• Biomedical Science Letters
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• v.2 no.2
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• pp.175-185
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• 1996

The mitogen-activated protein(MAP) kinase signal transduction pathway represents an important mechanism by which mitogen, such as serum and PMA, regulate cell proliferation and differentiation. Target substrates of the MAP kinase are located within several compartments containing plasma membranes and nucleus. We now report that serum addition induces proliferation of the P388 murine leukemia cell, but PMA does not, while both serum and PMA treatment cause translocation of the MAP kinase, mainly p42$^{mapk}$ isoform, from cytosol into the nucleus, which was monitored by immunoblot analysis using polyclonal anti-ERK1 antibodies. We investigated whether the MAP kinase was capable of phosphorylating c-Jun protein and GST-fusion proteins, the P562$^{kk}$N-terminal peptides (1-77 or 1-123 domain) of the T cell tyrosine kinase, using the partially purified MAP kinase by SP-sephadex C-50, phenyl superose and Mono Q column chromatography. We found that the partially purified MAP kinase was able to phosphorylate c-Jun protein and the GST-fusion protein expressed using E.coli DH5$\alpha$ which is transformed with pGEX-3Xb plasmid vector carrying of p562$^{kk}$N-terminal peptide-encoding DNA. These results imply that tyrosine kinase receptor/Ras/Raf/MAP kinase pathway is a major mechanism for mitogen-induced cell proliferation in P388 murine leukemia cell and that the various MAP kinase isoforms may have their own target substrates located in distinct subcellular compartments.

• Journal of Life Science
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• v.26 no.1
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• pp.101-108
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• 2016

The aim of this study was to evaluate the relationships between the expression of Heat shock protein70 (HSP70), Raf-1 and Bcl-2-associated athanogene-1 (BAG1) protein in diffuse type gastric carcinoma and examine association of HSP70, Raf-1 and BAG1 expression with various clinic-pathological factors and survival. Heat shock protein70 is induced in the cells in response to various stress conditions, including carcinogens. Overexpression of heat shock protein 70 has been observed in many types of cancer. The proto-oncoprotein Raf is pivotal for mitogen-activated protein kinase (MAPK) signaling, and its aberrant activation has been implicated in multiple human cancers. Overexpression of BAG1 protein has been documented in some type of human cancer. BAG1 has been reported to interact with protein involved with a variety of signal pathway, and regulation of cell differentiation, survival and apoptosis. These interaction partners include HSP70 and Raf-1. The percentage of tumors exhibiting HSP70 positivity was significantly in cases of positive lymph node metastasis (64.9%) compared to cases without lymph node metastasis (35.1%, p=0.007). HS70 expression was correlated with pathological N-stage (p=0.006). Expression of BAG1 was detected in the majority of diffuse type gastric carcinoma tissues (71.7%), especially in younger patients (80% vs 52.6%, p=0.035). Furthermore BAG1 expression was correlated with tumor size (p=0.020). Raf-1 expression was found to be significantly associated with tumor size (p=0.005). The result indicate that HSP70 was significantly correlated the progression of diffuse type gastric cancer. Expression of BAG1 and Raf-1 may be used as diagnostic markers for gastric carcinoma.

• Molecules and Cells
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• v.24 no.1
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• pp.95-104
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• 2007

The mechanism of acacetin-induced apoptosis of human breast cancer MCF-7 cells was investigated. Acacetin caused 50% growth inhibition ($IC_{50}$) of MCF-7 cells at $26.4{\pm}0.7{\mu}M$ over 24 h in the MTT assay. Apoptosis was characterized by DNA fragmentation and an increase of sub-G1 cells and involved activation of caspase-7 and PARP (poly-ADP-ribose polymerase). Maximum caspase 7 activity was observed with $100{\mu}M$ acacetin for 24 h. Caspase 8 and 9 activation cascades mediated the activation of caspase 7. Acacetin caused a reduction of Bcl-2 expression leading to an increase of the Bax:Bcl-2 ratio. It also caused a loss of mitochondrial membrane potential that induced release of cytochrome c and apoptosis inducing factor (AIF) into the cytoplasm, enhancing ROS generation and subsequently resulting in apoptosis. Pretreatment of cells with N-acetylcysteine (NAC) reduced ROS generation and cell growth inhibition, and pretreatment with NAC or a caspase 8 inhibitor (Z-IETD-FMK) inhibited the acacetin-induced loss of mitochondrial membrane potential and release of cytochrome c and AIF. Stress-activated protein kinase/c-Jun $NH_4$-terminal kinase 1/2 (SAPK/JNK1/2) and c-Jun were activated by acacetin but extracellular-regulated kinase 1/2 (Erk1/2) nor p38 mitogen-activated protein kinase (MAPK) were not. Our results show that acacetin-induced apoptosis of MCF-7 cells is mediated by caspase activation cascades, ROS generation, mitochondria-mediated cell death signaling and the SAPK/JNK1/2-c-Jun signaling pathway, activated by acacetin-induced ROS generation.

