• Journal of Microbiology and Biotechnology
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• 제21권9호
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• pp.903-913
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• 2011

Vibrio parahaemolyticus, which causes gastroenteritis, wound infection, and septicemia, has two sets of type III secretion systems (TTSS), TTSS1 and TTSS2. A TTSS1-deficient vcrD1 mutant of V. parahaemolyticus showed an attenuated cytotoxicity against HEp-2 cells, and a significant reduction in mouse lethality, which were both restored by complementation with the intact vcrD1 gene. V. parahaemolyticus also triggered phosphorylation of mitogen-activated protein kinases (MAPKs) including p38 and ERK1/2 in HEp-2 cells. The ability to activate p38 and ERK1/2 was significantly affected in a TTSS1-deficient vcrD1 mutant. Experiments using MAPK inhibitors showed that p38 and ERK1/2 MAPKs are involved in V. parahaemolyticus-induced death of HEp-2 cells. In addition, caspase-3 and caspase-9 were processed into active forms in V. parahaemolyticus-exposed HEp-2 cells, but activation of caspases was not essential for V. parahaemolyticus-induced death of HEp-2 cells, as shown by both annexin V staining and lactate dehydrogenase release assays. We conclude that secreted protein(s) of TTSS1 play an important role in activation of p38 and ERK1/2 in HEp-2 cells that eventually leads to cell death via a caspase-independent mechanism.

• Parasites, Hosts and Diseases
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• 제54권6호
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• pp.759-768
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• 2016

Cystic echinococcosis (CE) treatment urgently requires a novel drug. The p38 mitogen-activated protein kinases (MAPKs) are a family of Ser/Thr protein kinases, but still have to be characterized in Echinococcus granulosus. We identified a 1,107 bp cDNA encoding a 368 amino acid MAPK protein (Egp38) in E. granulosus. Egp38 exhibits 2 distinguishing features of p38-like kinases: a highly conserved T-X-Y motif and an activation loop segment. Structural homology modeling indicated a conserved structure among Egp38, EmMPK2, and H. sapiens $p38{\alpha}$, implying a common binding mechanism for the ligand domain and downstream signal transduction processing similar to that described for $p38{\alpha}$. Egp38 and its phosphorylated form are expressed in the E. granulosus larval stages vesicle and protoscolices during intermediate host infection of an intermediate host. Treatment of in vitro cultivated protoscolices with the p38-MAPK inhibitor ML3403 effectively suppressed Egp38 activity and led to significant protoscolices death within 5 days. Treatment of in vitro-cultivated protoscolices with $TGF-{\beta}1$ effectively induced Egp38 phosphorylation. In summary, the MAPK, Egp38, was identified in E. granulosus, as an anti-CE drug target and participates in the interplay between the host and E. granulosus via human $TGF-{\beta}1$.

• Journal of Preventive Medicine and Public Health
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• 제48권3호
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• pp.132-141
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• 2015

Objectives: With recent advances in nanoparticle manufacturing and applications, potential exposure to nanoparticles in various settings is becoming increasing likely. No investigation has yet been performed to assess whether respiratory tract exposure to cerium oxide ($CeO_2$) nanoparticles is associated with alterations in protein signaling, inflammation, and apoptosis in rat lungs. Methods: Specific-pathogen-free male Sprague-Dawley rats were instilled with either vehicle (saline) or $CeO_2$ nanoparticles at a dosage of 7.0 mg/kg and euthanized 1, 3, 14, 28, 56, or 90 days after exposure. Lung tissues were collected and evaluated for the expression of proteins associated with inflammation and cellular apoptosis. Results: No change in lung weight was detected over the course of the study; however, cerium accumulation in the lungs, gross histological changes, an increased Bax to Bcl-2 ratio, elevated cleaved caspase-3 protein levels, increased phosphorylation of p38 MAPK, and diminished phosphorylation of ERK-1/2-MAPK were detected after $CeO_2$ instillation (p<0.05). Conclusions: Taken together, these data suggest that high-dose respiratory exposure to $CeO_2$ nanoparticles is associated with lung inflammation, the activation of signaling protein kinases, and cellular apoptosis, which may be indicative of a long-term localized inflammatory response.

