EBP in the fragment in question. Mutation of cis-elements for C/EBP reduced significant HMGB1 promoter activity induced by Tax. These findings indicate that Tax enhances the expression of HMGB1 gene at the transcriptional level, possibly by interacting with C/EBP.

• Biomolecules & Therapeutics
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• 제23권6호
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• pp.549-556
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• 2015

Consumption of herbal tea [flower buds of Cleistocalyx operculatus (Roxb.) Merr. et Perry (Myrtaceae)] is associated with health beneficial effects against multiple diseases including diabetes, asthma, and inflammatory bowel disease. Emerging evidences have reported that High mobility group box 1 (HMGB1) is considered as a key "late" proinflammatory factor by its unique secretion pattern in aforementioned diseases. Dimethyl cardamonin (2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone, DMC) is a major ingredient of C. operculatus flower buds. In this study, the anti-inflammatory effects of DMC and its underlying molecular mechanisms were investigated on lipopolysaccharide (LPS)-induced macrophages. DMC notably suppressed the mRNA expressions of TNF-${\alpha}$, IL-$1{\beta}$, IL-6, and HMGB1, and also markedly decreased their productions in a time- and dose-dependent manner. Intriguingly, DMC could notably reduce LPS-stimulated HMGB1 secretion and its nucleo-cytoplasmic translocation. Furthermore, DMC dose-dependently inhibited the activation of phosphatidylinositol 3-kinase (PI3K), phosphoinositide-dependent kinase 1 (PDK1), and protein kinase C alpha (PKC${\alpha}$). All these data demonstrated that DMC had anti-inflammatory effects through reducing both early (TNF-${\alpha}$, IL-$1{\beta}$, and IL-6) and late (HMGB1) cytokines expressions via interfering with the PI3K-PDK1-PKC${\alpha}$ signaling pathway.

• Asian Pacific Journal of Cancer Prevention
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• 제16권12호
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• pp.4981-4985
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• 2015

Background: Colorectal cancer (CRC) is a leading cause of morbidity and mortality worldwide. Targeting autophagic cell death is emerging as a novel strategy in cancer chemotherapy. Aldose reductase (AR) catalyzes the rate limiting step of the polyol pathway of glucose metabolism; besides reducing glucose to sorbitol, AR reduces lipid peroxidation-derived aldehydes and their glutathione conjugates. A complex interplay between autophagic cell death and/or survival may in turn govern tumor metastasis. This exploratory study aimed to investigate the potential role of AR inhibition using a novel inhibitor Fidarestat in the regulation of autophagy in CRC cells. Materials and Methods: For glucose depletion (GD), HT-29 and SW480 CRC cells were rinsed with glucose-free RPMI-1640, followed by incubation in GD medium +/- Fidarestat ($10{\mu}M$). Proteins were extracted by a RIPA-method followed by Western blotting ($35-50{\mu}g$ of protein; n=3). Results: Autophagic regulatory markers, primarily, microtubule associated protein light chain (LC) 3, autophagy-related gene (ATG) 5, ATG 7 and Beclin-1 were expressed in CRC cells; glyceraldehyde-3 phosphate dehydrogenase (GAPDH) was used as an internal reference. LC3 II (14 kDa) expression was relatively high compared to LC3A/B I levels in both CRC cell lines, suggesting occurrence of autophagy. Expression of non-autophagic markers, high mobility group box (HMG)-1 and Bcl-2, was comparatively low. Conclusions: GD +/- ARI induced autophagy in HT-29 and SW-480 cells, thereby implicating Fidarestat as a promising therapeutic agent for colorectal cancer; future studies with more potent ARIs are warranted to fully dissect the molecular regulatory networks for autophagy in colorectal carcinoma.

• BMB Reports
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• 제49권4호
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• pp.214-219
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• 2016

A nucleosomal protein, high mobility group box 1 (HMGB1) is known to be a late mediator of sepsis. Dabrafenib is a B-Raf inhibitor and initially used for the treatment of metastatic melanoma therapy. Inhibition of HMGB1 and renewal of vascular integrity is appearing as an engaging therapeutic strategy in the administration of severe sepsis or septic shock. Here, we examined the effects of dabrafenib (DAB) on the modulation of HMGB1-mediated septic responses. DAB inhibited the release of HMGB1 and downregulated HMGB1-dependent inflammatory responses by enhancing the expressions of cell adhesion molecules (CAMs) in human endothelial cells. In addition, treatment with DAB inhibited the HMGB1 secretion by CLP and sepsis-related mortality and pulmonary injury. This study demonstrated that DAB could be alternative therapeutic options for sepsis or septic shock via the inhibition of the HMGB1 signaling pathway.

• IMMUNE NETWORK
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• 제23권3호
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• pp.25.1-25.17
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• 2023

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection induces excessive pro-inflammatory cytokine release and cell death, leading to organ damage and mortality. High-mobility group box 1 (HMGB1) is one of the damage-associated molecular patterns that can be secreted by pro-inflammatory stimuli, including viral infections, and its excessive secretion levels are related to a variety of inflammatory diseases. Here, the aim of the study was to show that SARS-CoV-2 infection induced HMGB1 secretion via active and passive release. Active HMGB1 secretion was mediated by post-translational modifications, such as acetylation, phosphorylation, and oxidation in HEK293E/ACE2-C-GFP and Calu-3 cells during SARS-CoV-2 infection. Passive release of HMGB1 has been linked to various types of cell death; however, we demonstrated for the first time that PANoptosis, which integrates other cell death pathways, including pyroptosis, apoptosis, and necroptosis, is related to passive HMGB1 release during SARS-CoV-2 infection. In addition, cytoplasmic translocation and extracellular secretion or release of HMGB1 were confirmed via immunohistochemistry and immunofluorescence in the lung tissues of humans and angiotensin-converting enzyme 2-overexpressing mice infected with SARS-CoV-2.

• The Korean Journal of Physiology and Pharmacology
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• 제26권5호
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• pp.389-396
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• 2022

The increased expression of receptors for advanced glycation end-product (RAGE) is known as a key player in the progression of vascular remodeling. However, the precise signal pathways regulating RAGE expression in vascular smooth muscle cells (VSMCs) in the injured vasculatures are unclear. Given the importance of mitogen-activated protein kinase (MAPK) signaling in cell proliferation, we investigated the importance of MAPK signaling in high-mobility group box 1 (HMGB1)-induced RAGE expression in VSMCs. In HMGB1 (100 ng/ml)-stimulated human VSMCs, the expression of RAGE mRNA and protein was increased in association with an increase in AGE-induced VSMC proliferation. The HMGB1-induced RAGE expression was attenuated in cells pretreated with inhibitors for ERK (PD98059, 10 μM) and p38 MAPK (SB203580, 10 μM) as well as in cells deficient in ERK and p38 MAPK using siRNAs, but not in cells deficient of JNK signaling. In cells stimulated with HMGB1, the phosphorylation of ERK, JNK, and p38 MAPK was increased. This increase in ERK and p38 MAPK phosphorylation was inhibited by p38 MAPK and ERK inhibitors, respectively, but not by JNK inhibitor. Moreover, AGE-induced VSMC proliferation in HMGB1-stimulated cells was attenuated in cells treated with ERK and p38 MAPK inhibitors. Taken together, our results indicate that ERK and p38 MAPK signaling are involved in RAGE expression in HMGB1-stimulated VSMCs. Thus, the ERK/p38 MAPK-RAGE signaling axis in VSMCs was suggested as a potential therapeutic target for vascular remodeling in the injured vasculatures.