• The Korean Journal of Physiology and Pharmacology
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• 제8권4호
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• pp.187-194
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• 2004

Middle cerebral artery occlusion (MCAO) results in cell death by activation of complex signal pathways for cell death and survival. Hypothermia is a robust neuroprotectant, and its effect has often been attributed to various mechanisms, but it is not yet clear. Upstream from the cell death promoters and executioners are several enzymes that may activate several transcription factors involved in cell death and survival. In this study, we immunohistochemically examined the phosphorylation of mitogen-activated protein kinase, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 kinase during early period of the ischemic injury, following 2 hours (h) of transient MCAO. Increased phosphorylation of ERK and p38 was observed in the vessels at 3 h, neuron-like cells at 6 and 12 h and glia-like cells at 12 h. Activation of JNK was not remarkable, and a few cells showed active JNK following ischemia. Phosphorylation of Elk-1, a transcription factor, was reduced by ischemic insult. Hypothermia attenuated the activation of ERK, p38 and JNK, and inhibited reduction of Elk-1. These data suggest that signals via different MAPK family members converge on the cell damage process and hypothermia protects the brain by interfering with these pathways.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2020년도 춘계학술대회
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• pp.86-86
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• 2020

The leaves of Staphylea bumalda (S. bumalda) as a deciduous tree distributed in Korea, China and Japan are used to treat respiratory diseases or inflammation. However, there is no scientific research on the immune-enhancing activity of S. bumalda leaves. Thus, in this study, we investigated the effect of water extracts from S. bumalda leaves (SBL) on the macrophage activity using mouse macrophage cells, RAW264.7. SBL increased production of immunomodulators such as NO, iNOS, IL-1β, IL-6, TNF-α and MCP-1 in RAW264.7 cells and activated phagocytic activity of RAW264.7 cells. Inhibition of TLR2 and TLR4 blocked SBL-mediated production of immunomodulators in RAW264.7 cells. In addition, SBL-mediated production of immunomodulators was attenuated by JNK inhibition in RAW264.7 cells. SBL increased JNK phosphorylation, while Inhibition of TLR2 and TLR4 blocked SBL-mediated JNK phosphorylation in RAW264.7 cells. These results are thought to be evidence that SBL activates JNK through stimulation of TLR2 and TLR4 in macrophage to induce the production of immunomodulators. In LPS-stimulated RAW264.7 cells, SBL inhibited over-production of immunomodulators. Summarizing the results, SBL showed immunostimulatory activity under normal conditions and immunosuppressive activity under LPS-induced excessive immune response conditions.

• Biomolecules & Therapeutics
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• 제31권1호
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• pp.73-81
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• 2023

Sirtuins (SIRTs) belong to the nicotinamide adenine dinucleotide (NAD+)-dependent class III histone deacetylase family. They are key regulators of cellular and physiological processes, such as cell survival, senescence, differentiation, DNA damage and stress response, cellular metabolism, and aging. SIRTs also influence carcinogenesis, making them potential targets for anticancer therapeutic strategies. In this study, we investigated the anticancer properties and underlying molecular mechanisms of a novel SIRT1 inhibitor, MHY2251, in human colorectal cancer (CRC) cells. MHY2251 reduced the viability of various human CRC cell lines, especially those with wild-type TP53. MHY2251 inhibited SIRT1 activity and SIRT1/2 protein expression, while promoting p53 acetylation, which is a target of SIRT1 in HCT116 cells. MHY2251 treatment triggered apoptosis in HCT116 cells. It increased the percentage of late apoptotic cells and the sub-G1 fraction (as detected by flow cytometric analysis) and induced DNA fragmentation. In addition, MHY2251 upregulated the expression of FasL and Fas, altered the ratio of Bax/Bcl-2, downregulated the levels of pro-caspase-8, -9, and -3 proteins, and induced subsequent poly(ADP-ribose) polymerase cleavage. The induction of apoptosis by MHY2251 was related to the activation of the caspase cascade, which was significantly attenuated by pre-treatment with Z-VAD-FMK, a pan-caspase inhibitor. Furthermore, MHY2251 stimulated the phosphorylation of c-Jun N-terminal kinase (JNK), and MHY2251-triggered apoptosis was blocked by pre-treatment with SP600125, a JNK inhibitor. This finding indicated the specific involvement of JNK in MHY2251-induced apoptosis. MHY2251 shows considerable potential as a therapeutic agent for targeting human CRC via the inhibition of SIRT1 and activation of JNK/p53 pathway.

