• BMB Reports
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• 제49권8호
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• pp.437-442
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• 2016

We aimed to study the role of protein L-isoaspartyl methyltransferase (PIMT) in neuronal differentiation using basic fibroblast growth factor (bFGF)-induced neuronal differentiation, characterized by cell-body shrinkage, long neurite outgrowth, and expression of neuronal differentiation markers light and medium neurofilaments (NF). The bFGF-mediated neuronal differentiation of PC12 cells was induced through activation of mitogen-activated protein kinase (MAPK) signaling molecules [MAPK kinase 1/2 (MEK1/2), extracellular signal-regulated kinase 1/2 (ERK1/2), and p90RSK], and phosphatidylinositide 3-kinase (PI3K)/Akt signaling molecules PI3Kp110β, PI3Kp110γ, Akt, and mTOR. Inhibitors (adenosine dialdehyde and S-adenosylhomocysteine) of protein methylation suppressed bFGF-mediated neuronal differentiation of PC12 cells. PIMT-eficiency caused by PIMT-specific siRNA inhibited neuronal differentiation of PC12 cells by suppressing phosphorylation of MEK1/2 and ERK1/2 in the MAPK signaling pathway and Akt and mTOR in the PI3K/Akt signaling pathway. Therefore, these results suggested that PIMT was critical for bFGF-mediated neuronal differentiation of PC12 cells and regulated the MAPK and Akt signaling pathways.

• 한국해양바이오학회지
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• 제15권1호
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• pp.12-23
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• 2023

Sargassum horneri (SH), a brown macroalgae, has medicinal properties. The present study investigated the immune-enhancing effects of SH extract on peritoneal macrophages (PM). The SH significantly increased the production of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and nitric oxide (NO) in PM. It was confirmed that SH significantly increased NO expression through the increase of iNOS protein expression, which is the up-regulation pathway. Additionally, it was determined if SH activates the mitogen-activated protein kinase (MAPK) pathway, an upper regulatory mechanism that influences TNF-α, IL-6, and NO expression. Consequently, SH significantly increased the phosphorylation of p38, extracellular signal-regulated kinases (ERK), and c-Jun N-terminal kinase (JNK), all of which are MAPK pathway proteins. Moreover, the immune-enhancing effects of SH on another macrophage cell line, bone marrow-derived macrophages were investigated. It was observed that SH significantly enhanced TNF-α, IL-6, and NO production. Overall, this study demonstrates the immune-enhancing effects of SH on macrophages via activated MAPK pathway. Therefore, it suggests that SH has the potential to improve immunological activity in various macrophage cell lines and can be useful as an immune-enhancing treatment.

• Asian-Australasian Journal of Animal Sciences
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• 제27권5호
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• pp.733-742
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• 2014

The glucagon-like peptide 2 (GLP-2) that is expressed in intestine epithelial cells of mammals, is important for intestinal barrier function and regulation of tight junction (TJ) proteins. However, there is little known about the intracellular mechanisms of GLP-2 in the regulation of TJ proteins in piglets' intestinal epithelial cells. The purpose of this study is to test the hypothesis that GLP-2 regulates the expressions of TJ proteins in the mitogen-activated protein kinase (MAPK) signaling pathway in piglets' intestinal epithelial cells. The jejunal tissues were cultured in a Dulbecco's modified Eagle's medium/high glucose medium containing supplemental 0 to 100 nmol/L GLP-2. At 72 h after the treatment with the appropriate concentrations of GLP-2, the mRNA and protein expressions of zonula occludens-1 (ZO-1), occludin and claudin-1 were increased (p<0.05). U0126, an MAPK kinase inhibitor, prevented the mRNA and protein expressions of ZO-1, occludin, claudin-1 increase induced by GLP-2 (p<0.05). In conclusion, these results indicated that GLP-2 could improve the expression of TJ proteins in weaned pigs' jejunal epithelium, and the underlying mechanism may due to the MAPK signaling pathway.

