• Parasites, Hosts and Diseases
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• 제62권1호
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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.

• The Korean Journal of Physiology and Pharmacology
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• 제12권5호
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• pp.281-286
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• 2008

Although the interaction between gp130 and the ErbB family has frequently been shown in cancer cells, the mechanism of this interaction remains unclear and controversial. In the present study, we found that specific tyrphostin inhibitors of ErbB2 (AG825 and AG879), but not ErbB1 inhibitor (AG1478), suppressed IL-6-induced tyrosine phosphorylation of STAT3 in schwannoma cells. However, biochemical evidence for transactivation of ErbB2 by IL-6 was not observed. Additionally, the inhibition of ErbB2 expression, with either a specific RNAi or transfection of an ErbB2 mutant lacking the intracellular domain did not inhibit the IL-6-induced tyrosine phosphorylation of STAT3. Thus, it seems that tyrphostins, which are known as specific inhibitors of the ErbB2 kinase, may have non-specific suppressive effects on the IL-6/STAT3 pathway.

• 생명과학회지
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• 제32권2호
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• pp.125-134
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• 2022

본 연구는 노니(Morinda citrifolia)에 함유된 주요 생리활성물질이 RAW 264.7 세포에서 JAK/STAT 신호전달 경로를 통하여 항염증 작용에 관여하는 것을 조사하였다. 건조된 M. citrifolia 열매의 MeOH 추출에 의한 유기용매의 순차 분획에서 얻은 EtOAc 분획물(Mc-EtOAc)에서 가장 높은 항산화 활성을 확인하였고, H₂O₂로 유도된 RAW 264.7 세포의 산화적 스트레스에 대한 세포보호 효과는 처리 농도의존적으로 세포독성을 차단하였다. LPS 처리로 71.6%의 RAW 264.7 세포 생존율에서 240 ㎍/ml의 Mc-EtOAc를 전처리한 군에서 84.5%의 세포 생존율 증가를 보였다. LPS로 유도된 RAW 264.7 세포의 NO 생성 저해활성은 240 ㎍/ml의 Mc-EtOAc에서 양성 대조군의 절반 수준으로 NO의 생성양을 감소시켰다. Mc-EtOAc 처리로 iNOS의 발현량은 농도의존적으로 유의하게 감소하였고, COX-2의 발현은 LPS 유도로 3배 정도로 증가되었으나, 120, 240 ㎍/ml의 Mc-EtOAc를 전처리시 농도의존적으로 유의하게 감소시켰다. 또한 pro-inflammatory cytokine IL-1β와 TNF-α의 mRNA 발현도 억제하였다. 이러한 Mc-EtOAc의 항염증 작용이 상위 신호전달 경로인 JAK/STAT 신호전달 경로 통해 일어나지를 조사한 결과, Mc-EtOAc의 전처리로 LPS로 유도된 RAW 264.7 세포에서 pJAK1과 pSTAT3의 인산화 정도가 유의성 있게 감소하였다. 따라서 RAW 264.7 세포에서 Mc-EtOAc의 항염증 효과는 JAK1/STAT3 신호전달 경로를 통해 염증반응을 억제하는 것으로 사료된다.

• 생명과학회지
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• 제29권5호
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• pp.514-523
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• 2019

인삼(Panax ginseng C. A. Meyer)의 사포닌 진세노사이드 Rb1이 처리된 인간 피부각질세포 HaCaT에서 microarray 분석 및 발현이 증가된 세포사멸 반응에 대한 작용기전을 연구하였다. HaCaT 세포에 진세노사이드 Rb1의 처리로 세포사멸, 유사분열 세포주기의 G2/M 전이, 세포분열, 핵분열, 그리고 단백질 수송 등의 작용기전에 관여하는 유전자들이 2 배 이상 발현이 증가된 것으로 나타났으며, DNA 수선, 감수 핵분열, 그리고 세포외기질 체계 등의 작용기전에 관여하는 유전자들은 2 배 이상 발현이 감소된 것으로 나타났다. 특히 세포사멸 신호전달은 FAS와 PLA2G4A를 경유하는 것으로 나타났으며, 이들 유전자의 상위 조절자로 STAT3가 예측되었다. 세포사멸 반응 경유 유전자 FAS와 PLA2G4A의 활성을 qPCR로 확인한 결과, FAS 유전자는 $10{\mu}g/ml$의 진세노사이드 Rb1를 24시간 동안 처리하였을 경우 약 2 배의 발현 증가와, PLA2G4A 유전자는 6시간 처리부터 약 2 배로 증가되어 24시간 동안 처리시 2 배 이상의 유전자 발현이 증가되었다. 한편 STAT3-siRNA를 이용한 knock-down 실험에서 FAS의 발현 감소와 PLA2G4A의 발현 증가로 상위 조절자 STAT3로부터 FAS 만을 경유하는 것을 알 수 있었다. 이상의 결과 진세노사이드 Rb1의 처리에 의해 상위 조절자인 STAT3는 FAS를 경유하여 세포사멸을 유도하는 것임을 알 수 있다.

