• Molecules and Cells
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• v.23 no.1
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• pp.94-99
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• 2007

Suppressors of cytokine signaling (SOCS) family members are negative feedback regulators of the Jak/Stat pathway, which is an essential inflammatory signaling pathway. We investigated expression of eight members of the SOCS family in rat astrocytes, using two inflammatory stimulants, PMA and IFN-${\gamma}$. Only a few SOCS genes were induced by both stimulants, and we detected an increase in SOCS5 protein with PMA. PMA activated the Jnk, Erk, p38, and Jak/Stat signal pathways. In addition, it increased the level of activated-Stat3 resulting from tyrosine phosphorylation. A gel-shift assay showed that a protein in nuclear extracts from PMA-treated cells was able to bind to Stat binding elements. These results suggest that activated Stat3 binds to SOCS promoters and leads to their transcriptional induction.

• Parasites, Hosts and Diseases
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• v.62 no.1
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• pp.30-41
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• 2024

The dense granule protein of Toxoplasma gondii, inhibitor of signal transducer and activator of transcription 1 (IST) is an inhibitor of signal transducer and activator of transcription 1 (STAT1) transcriptional activity that binds to STAT1 and regulates the expression of inflammatory molecules in host cells. A sterile inflammatory liver injury in pathological acute liver failures occurs when excessive innate immune function, such as the massive release of IFN-γ and TNF-α, is activated without infection. In relation to inflammatory liver injury, we hypothesized that Toxoplasma gondii inhibitor of STAT1 transcription (TgIST) can inhibit the inflammatory response induced by activating the STAT1/IRF-1 mechanism in liver inflammation. This study used IFN-γ and TNF-α as inflammatory inducers at the cellular level of murine hepatocytes (Hepa-1c1c7) to determine whether TgIST inhibits the STAT1/IRF-1 axis. In stable cells transfected with TgIST, STAT1 expression decreased with a decrease in interferon regulatory factor (IRF)-1 levels. Furthermore, STAT1 inhibition of TgIST resulted in lower levels of NF-κB and COX2, as well as significantly lower levels of class II transactivator (CIITA), iNOS, and chemokines (CLXCL9/10/11). TgIST also significantly reduced the expression of hepatocyte proapoptotic markers (Caspase3/8/9, P53, and BAX), which are linked to sterile inflammatory liver injury. TgIST also reduced the expression of adhesion (ICAM-1 and VCAM-1) and infiltration markers of programmed death-ligand 1 (PD-L1) induced by hepatocyte and tissue damage. TgIST restored the cell apoptosis induced by IFN-γ/TNF-α stimulation. These results suggest that TgIST can inhibit STAT1-mediated inflammatory and apoptotic responses in hepatocytes stimulated with proinflammatory cytokines.

• Journal of Life Science
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• v.32 no.2
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• pp.125-134
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• 2022

This study investigated whether or not the major bioactive compounds of Noni (Morinda citrifolia) are involved in anti-inflammatory activity through the JAK/STAT upper signaling pathway in RAW 264.7 cells. The experimental results show that the M. citrifolia ethyl acetate fraction (Mc-EtOAc) obtained by sequential fractionation with organic solvents from the plant's dried fruits exhibits the highest antioxidant activity. In addition, the cytoprotective effects of Mc-EtOAc against H₂O₂-induced oxidative stress in the RAW 264.7 cells suppressed cytotoxicity in a dose-dependent manner. The group pretreated with Mc-EtOAc at a concentration of 240 ㎍/ml showed higher cell viability of 84.5%, compared to 71.6% in the LPS-treated group, and LPS-induced NO production decreased to half the amount in the positive control group. Mc-EtOAc treatment also led to a significant dose-dependent reduction in iNOS expression. Although COX-2 expression was increased by 300% following LPS induction, it was significantly decreased in a dose-dependent manner by pretreatment with Mc-EtOAc at concentrations of 120 and 240 ㎍/ml. An inhibition of the mRNA expression of pro-inflammatory cytokines IL-1β and TNF-α was observed. The investigation also revealed that the phosphorylation levels of pJAK1 and pSTAT3 in LPS-induced RAW 264.7 cells were significantly reduced by Mc-EtOAc treatment.