• Clinical and Experimental Pediatrics
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• 제60권6호
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• pp.181-188
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• 2017

Purpose: Hypoxic-ischemic encephalopathy is a significant cause of neonatal morbidity and mortality. Erythropoietin (EPO) is emerging as a therapeutic candidate for neuroprotection. Therefore, this study was designed to determine the neuroprotective role of recombinant human EPO (rHuEPO) and the possible mechanisms by which mitogen-activated protein kinase (MAPK) signaling pathway including extracellular signal-regulated kinase (ERK1/2), JNK, and p38 MAPK is modulated in cultured cortical neuronal cells and astrocytes. Methods: Primary neuronal cells and astrocytes were prepared from cortices of ICR mouse embryos and divided into the normoxic, hypoxia (H), and hypoxia-pretreated with EPO (H+EPO) groups. The phosphorylation of MAPK pathway was quantified using western blot, and the apoptosis was assessed by caspase-3 measurement and terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Results: All MAPK pathway signals were activated by hypoxia in the neuronal cells and astrocytes (P<0.05). In the neuronal cells, phosphorylation of ERK-1/-2 and apoptosis were significantly decreased in the H+EPO group at 15 hours after hypoxia (P<0.05). In the astrocytes, phosphorylation of ERK-1/-2, p38 MAPK, and apoptosis was reduced in the H+EPO group at 15 hours after hypoxia (P<0.05). Conclusion: Pretreatment with rHuEPO exerts neuroprotective effects against hypoxic injury reducing apoptosis by caspase-dependent mechanisms. Pathologic, persistent ERK activation after hypoxic injury may be attenuateed by pretreatment with EPO supporting that EPO may regulate apoptosis by affecting ERK pathways.

• Archives of Pharmacal Research
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• 제23권6호
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• pp.605-612
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• 2000

Green tea polyphenols (GTP) have been demonstrated to suppress tumorigenesis in several chemical-induced animal carcinogenesis models, and predicted as promising chemopreventive agents in human. Recent studies of GTP extracts showed the involvement of mitogen-activated protein kinases (MAPKs) in the regulation of Phase II enzymes gene expression and induction of apoptosis. In the current work we compared the biological actions of five green tea catechins: (1) induction of ARE reporter gene, (2) activation of MAP kinases, (3) cytotoxicity in human hepatoma HepG2-C8 cells, and (4) caspase activation in human cervical squamous carcinoma HeLa cells. For the induction of phase IIgene assay, (-)-epigallocatechin-3-gallate (EGCG) and (-)-epicatechin-3-gallate (ECG) potently induced antioxidant response element (ARE)-mediated luciferase activity, with induction observed at 25 $\mu\textrm{m}$with EGCG. The induction of ARE reporter gene appears to be structurally related to the 3-gallate group. Comparing the activation of MAPK by the five polyphenols, only EGCG showed potent activation of all three MAPKs (ERK, JNK and p38) in a dose- and time-dependent manner, whereas EGC activated ERK and p38. In the concentration range of 25 $\mu\textrm{m}$ to 1 mM, EGCG and ECG strongly suppressed HepG2-ARE-C8 cell-growth. To elucidate the mechanisms of green tea polyphenol-induced apoptosis, we measured the activation of an important cell death protein, caspase-3 induced by EGCG, and found that caspase-3 was activated in a dose- and time-dependent manner. Interestingly, the activation of caspase-3 was a relatively late event (peaked at 16 h), whereas activation of MAPKs was much earlier (peaked at 2 h). It is possible, that at low concentrations of EGCG, activation of MAPK leads to ARE-mediated gene expression including phase II detoxifying enzymes. Whereas at higher concentrations of EGCG, sustained activation of MAPKs such as JNK leads to apoptosis. These mechanisms are currently under investigation in our laboratory. As the most abundant catechin in GTP extract, we found that EGCG potently induced ARE-mediated gene expression, activated MAP kinase pathway, stimulated caspase-3 activity, and induced apoptosis. These mechanisms together with others, may contribute to the overall chemopreventive function of EGCG itself as well as the GTP.

• 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.

• Tuberculosis and Respiratory Diseases
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• 제72권3호
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• pp.275-283
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• 2012

Background: Healthy individuals who develop nontuberculous mycobacteria (NTM) lung disease are likely to have specific susceptibility factors which can lead to a NTM infection. The aim of the present study was to investigate the mechanism underlying innate immune responses, including the role of mitogen-activated protein kinase (MAPK), in Mycobacterium abscessus lung disease. Methods: Extracellular signal-regulated kinase (ERK1/2) and p38 MAPK expression in monocytes from peripheral blood mononuclear cells were measured by Western blot analysis after stimulation by Mycobacterium avium in five patients with M. abscessus lung disease and seven healthy controls. A M. avium-induced cytokine assay was performed after inhibition of ERK1/2 and p38 MAPK pathways. Results: Mycobacterium avium induced p38 and ERK1/2 expression in monocytes from healthy controls and subsequently upregulated tumor necrosis factor (TNF)-${\alpha}$, interleukin (IL)-6, and IL-10 production. In monocytes from patients with M. abscessus lung disease, however, induction of p38 and ERK1/2 expression, and the production of TNF-${\alpha}$, IL-6, and IL-10 were significantly lower. Conclusion: Decreased activity of MAPK and cytokine secretion in monocytes from patients with M. abscessus lung disease may provide an explanation regarding host susceptibility to these uncommon infections.

