• Molecules and Cells
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• 제21권2호
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• pp.237-243
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• 2006

Brain-derived neurotrophic factor (BDNF) is a neuromodulator of nociceptive responses in the dorsal root ganglia (DRG) and spinal cord. BDNF synthesis increases in response to nerve growth factor (NGF) in trkA-expressing small and medium-sized DRG neurons after inflammation. Previously we demonstrated differential activation of multiple BDNF promoters in the DRG following peripheral nerve injury and inflammation. Using reporter constructs containing individual promoter regions, we investigated the effect of NGF on the multiple BDNF promoters, and the signaling pathway by which NGF activates these promoters in PC12 cells. Although all the promoters were activated 2.4-7.1-fold by NGF treatment, promoter IV gave the greatest induction. The p38 mitogen-activated protein kinase (MAPK) inhibitor, SB203580, phosphatidylinositol 3-kinase (PI-3K) inhibitor, LY294003, protein kinase A (PKA) inhibitor, H89, and protein kinase C (PKC) inhibitor, chelerythrine, had no effect on activation of promoter IV by NGF. However, activation was completely abolished by the MAPK kinase (MEK) inhibitors, U0126 and PD98059. In addition, these inhibitors blocked NGF-induced phosphorylation of extracellular signal-regulated protein kinase (ERK) 1/2. Taken together, these results suggest that the ERK1/2 pathway activates BDNF promoter IV in response to NGF independently of NGF-activated signaling pathways involving PKA and PKC.

• Molecules and Cells
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• 제41권5호
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• pp.436-443
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• 2018

The actin cytoskeleton plays a key role in the entry of mitosis as well as in cytokinesis. In a previous study, we showed that actin disruption delays mitotic entry at G2/M by sustained activation of extracellular signal-related kinase 1/2 (ERK1/2) in primary cells but not in transformed cancer cell lines. Here, we examined the mechanism of cell cycle delay at G2/M by actin dysfunction in IMR-90 normal human fibroblasts. We observed that de-polymerization of actin with cytochalasin D (CD) constitutively activated ribosomal S6 kinase (RSK) and induced inhibitory phosphorylation of Cdc2 (Tyr 15) in IMR-90 cells. In the presence of an actin defect in IMR-90 cells, activating phosphorylation of Wee1 kinase (Ser 642) and inhibitory phosphorylation of Cdc25C (Ser 216) was also maintained. However, when kinase-dead RSK (DN-RSK) was overexpressed, we observed sustained activation of ERK1/2, but no delay in the G2/M transition, demonstrating that RSK functions downstream of ERK in cell cycle delay by actin dysfunction. In DN-RSK overexpressing IMR-90 cells treated with CD, phosphorylation of Cdc25C (Ser 216) was blocked and phosphorylation of Cdc2 (Tyr 15) was decreased, but the phosphorylation of Wee1 (Ser 642) was maintained, demonstrating that RSK directly controls phosphorylation of Cdc25C (Ser 216), but not the activity of Wee1. These results strongly suggest that actin dysfunction in primary cells activates ERK1/2 to inhibit Cdc2, delaying the cell cycle at G2/M by activating downstream RSK, which phosphorylates and blocks Cdc25C, and by directly activating Wee1.

• 동의생리병리학회지
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• 제20권5호
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• pp.1315-1320
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• 2006

The root and rhizomes of Nardostachys chinensis belonging to the family Valerianaceae has been used for medicinal therapy in Korean traditional medicine. The parts have been especially used to elicit stomachic and sedative effects. Our previous studies reported that the water extract of N. chinensis has induced granulocytic differentiation inhuman promyelocytic leukemia (HL-60) cells. The Mitogen-activated protein kinases (MAPKs) are serine/threonine kinases involved in the regulation of various cellular responses, such as cell proliferation, differentiation and apoptosis. In this study, we investigated the signaling pathways on the HL-60 cell differentiation induced by N. chinensis. Activation of extracellular signal-regulated kinase (ERK) increased time-dependently in differentiation of HL-60 cells induced by N. chinersis. Activation of p38 increased slightly at 24 h after N. chinensis treatment, but activation of c-jun N-terminal kinase (JNK) was unaffected. Inhibitor of ERK (PD98059) significantly reduced NBT reduction activity induced by N. chinensis in HL-60 cells. In contrast, p38 inhibitor (SB203580) did not inhibit the cell differentiation. These results indicated that activaiton of ERK may De involved in HL-60 cell differentiation induced by N. chinensis.