• Biomolecules & Therapeutics
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• 제22권3호
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• pp.200-206
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• 2014

N-(p-Coumaryol) tryptamine (CT), a phenolic amide, has been reported to exhibit anti-oxidant and anti-inflammatory activities. However, the underlying mechanism by which CT exerts its pharmacological properties has not been clearly demonstrated. The objective of this study is to elucidate the anti-inflammatory mechanism of CT in lipopolysaccharide (LPS)-challenged RAW264.7 macrophage cells. CT significantly inhibited LPS-induced extracellular secretion of pro-inflammatory mediators such as nitric oxide (NO) and $PGE_2$, and protein expressions of iNOS and COX-2. In addition, CT significantly suppressed LPS-induced secretion of pro-inflammatory cytokines such as TNF-${\alpha}$ and IL-$1{\beta}$. To elucidate the underlying anti-inflammatory mechanism of CT, involvement of MAPK and Akt signaling pathways was examined. CT significantly attenuated LPS-induced activation of JNK/c-Jun, but not ERK and p38, in a concentration-dependent manner. Interestingly, CT appeared to suppress LPS-induced Akt phosphorylation. However, JNK inhibition, but not Akt inhibition, resulted in the suppression of LPS-induced responses, suggesting that JNK/c-Jun signaling pathway significantly contributes to LPS-induced inflammatory responses and that LPS-induced Akt phosphorylation might be a compensatory response to a stress condition. Taken together, the present study clearly demonstrates CT exerts anti-inflammatory activity through the suppression of JNK/c-Jun signaling pathway in LPS-challenged RAW264.7 macrophage cells.

• 생명과학회지
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• 제31권5호
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• pp.464-474
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• 2021

대사성질환, 암, 손상, 및 패혈증 등에 의해 유도되는 염증은 산화스트레스를 통해 세포의 미토콘드리아의 기능을 감퇴시켜 신경증과 근육위축증 등을 야기한다. 본 연구에서는 lipopolysaccharide (LPS)에 의해 유도된 미토콘 드리아의 기능감퇴와 근육위측증에 대한 butyrate의 억제효과를 확인하고자 하였다. LPS의 처리는 C2C12세포에서 MAPK의 활성을 통해 미토콘드리아 분열을 촉진하는 DRP1 (Ser616) 인산화와 Atrogin-1의 발현을 증가시켰다. 그러나 butyrate를 처리한 C2C12세포에서는 LPS 처리에 의한 염증 효과가 유의적으로 감소하며, 미토콘드리아 분열을 억제하는 DRP1 (Ser637)의 인산화와 mitofugin2 (Mfn2)의 발현을 증가를 유도하는 것을 확인하였다. 또한 butyrate를 처리한 세포에서 대사성질환을 유발하는 pyruvate dehydrogenase kinase 4 (PDK4)의 발현을 억제함이 관찰되었다. 이는 butyrate가 포도당 대사에서 염증에 의해 유도되는 Warburg 효과를 억제하여 산화스트레스를 개선함으로써, JNK의 활성을 억제하는 것으로 확인되었다. 이러한 결과들은 butyrate가 항산화효과를 통해 패혈증과 대사성질환과 같은 염증에 의해 유도되는 미토콘드리아의 기능 감퇴와 이에 따른 근육위축증을 개선할 수 있는 후보물질로 활용될 가능성이 있을 것으로 기대된다.

• 대한의생명과학회지
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• 제20권4호
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• pp.237-243
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• 2014

Triglyceride (TG) can cause death of macrophages and formation of foam cells thereby increasing inflammation in atherosclerotic plaques. Accumulation of cholesterol in macrophages is another critical event that promotes development of inflammatory cardiovascular diseases. Several proteins are known to transport intracellular cholesterol outside of the cell and these proteins are thought to be protective against atherosclerosis pathogenesis. It is unknown whether TG can affect cholesterol efflux in macrophages. In the current study, we examined mRNA expression levels of genes that promote efflux of cholesterol (ABCA1, ABCG1 and SR-B1). We found that TG treated THP-1 macrophages exhibited an increase in ABCG1 expression in a dose- and time-dependent manner. In contrast, the expression of ABCA1 and SR-B1 remained unchanged. To identify cell signaling pathways that participate in up-regulation of ABCG1, THP-1 macrophages were treated with various cell signaling inhibitors. We found that inhibition of the JNK and p38 MAPK pathway completely abrogated up-regulation of ABCG1 whereas inhibition of MEK1 further enhanced ABCG1 expression in TG treated THP-1 macrophages. Also, TG induced phosphorylation of JNK and p38 MAPK in THP-1 macrophages. These results suggest that TG may potentially influence cholesterol efflux in macrophages.