• IMMUNE NETWORK
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• v.23 no.6
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• pp.46.1-46.16
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• 2023

Autoimmune hepatitis (AIH) affects all age group and occurs mainly in women. Pyroptosis is a novel programmed cell death featured with cell bursting and release of proinflammatory cytokines. A deeper understanding of AIH pathogenesis will contribute to novel therapy for AIH patients. Here, we aimed to investigate the role of IL-17 in immune-mediated liver injury. The levels of cytokines were measured by ELISA, and mRNA levels of STAT3 and IFN gamma-inducible protein 16 (IFI16) were detected by PCR. Expressions of STAT3, IFI16, gasdermin D and cleaved caspase-1 were measured by western-blotting. Immunohistochemical staining and transmission electron microscopy were applied to evaluate liver histopathological changes of the treated mice. Our results showed that the levels of IFI16 was increased in hepatocytes treated with IL-17 protein, and further elevated after STAT3-overexpressed (STAT3-OE) lentivirus treatment. The levels of IFI16 were reduced in hepatocytes treated with IL-17 neutralizing Ab (nAb), but were significantly increased after STAT3-OE treatment. Pyroptosis was observed in hepatocytes treated with IL-17 protein, and further cell damage was observed after STAT3-OE lentivirus treatment. Liver damage was alleviated in mice treated with IL-17 nAb, however sever damage was experienced after STAT3-OE lentivirus treatment. A binding interaction between IFI16 and STAT3 was detected in IL-17 treated hepatocytes. Glutathione transaminase activity was enhanced in concanavalin A-induced AIH mice compared to the control group (p<0.01). IL-17 plays an important role in activating STAT3 and up-regulating IFI16, which may promote the pyroptosis in AIH-related liver injury through STAT3-IFI16 axis.

• International Journal of Oral Biology
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• v.44 no.1
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• pp.20-26
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• 2019

Periodontal diseases have been associated with the development of cardiovascular diseases. Accumulating evidences have indicated that Porphyromonas gingivalis, a major periodontopathic pathogen, plays a critical role in the pathogenesis of atherosclerosis. In the present study, we demonstrated that P. gingivalis lipopolysaccharide (LPS) increases the mRNA and protein expression of matrix metalloproteinase-9 (MMP-9) in rat vascular smooth muscle cells. We showed that the MMP-9 expression induced by P. gingivalis LPS is mediated by the activation of signal transducer and activator of transcription 3 (STAT3) in vascular smooth muscle cells. Furthermore, the inhibition of STAT3 activity reduced P. gingivalis LPS-induced migration of vascular smooth muscle cells. Overall, our findings indicate that P. gingivalis LPS stimulates the migration of vascular smooth muscle cells via STAT3-mediated MMP-9 expression.

• The Korean Journal of Physiology and Pharmacology
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• v.19 no.2
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• pp.105-109
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• 2015

NgR1, a Nogo receptor, is involved in inhibition of neurite outgrowth and axonal regeneration and regulation of synaptic plasticity. P19 embryonal carcinoma cells were induced to differentiate into neuron-like cells using all trans-retinoic acid and the presence and/or function of cellular molecules, such as NgR1, NMDA receptors and STAT3, were examined. Neuronally differentiated P19 cells expressed the mRNA and protein of NgR1, which could stimulate the phosphorylation of STAT3 when activated by Nogo-P4 peptide, an active segment of Nogo-66. During the whole period of differentiation, mRNAs of all of the NMDA receptor subtypes tested (NR1, NR2A-2D) were consistently expressed, which meant that neuronally differentiated P19 cells maintained some characteristics of neurons, especially central nervous system neurons. Our results suggests that neuronally differentiated P19 cells expressing NgR1 may be an efficient and convenient in vitro model for studying the molecular mechanism of cellular events that involve NgR1 and its binding partners, and for screening compounds that activate or inhibit NgR1.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.35 no.2
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• pp.13-27
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• 2022

목적 : 본 연구는 인간피부각질형성세포(HaCaT keratinocytes) 모델을 TNF-α와 IFN-γ로 자극하여 내복자(萊菔子)의 피부염증 감소 및 만성 염증성 질환에 미치는 영향을 알아보고자 하였다. 방법 : 내복자(萊菔子) 에탄올 추출물(RSE)이 세포생존율에 미치는 영향을 확인하기 위하여 MTT assay를 시행하였다. 또한 RSE가 TNF-α와 IFN-γ로 자극한 HaCaT 세포에서 p-IκBα, p-ERK, p-JAK2, p-STAT1, p-STAT6의 발현과 periostin, TSLP 단백질 발현에 미치는 영향을 확인하였다. 결과 : RSE는 200㎍/㎖ 이하에서 세포 독성을 보이지 않았고, HaCaT keratinocytes에서 TNF-α와 IFN-γ자극에 의하여 증가된 IκBα, ERK의 인산화를 억제하였다. 또한 JAK2와 STAT1, STAT6의 인산화를 억제하였으며, periostin과 TSLP의 발현을 감소시켰다. 결론 : RSE는 HaCaT keratinocytes에서 pro-inflammatory cytokines 및 transcription factors의 발현을 감소시켜 피부염증 감소 효능을 보였고, 만성 염증성 질환에서 내복자(萊菔子)의 사용 가능성을 확인하였다.