• Molecules and Cells
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• 제42권4호
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• pp.363-375
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• 2019

Fungal sectorization is a complex trait that is still not fully understood. The unique phenotypic changes in sporadic sectorization in mutants of CpBck1, a mitogen-activated protein kinase kinase kinase (MAPKKK) gene, and CpSlt2, a mitogen-activated protein kinase (MAPK) gene, in the cell wall integrity pathway of the chestnut blight fungus Cryphonectria parasitica have been previously studied. Although several environmental and physiological factors cause this sectoring phenotype, genetic variants can also impact this complex morphogenesis. Therefore, RNA sequencing analysis was employed to identify candidate genes associated with sectorization traits and understand the genetic mechanism of this phenotype. Transcriptomic analysis of CpBck1 and CpSlt2 mutants and their sectored progeny strains revealed a number of differentially expressed genes (DEGs) related to various cellular processes. Approximately 70% of DEGs were common between the wild-type and each of CpBck1 and CpSlt2 mutants, indicating that CpBck1 and CpSlt2 are components of the same MAPK pathway, but each component governs specific sets of genes. Functional description of the DEGs between the parental mutants and their sectored progenies revealed several key pathways, including the biosynthesis of secondary metabolites, translation, amino acid metabolism, and carbohydrate metabolism; among these, pathways for secondary metabolism and translation appeared to be the most common pathway. The results of this comparative study provide a better understanding of the genetic regulation of sector formation and suggest that complex several regulatory pathways result in interplays between secondary metabolites and morphogenesis.

• BMB Reports
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• 제49권7호
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• pp.370-375
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• 2016

Ras oncoproteins are small molecular weight GTPases known for their involvement in oncogenesis, which operate in a complex signaling network with multiple effectors. Approximately 25% of human tumors possess mutations in a member of this family. The Raf1/MEK/Erk1/2 pathway is one of the most intensively studied signaling mechanisms. Different levels of regulation account for the inactivation of MAP kinases by MAPK phosphatases in a cell type- and stimuli-dependent manner. In the present study, using three inducible Ras-expressing NIH/3T3 cell lines, we demonstrated that MKP3 upregulation requires the activation of the Erk1/2 pathway, which correlates with the shutdown of this pathway. We also demonstrated, by applying pharmacological inhibitors and effector mutants of Ras, that induction of MKP3 at the protein level is positively regulated by the oncogenic Ras/Raf/MEK/Erk1/2 signaling pathway.

• International Journal of Oral Biology
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• 제45권4호
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• pp.169-178
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• 2020

L-ascorbic acid (L-AA; vitamin C) induces apoptosis in cancer cells. This study aimed to elucidate the molecular mechanisms of L-AA-induced apoptosis in human laryngeal epidermoid carcinoma Hep-2 cells. L-AA suppressed the viability of Hep-2 cells and induced apoptosis, as shown by the cleavage and condensation of nuclear chromatin and increased number of Annexin V-positive cells. L-AA decreased Bcl-2 protein expression but upregulated Bax protein levels. In addition, cytochrome c release from the mitochondria into the cytosol and activation of caspase-9, -8, and -3 were enhanced by L-AA treatment. Furthermore, apoptosis-inducing factor (AIF) and endonuclease G (EndoG) were translocated into the nucleus during apoptosis of L-AA-treated Hep-2 cells. L-AA effectively inhibited the constitutive nuclear factor-κB (NF-κB) activation and attenuated the nuclear expression of the p65 subunit of NF-κB. Interestingly, L-AA treatment of Hep-2 cells markedly activated Akt and mitogen-activated protein kinase (MAPK; extracellular signal-regulated kinase 1/2, p38, and c-Jun N-terminal kinase [JNK]) and and LY294002 (Akt inhibitor), SB203580 (p38 inhibitor) or SP600125 (a JNK inhibitor) decreased the levels of Annexin V-positive cells. These results suggested that L-AA induces the apoptosis of Hep-2 cells via the nuclear translocation of AIF and EndoG by modulating the Bcl-2 family and MAPK/Akt signaling pathways.

• BMB Reports
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• 제51권4호
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• pp.194-199
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• 2018

Mesenchymal stem cells (MSCs) have shown great potential in treating bone deficiency. Human adipose-derived stem cells (HASCs) are multipotent progenitor cells with multi-lineage differentiation potential. Human amnion-derived mesenchymal stem cells (HAMSCs) are capable of promoting osteogenic differentiation of MSCs. In this study, we investigated the effect of HAMSCs on HASCs by a transwell co-culture system. HAMSCs promoted proliferation, osteogenic differentiation, angiogenic potential and adiponectin (APN) secretion of HASCs. Moreover, the positive effect of HAMSCs was significantly inhibited by U0126, a highly selective inhibitor of extracellular signaling-regulated kinase 1/2 (ERK1/2) mitogen-activated protein kinase (MAPK) signaling pathway. These observations suggested that HAMSCs induced bone regeneration in HASCs via ERK1/2 MAPK signaling pathway.