• Molecules and Cells
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• 제40권5호
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• pp.363-370
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• 2017

Extrahepatic cholangiocarcinoma (ECC), a malignant tumor of biliary origin, has a poor prognosis with limited treatment options. The KRAS oncogene is the most commonly mutated gene in ECC and one of the factors that predicts a poor prognosis and low survival rate. L1 cell adhesion molecule (L1CAM) is expressed in ECC cells and acts as an independent poor prognostic factor in predicting patient survival. In this study we investigate the functional significance of L1CAM in ECC cells with activating KRAS mutation. We selected an ECC cell line, EGI-1, with activating KRAS mutation, and then confirmed its expression of L1CAM by RT-PCR, western blot analysis, and flow cytometry. The suppression of L1CAM expression (using a specific lentivirus-delivered shRNA) significantly decreased the migratory and invasive properties of EGI-1 cells, without altering their proliferation or survival. Analyses of signaling effectors in L1CAM-depleted and control EGI-1 cells indicated that L1CAM suppression decreased the levels of both phosphorylated MKK4 and total MKK4, together with c-Jun N-terminal kinase (JNK) phosphorylation. Further, exposure to a JNK inhibitor (SP600125) decreased migration and invasion of EGI-1 cells. These results suggest that L1CAM promotes cellular migration and invasion via the induction of MKK4 expression, leading to JNK activation. Our study is the first to demonstrate a functional role for L1CAM in ECC carrying the activating KRAS mutation. Given that KRAS is the most commonly mutated oncogene in ECC, L1CAM may serve as an attractive therapeutic target for ECC cells with activating KRAS mutation.

• Parasites, Hosts and Diseases
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• 제44권3호
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• pp.197-207
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• 2006

This experiment focused on MAPK activation in host cell invasion and replication of T. gondii, as well as the expression of CC chemokines, MCP-1 and $MIP-1\alpha$, and enzyme, COX-2/prostaglandin $E_2(PGE_2)$ in infected cells via western blot, $[^3H]-uracil$ incorporation assay, ELISA and RT-PCR. The phosphorylation of ERK1/2 and p38 in infected HeLa cells was detected at 1 hr and/or 6 hr postinfection (PI). Tachyzoite proliferation was reduced by p38 or JNK MAPK inhibitors. MCP-1 secretion was enhanced in infected peritoneal macrophages at 6 hr PI. $MIP-1\alpha$ mRNA was increased in macrophages at 18 hr PI. MCP-1 and $MIP-1\alpha$ were reduced after treatment with inhibitors of ERK1/2 and JNK MAPKs. COX-2 mRNA gradually increased in infected RAW 264.7 cells and the secretion of COX-2 peaked at 6 hr PI. The inhibitor of JNK suppressed COX-2 expression. $PGE_2$ from infected RAW 264.7 cells was increased and synthesis was suppressed by PD98059, SB203580, and SP600125. In this study, the activation of p38, JNK and/or ERK1/2 MAPKs occurred during the invasion and proliferation of T. gondii tachyzoites in HeLa cells. Also, increased secretion and expression of MCP-1, $MIP-1\alpha$, COX-2 and $PGE_2$ were detected in infected macrophages, and appeared to occur via MAPK signaling pathways.

• 한국환경성돌연변이발암원학회:학술대회논문집
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• 한국환경성돌연변이발암원학회 2002년도 Molecular and Cellular Response to Toxic Substances
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• pp.144-144
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• 2002

• 한국자원식물학회지
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• 제36권4호
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• pp.257-263
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• 2023

본 연구에서 인가목 잎 추출물이 RAW264.7 세포에서 면역자 극인자의 생성을 증가시키고 포식작용의 활성화를 유도한다는 것을 확인하였다. 게다가 인가목 잎 추출물은 TLR4 의존적 JNK와 PI3K/AKT 신호전달 활성화를 통해 자가포식을 유도한다는 것을 확인하였다. 대식세포의 활성화와 자가포식은 선천면역반응과 후천면역반응을 향상시킬 수 있는 주요 전략 중 하나이기 때문에 인가목 잎 추출물은 인체의 면역반응을 증가시킬 수 있는 건강기능식품이나 보조제로 활용될 수 있을 것으로 생각된다. 그러나 본 연구에서는 작용기전을 구명하기 위해 관련된 단일억제제를 사용하였기 때문에 명확한 작용기전 구명을 위해 다양한 억제제 또는 siRNA를 활용한 추가적 연구가 필요하다고 판단된다.