• Genomics & Informatics
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• v.2 no.3
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• pp.126-130
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• 2004

T helper-type 2 cytokines, such as IL-4 and IL-13, may play a central role in allergic diseases. The protein known as signal transducers and activators of transcription 6 (STAT6) is a key transcription factor involved in both IL-4- and -13-mediated biological responses. Two polymorphisms of the STAT 6 gene (exon 1 and G2964A variant) have been found. We investigated whether these STAT6 gene polymorph isms were associated with allergic rhinitis. Blood samples for genetic analysis were obtained from 285 individuals with allergic rhinitis and from 271 healthy subjects without atopic disease. The G2964A variant of the STAT6 gene was genotyped using PCR-RFLP analysis. The GT repeat polymorphism in exon 1 of the STAT6 gene was genotyped by fragment analysis. There was no association between the 2964A variant and GT repeat polymorphism in exon 1 of the STAT6 and allergic rhinitis in a Korean population (both p > 0.05). Our results suggest that a combination of STAT6 gene polymorphisms is not a useful marker for predicting allergic rhinitis.

• Journal of Acupuncture Research
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• v.34 no.1
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• pp.23-30
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• 2017

Objectives : In this study, the roles of Interleukin (IL)-4 and Signal transducer and activator of transcription 6 (STAT6), which have been reported to play a role in the pathogenesis of inflammation and cancer, were evaluated in snake venom toxin (SVT)-induced apoptosis. Methods : Inflammation was induced in human HaCaT kerationocytes, by lipopolysaccharide (LPS; $1{\mu}g/mL$) or tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$), followed by treatment with SVT (0, 1, or $2{\mu}g/mL$). Cell viability was assessed by MTT assays after 24 h, and the expression of levels of IL-4, STAT6, and the apoptosis-related proteins p53, Bax, and Bcl-2 were evaluated by western blotting. Electro mobility shift assays (EMSAs) were performed to evaluate the DNA binding capacity of STAT6. Results : MTT assays showed that inflammation-induced growth of HaCaT cells following LPS or TNF-${\alpha}$ stimulation was inhibited by SVT. Western blot analysis showed that p53 and Bax, which promote apoptosis, were increased, whereas that of Bcl-2, an anti-apoptotic protein, was decreased in a concentration-dependent manner in LPS- or TNF-${\alpha}$-induced HaCaT cells following treatment with SVT. Moreover, following treatment of HaCaT cells with LPS, IL-4 concentrations were increased, and treatment with SVT further increased IL-4 expression in a concentration-dependent manner. Western blotting and EMSAs showed that the phosphorylated form of STAT6 was increased in HaCaT cells in the context of LPS- or TNF-${\alpha}$-induced inflammation in a concentration-dependent manner, concomitant with an increase in the DNA binding activity of STAT6. Conclusion : SVT can effectively promote apoptosis in HaCaT cells in the presence of inflammation through a pathway involving IL-4 and STAT6.

• Nutrition Research and Practice
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• v.17 no.6
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• pp.1070-1083
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• 2023

BACKGROUND/OBJECTIVES: Sanghuangporus sanghuang (SS) has various medicinal effects, including anti-inflammation and anticancer activities. Despite the extensive research on SS, its molecular mechanisms of action on lung cancer are unclear. This study examined the impact of an SS alcohol extract (SAE) on lung cancer using in vitro and in vivo models. MATERIALS/METHODS: Different concentrations of SAE were used to culture lung cancer cells (A549 and H1650). A cell counting kit-8 assay was used to detect the survival ability of A549 and H1650 cells. A scratch assay and transwell cell invasion assay were used to detect the migration rate and invasive ability of SAE. Western blot analysis was used to detect the expression of B-cell lymphoma-2 (Bcl-2), Bcl2-associated X (Bax), cyclin D1, cyclin-dependent kinases 4 (CDK4), signal transducer and activator of transcription 3 (STAT3), and phosphorylated STAT3 (p-STAT3). Lung cancer xenograft mice were used to detect the inhibiting ability of SAE in vivo. Hematoxylin and eosin staining and immunohistochemistry were used to detect the effect of SAE on the structural changes to the tumor and the expression of Bcl-2, Bax, cyclin D1, CDK4, STAT3, and p-STAT3 in lung cancer xenograft mice. RESULTS: SAE could inhibit lung cancer proliferation significantly in vitro and in vivo without cytotoxicity. SAE suppressed the viability, migration, and invasion of lung cancer cells in a dose and time-dependent manner. The SAE treatment significantly decreased the proapoptotic Bcl-2/Bax ratio and the expression of pro-proliferative proteins Cyclin D1 and CDK4 in vitro and in vivo. Furthermore, SAE also inhibited STAT3 expression. CONCLUSIONS: SAE reduced the cell viability and suppressed cell migration and invasion in human lung cancer cells. Moreover, SAE also exhibited anti-proliferation effects in vivo. Therefore, SAE may have benefits in cancer therapy.