• Journal of Korean Physical Therapy Science
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• v.13 no.2
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• pp.129-135
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• 2006

Vascular smooth muscle contraction is mediated by activation of extracellular signal-regulated kinase (ERK) 1/2, an isoform of mitogen-activated protein kinase (MAPK). However, the role of stress-activated protein kinase/c-Jun N-terminal kinase (JNK) in vascular smooth muscle contraction has not been defined. We investigated the role of JNK in the contractile response to norepinephrine (NE) in rat aortic smooth muscle. NE evoked contraction in a dose-dependent manner, and this effect was inhibited by the JNK inhibitor SP600125. NE increased the phosphorylation of JNK, which was greater in aortic smooth muscle from hypertensive rats than from normotensive rats. NE-induced JNK phosphorylation was significantly inhibited by SP600125 and the conventional-type PKC (cPKC) inhibitor Go6976, but not by the Rho kinase inhibitor Y27632 or the phosphatidylinositol 3-kinase inhibitor LY294002. Thymeleatoxin, a selective activator of cPKC, increased JNK phosphorylation, which was inhibited by $G{\ddot{o}}6976$. SP600125 attenuated the phosphorylation of caldesmon, an actin-binding protein whose phosphorylation is increased by NE. These results show that JNK contributes to NE-mediated contraction through phosphorylation of caldesmon in rat aortic smooth muscle, and that this effect is regulated by the PKC pathway, especially cPKC.

• Korean Journal of Food Science and Technology
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• v.53 no.6
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• pp.722-730
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• 2021

In this study, we aimed to elucidate the intracellular signaling pathways for macrophage activation by the polysaccharide GBW-II purified from ginseng berry. GBW-II consists of 14 different sugars, including rarely observed sugars such as 2-O-methyl-xylose, apiose, aceric acid, 2-keto-3-deoxy-D-manno-2-octulosonic acid, and 2-keto-3-deoxy-D-lyxo-2-heptulosaric acid, which are typical RG-II component sugars. GBW-II enhanced the production of IL-6 and TNF-α in RAW 264.7 cells. In experiments evaluating specific inhibitor activity, it was found that the production of IL-6 was suppressed by inhibitors of SB, PD, and BAY, and the production of TNF-α was suppressed by PD and BAY. The experiments with neutralizing antibodies showed that TLR4 was involved in the stimulation of IL-6 production by GBW-II in RAW 264.7 cells, whereas TNF-α production was regulated through SR and TLR2. These results suggest that GBW-II activates the MAPK and NF-κB pathways via several macrophage receptors, including SR, TLR2, and TLR4, and subsequently induces the secretion of IL-6 and TNF-α.

• Journal of Life Science
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• v.33 no.5
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• pp.414-421
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• 2023

Cnidium japonicum (C. japonicum) is a type of halophyte that inhabits soil of a high salinity, and according to previous studies, it is known to have antitumor effects. However, the skin's protective effect, particularly against UVB irradiation, has not been revealed. In this study, C. japonicum crude extract was studied to determine its effect on damage to human keratinocytes (HaCaT) induced by UVB irradiation, and ROS assays were performed, the results of which showed that C. japonicum crude extract affects UVB-induced photoaging damage in human keratinocytes. To examine inhibitory effects against the expressions of MMPs, RT-PCR and Western blot assay were performed by treating the crude extract at concentrations of 10, 50, and 100 ㎍/ml by irradiating UVB at 15 mJ/cm². As a result, it was confirmed that the mRNA and protein expression levels of MMP-1, MMP-3, and MMP-9 decreased in the group treated with C. japonicum crude extract, which also effectively regulated the antioxidant defense mechanism pathway by activating JNK, ERK, and p38. In conclusion, the current study suggested the possibility that C. japonicum could be used as a raw material for anti-photoaging cosmeceuticals in the future.

• Journal of Life Science
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• v.30 no.11
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• pp.983-989
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• 2020

The balance between bone-resorbing osteoclasts and bone-forming osteoblasts is key to bone health. An imbalance between osteoclasts and osteoblasts leads to various bone-related disorders, such as osteoporosis, osteomalacia, and osteopetrosis. However, the bone-resorption inhibitor drugs that are currently used may cause side effects. Natural substances have recently received much attention as therapeutic drugs for the treatment of bone health. This study was designed to determine the effect of Tenebrio molitor larvae ethanol extract (TME) on receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation. To measure the effect of TME on osteoclast differentiation, RAW264.7 cells were treated with RANKL with or without TME for 5 days. The tartrate-resistant acid phosphatase (TRAP) activity was significantly inhibited by treatment of TME without cytotoxicity up to 2 mg/ml. In addition, TME effectively suppressed expression of osteoclast differentiation-related marker genes and proteins such as TRAP, NFATc1, and c-Src. TME also significantly inhibited the p38 mitogen-activated protein kinase (MAPK) signaling pathway without affecting ERK and JNK signaling in RANKL-induced RAW264.7 cells. Consequently, we conclude that TME suppresses osteoclast differentiation by inhibiting RANKL-induced osteoclastogenic genes expression through the p38 MAPK signaling pathways. These results suggest that TME and its bioactive components are potential therapeutics for bone-related diseases such as osteoporosis.