• Journal of Ginseng Research
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• 제43권2호
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• pp.236-241
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• 2019

Background: Thromboxane A2 ($TXA_2$) induces platelet aggregation and promotes thrombus formation. Although ginsenoside Ro (G-Ro) from Panax ginseng is known to exhibit a $Ca^{2+}-antagonistic$ antiplatelet effect, whether it inhibits $Ca^{2+}-dependent$ cytosolic phospholipase $A_2$ ($cPLA_{2{\alpha}}$) activity to prevent the release of arachidonic acid (AA), a $TXA_2$ precursor, is unknown. In this study, we attempted to identify the mechanism underlying G-Ro-mediated $TXA_2$ inhibition. Methods: We investigated whether G-Ro attenuates $TXA_2$ production and its associated molecules, such as cyclooxygenase-1 (COX-1), $TXA_2$ synthase (TXAS), $cPLA_{2{\alpha}}$, mitogen-activated protein kinases, and AA. To assay COX-1 and TXAS, we used microsomal fraction of platelets. Results: G-Ro reduced $TXA_2$ production by inhibiting AA release. It acted by decreasing the phosphorylation of $cPLA_{2{\alpha}}$, p38-mitogen-activated protein kinase, and c-Jun N-terminal kinase1, rather than by inhibiting COX-1 and TXAS in thrombin-activated human platelets. Conclusion: G-Ro inhibits AA release to attenuate $TXA_2$ production, which may counteract $TXA_2-associated$ thrombosis.

• 동의생리병리학회지
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• 제22권6호
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• pp.1572-1578
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• 2008

In previous report, Seungmagalgeun-tang (SGT) could exert its anti-inflammatory actions in the BV-2 microglial cells. However, study on the anti-inflammatory effect of SGT in mast cells has not been identified. Therefore, we examined on the anti-inflammatory effect of SGT on the phorbol 12-myristate 13-acetate (PMA) and calcium ionophore A23187-induced rat basophilic leukemia (RBL-2H3) cells. SGT inhibited the release of ${\beta}$-hexosaminidase and secretion and expression of pro-inflammatory cytokines such as tumor necrosis factor (TNF)-${\alpha}$ and interleukin (IL)-4 on RBL-2H3 cells, without affecting cell viability. The protein expression level of nuclear factor (NF)-${\kappa}B$ (p65) was decreased in the nucleus by SGT. In addition, SGT suppressed the degradation of inhibitory protein $I{\kappa}B-{\alpha}$ protein, the activation of p38 mitogen-activated protein kinase (MAPK), and the expressions of cyclooxygenase (COX)-2 mRNA and protein level in RBL-2H3 cells. These results suggest that SGT could be involved anti-allergic effect by control of NF-${\kappa}B$ (p65) translocation into the nucleus through inhibition of $I{\kappa}B-{\alpha}$ degradation and suppression of COX-2 expression.

• 대한본초학회지
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• 제22권1호
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• pp.111-117
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• 2007

Objectives : The purpose of this study was to investigate the anti-inflammatory effects of extract from Pulsatilla koreana $N_{AKAI}$ (PK) on the peritoneal macrophage. Methods : To evaluate of anti-inflammatory of PK, we examined cytokines and NO production in lipopolysacchride (LPS)-induced macrophages. Furthermore, we examined molecular mechanism using western blot. Results : 1.Extract from PK reduced LPS-induced NO, tumor necrosis factor-a ($TNF-{\alpha}$), interleukin (IL)-6 and IL-12 production in peritoneal macrophages. 2.Extract from PK itself does not have any cytotoxic effect. PK inhibited the activation of extracelluar signal-regulated kinase(ERK 1/2) but not another mitogen-activated protein kinases (MAPKs) such as p38, c-Jun NH2-terminal kinase (JNK) and the degradation of inhibitory kappa B a ($I_{k}B_{a}$) does not any effect in the LPS-stimulated peritoneal macrophages. Conclusion : PK down-regulated LPS-induced NO and cytokines production, which may be provide a clinical basis for anti-inflammatory properties of PK.