• IMMUNE NETWORK
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• 제10권6호
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• pp.219-229
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• 2010

Background: N-myc downstream regulated gene 2 (NDRG2) is a member of the NDRG gene family. Our previous report indicated a possible role for NDRG2 in regulating the cytokine, interleukin-10 (IL-10), which is an important immunosuppressive cytokine. Several pathways, including p38-MAPK, NF-${\kappa}B$, and JAK/STAT, are used for IL-10 production, and the JAK/STAT pathway can be inhibited in a negative feedback loop by the inducible protein, SOCS3. In the present study, we investigated the effect of NDRG2 gene expression on IL-10 signaling pathway that is modulated via SOCS3 and STAT3. Methods: We generated NDRG2-overexpressing U937 cell line (U937-NDRG2) and treated the cells with PMA to investigate the role of NDRG2 in IL-10 production. U937 cells were also transfected with SOCS3- or NDRG2-specific siRNAs to examine whether the knockdown of SOCS3 or NDRG2 influenced IL-10 expression. Lastly, STAT3 and SOCS3 induction was measured to identify the signaling pathway that was associated with IL-10 production. Results: RT-PCR and ELISA assays showed that IL-10 was increased in U937-mock cells upon stimulation with PMA, but IL-10 was inhibited by overexpression NDRG2. After PMA treatment, STAT3 phosphorylation was decreased in a time-dependent manner in U937-mock cells, whereas it was maintained in U937-NDRG2 cells. SOCS3 was markedly reduced in U937-NDRG2 cells compared with U937-mock cells. IL-10 production after PMA stimulation was reduced in U937 cells when SOCS3 was inhibited, but this effect was less severe when NDRG2 was inhibited. Conclusion: NDRG2 expression modulates SOCS3 and STAT3 activity, eventually leading to the inhibition of IL-10 production.

• Biomolecules & Therapeutics
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• 제25권5호
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• pp.535-544
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• 2017

Carnosol is a phenolic antioxidant present in rosemary (Rosmarinus officinalis). It is known for anti-inflammatory effects, analgesic activity and anti-cancer effects. However, no study has been dedicated yet to its effect on atopic dermatitis (AD). Here, we show that carnosol effectively inhibited LPS-induced nitric oxide (NO) generation and expression of inflammatory marker proteins (iNOS and COX-2) in RAW 264.7 cells. In addition, carnosol effectively inhibits the phosphorylation of STAT3 and DNA binding activity in RAW 264.7 cells. Pull down assay and docking model analysis showed that carnosol directly binds to the DNA binding domain (DBD) of STAT3. We next examined the anti-atopic activity of carnosol ($0.05{\mu}g/cm^2$) using 5% Phthalic anhydride (PA)-induced AD model in HR1 mice. Carnosol treatment significantly reduced 5% PA-induced AD like skin inflammation in skin tissues compared with control mice. Moreover, carnosol treatment inhibits the expression of iNOS and COX-2 in skin tissue. In addition, the levels of $TNF-{\alpha}$, $IL-1{\beta}$, and Immunoglobulin-E in blood serum was significantly decreased in carnosol treated mice compared with those of 5% PA treated group. Furthermore, the activation of STAT3 in skin tissue was decreased in carnosol treated mice compared with control mice. In conclusion, these findings suggest that carnosol exhibited a potential anti-AD activity by inhibiting pro-inflammatory mediators through suppression of STAT3 activation via direct binding to DBD of STAT3.