• The Korean Journal of Physiology and Pharmacology
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• 제17권5호
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• pp.447-453
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• 2013

Osteoblastic activity of nectandrin A was examined in C2C12 cells. Nectandrin A enhances the BMP-induced osteoblastic differentiation and mineralization, manifested by the up-regulation of differentiation markers (alkaline phosphatase and osteogenic genes) and increased calcium contents. In C2C12 cells co-transfected with expression vector encoding Smad4 and Id1-Luc reporter, nectandrin A increased Id1 luciferase activity in a concentration-dependent manner, when compared to that in BMP-2 treated cells, indicating that Smad signaling pathway is associated with nectandrin A-enhanced osteoblastic differentiation in C2C12 cells. In addition, nectandrin A activated p38 mitogen-activated protein kinase (MAPK) in time- and concentration-dependent manners, and phosphorylated form of pSmad1/5/8 and alkaline phosphatase activity were both decreased when the cells were pretreated with SB203580, a p38 MAPK inhibitor, suggesting that p38 MAPK might be an upstream kinase for Smad signaling pathway. Taken together, nectandrin A enhances the BMP-induced osteoblastic differentiation and mineralization of C2C12 cells via activation of p38 MAPK-Smad signaling pathway, and it has a therapeutic potential for osteoporosis by promoting bone formation.

• Toxicological Research
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• 제28권1호
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• pp.19-24
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• 2012

In the present study, toxicity of silver nanoparticles (AgNPs) was investigated in the nematode, Caenohabditis elegans focusing on the upstream signaling pathway responsible for regulating oxidative stress, such as mitogen-activated protein kinase (MAPK) cascades. Formation of reactive oxygen species (ROS) was observed in AgNPs exposed C.elegans, suggesting oxidative stress as an important mechanism in the toxicity of AgNPs towards C. elegans. Expression of genes in MAPK signaling pathways increased by AgNPs exposure in less than 2-fold compared to the control in wildtype C.elegans, however, those were increased dramatically in sod-3 (gk235) mutant after 48 h exposure of AgNPs (i.e. 4-fold for jnk-1 and mpk-2; 6-fold for nsy-1, sek-1, and pmk-1, and 10-fold for jkk-1). These results on the expression of oxidative stress response genes suggest that sod-3 gene expression appears to be dependent on p38 MAPK activation. The high expressions of the pmk-1 gene 48 h exposure to AgNPs in the sod-3 (gk235) mutant can also be interpreted as compensatory mechanisms in the absence of important stress response genes. Overall results suggest that MAPK-based integrated stress signaling network seems to be involved in defense to AgNPs exposure in C.elegans.

• 생명과학회지
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• 제33권10호
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• pp.776-782
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• 2023

Silymarin은 간 보호, 항산화, 항염, 항암 등 다양한 생리 활성을 나타내는 것으로 보고되었고, 본 연구에서는 산화 스트레스에 대한 항산화 잠재력과 그 기전을 세포 생존력 및 활성산소종 생성 분석과 Western blot 분석을 통해 RAW 264.7 세포에서 알아보고자 하였다. Silymarin은 세포 독성 없이 lipopolysaccharide(LPS)에 의해 자극된 세포 내 활성산소종을 농도 의존적으로 소거하였다. 그리고 항산화 효과를 보여주는 것으로 알려진 제2상 효소 중 하나인 heme oxygenase (HO)-1의 발현은 silymarin 처리에 의해 강하게 유도되었다. 또한 silymarin 처리는 항산화 효소의 전사인자인 nuclear factor-erythroid 2 p45-related factor (Nrf)-2의 발현을 유의미하게 유도하였고, 이는 HO-1 발현증가와 일치하였다. 세포내 산화와 환원 항상성 조절과 관련된 신호 전달물질인 mitogen activated protein kinase (MAPK)와 phosphoinositde 3-kinase (PI3K)의 인산화 정도 또한 Western blot으로 분석하였고, 그 결과 silymarin 은 p38 MAPK 인산화에 의해 HO-1 발현을 유도하는 것으로 나타났다. 그리고 tert-butyl hydroperoxide (t-BHP)를 이용하여 세포내 지질 과산화를 유도함으로써 silymarin에 의해 유도된 HO-1의 항산화 효과를 확인하였다. 그 결과 silymarin 처리에 의해 세포사멸이 유의적으로 억제되었고, p38의 선택적 저해제를 처리한 세포군에서는 t-BHP에 의해 유의적인 세포사멸이 발생하였다. 이 결과를 통해 silymarin은 Nrf-2/p38 MAPK 신호 전달 경로를 통해 HO-1의 발현을 유도하고, 이를 통해 항산화 효과를 높이는 것을 확인할 수 있었다.