• Molecules and Cells
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• 제38권5호
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• pp.441-451
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• 2015

Recognition of cytosolic DNA initiates a series of innate immune responses by inducing IFN-I production and subsequent triggering JAK1-STAT1 signaling which plays critical roles in the pathogenesis of infection, inflammation and autoimmune diseases through promoting B cell activation and antibody responses. The stimulator of interferon genes protein (STING) has been demonstrated to be a critical hub of type I IFN induction in cytosolic DNA-sensing pathways. However, it still remains unknown whether cytosolic DNA can directly activate the JAK1-STAT1 signaling or not. And the role of STING is also unclear in this response. In the present study, we found that dsDNA directly triggered the JAK1-STAT1 signaling by inducing phosphorylation of the Lyn kinase. Moreover, this response is not dependent on type I IFN receptors. Interestingly, STING could inhibit dsDNA-triggered activation of JAK1-STAT1 signaling by inducing SHP-1 and SHP-2 phosphorylation. In addition, compared with normal B cells, the expression of STING was significantly lower and the phosphorylation level of JAK1 was significantly higher in B cells from MRL/lpr lupus-prone mice, highlighting the close association between STING low-expression and JAK1-STAT1 signaling activation in B cells in autoimmune diseases. Our data provide a molecular insight into the novel role of STING in dsDNA-mediated inflammatory disorders.

• Biomolecules & Therapeutics
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• 제24권5호
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• pp.489-494
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• 2016

Neuropathic pain (NPP) is the main culprit among chronic pains affecting the normal life of patients. Procaine is a frequently-used local anesthesia with multiple efficacies in various diseases. However, its role in modulating NPP has not been reported yet. This study aims at uncovering the role of procaine in NPP. Rats were pretreated with procaine by intrathecal injection. Then NPP rat model was induced by sciatic nerve chronic compression injury (CCI) and behavior tests were performed to analyze the pain behaviors upon mechanical, thermal and cold stimulations. Spinal expression of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) was detected by qRT-PCR and western blot. JAK2 was also overexpressed in procaine treated model rats for behavior tests. Results showed that procaine pretreatment improved the pain behaviors of model rats upon mechanical, thermal and cold stimulations, with the best effect occurring on the $15^{th}$ day post model construction (p<0.05). Procaine also inhibited JAK2 and STAT3 expression in both mRNA (p<0.05) and protein levels. Overexpression of JAK2 increased STAT3 level and reversed the improvement effects of procaine in pain behaviors (p<0.01). These findings indicate that procaine is capable of attenuating NPP, suggesting procaine is a potential therapeutic strategy for treating NPP. Its role may be associated with the inhibition on JAK2/STAT3 signaling.

• 치위생과학회지
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• 제17권1호
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• pp.81-86
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• 2017

Bacterial infection and smoking are an important risk factors involved in the development and progression of periodontitis. However, the signaling mechanism underlying the host immune response is not fully understood in periodontal lesions. In this study, we determined the expression of janus kinase (JAK)/signal transducer and activator of transcription (STAT) on Porphyromonas gingivalis lipopolysaccharide (LPS)- and nicotine-induced cytotoxicity and the production of inflammatory mediators, using osteoblasts. The cells were cultured with 5 mM nicotine in the presence of $1{\mu}g/ml$ LPS. Cell viability was determined using MTT assay. The role of JAK on inflammatory mediator expression and production, and the regulatory mechanisms involved were assessed via enzyme-linked immunosorbent assay, reverse transcription-polymerase chain reaction, and Western blot analysis. LPS- and nicotine synergistically induced the production of cyclooxgenase-2 (COX-2) and prostaglandin $E_2$ ($PGE_2$) and increased the protein expression of JAK/STAT. Treatment with an JAK inhibitor blocked the production of COX-2 and $PGE_2$ as well as the expression of pro-inflammatory cytokines, such as tumor necrosis factor-${\alpha}$, interleukin-$1{\beta}$ ($IL-1{\beta}$), and IL-6 in LPS- and nicotine-stimulated osteoblasts. These results suggest that JAK/STAT is closely related to the LPS- and nicotine-induced inflammatory effects and is likely to regulate the immune response in periodontal disease associated with dental plaque and smoking.

• Nutrition Research and Practice
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• 제17권6호
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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.