• Animal cells and systems
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• 제16권3호
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• pp.190-197
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• 2012

Depression is one of the most prevalent diseases of alcohol abuse. Brain-derived neurotrophic factor (BDNF) plays a critical role in cell survival in the hippocampus. Phosphorylation of extracellular signal-regulated kinase 1/2 (p-ERK1/2) is induced by BDNF, and it regulates cell proliferation and differentiation in the brain. We investigated the effects of alcohol intake on depression-like behavior, cell proliferation, expressions of BDNF and its downstream molecules in the hippocampus using Mongolian gerbils. The gerbils were divided into four groups: control group, 0.5 g/kg alcohol-treated group, 1 g/kg alcohol-treated group, 2 g/kg alcohol-treated group. Each dose of alcohol was orally administered for 3 weeks. The present results demonstrated that alcohol intake induced depression-like behavior. Both 5-hydroxytryptamine synthesis and its synthesizing enzyme tryptophan hydroxylase expression in the dorsal raphe and cell proliferation in the hippocampal dentate gyrus were decreased by alcohol intake. Alcohol intake suppressed BDNF expression, and resulted in the decrease of its downstream molecules, pERK1/2 and Bcl-2, in the hippocampus. We showed that alcohol intake may lead to a depressed-like state with reduced hippocampal cell proliferation through inhibition of the BDNF-ERK signaling pathway.

• The Korean Journal of Physiology and Pharmacology
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• 제25권6호
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• pp.593-601
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• 2021

Primary cilia on kidney tubular cells play crucial roles in maintaining structure and physiological function. Emerging evidence indicates that the absence of primary cilia, and their length, are associated with kidney diseases. The length of primary cilia in kidney tubular epithelial cells depends, at least in part, on oxidative stress and extracellular signal-regulated kinase 1/2 (ERK) activation. Hydrogen sulfide (H₂S) is involved in antioxidant systems and the ERK signaling pathway. Therefore, in this study, we investigated the role of H₂S in primary cilia elongation and the downstream pathway. In cultured Madin-Darby Canine Kidney cells, the length of primary cilia gradually increased up to 4 days after the cells were grown to confluent monolayers. In addition, the expression of H₂S-producing enzyme increased concomitantly with primary cilia length. Treatment with NaHS, an exogenous H₂S donor, accelerated the elongation of primary cilia whereas DL-propargylglycine (a cystathionine γ-lyase inhibitor) and hydroxylamine (a cystathionine-β-synthase inhibitor) delayed their elongation. NaHS treatment increased ERK activation and Sec10 and Arl13b protein expression, both of which are involved in cilia formation and elongation. Treatment with U0126, an ERK inhibitor, delayed elongation of primary cilia and blocked the effect of NaHS-mediated primary cilia elongation and Sec10 and Arl13b upregulation. Finally, we also found that H₂S accelerated primary cilia elongation after ischemic kidney injury. These results indicate that H₂S lengthens primary cilia through ERK activation and a consequent increase in Sec10 and Arl13b expression, suggesting that H₂S and its downstream targets could be novel molecular targets for regulating primary cilia.

• Biomolecules & Therapeutics
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• 제29권1호
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• pp.90-97
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• 2021

Ultraviolet B (UVB) radiation causes DNA base modifications. One of these changes leads to the generation of 8-oxoguanine (8-oxoG) due to oxidative stress. In human skin, this modification may induce sunburn, inflammation, and aging and may ultimately result in cancer. We investigated whether phloroglucinol (1,3,5-trihydroxybenzene), by enhancing the expression and activity of 8-oxoG DNA glycosylase 1 (Ogg1), had an effect on the capacity of UVB-exposed human HaCaT keratinocytes to repair oxidative DNA damage. Here, the effects of phloroglucinol were investigated using a luciferase activity assay, reverse transcription-polymerase chain reactions, western blot analysis, and a chromatin immunoprecipitation assay. Phloroglucinol restored Ogg1 activity and decreased the formation of 8-oxoG in UVB-exposed cells. Moreover, phloroglucinol increased Ogg1 transcription and protein expression, counteracting the UVB-induced reduction in Ogg1 levels. Phloroglucinol also enhanced the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) as well as Nrf2 binding to an antioxidant response element located in the Ogg1 gene promoter. UVB exposure inhibited the phosphorylation of protein kinase B (PKB or Akt) and extracellular signal-regulated kinase (Erk), two major enzymes involved in cell protection against oxidative stress, regulating the activity of Nrf2. Akt and Erk phosphorylation was restored by phloroglucinol in the UVB-exposed keratinocytes. These results indicated that phloroglucinol attenuated UVB-induced 8-oxoG formation in keratinocytes via an Akt/Erk-dependent, Nrf2/Ogg1-mediated signaling pathway.

• The Korean Journal of Pain
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• 제34권1호
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• pp.19-26
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• 2021

Background: Prolotherapy is a proliferation therapy as an alternative medicine. A combination of dextrose solution and lidocaine is usually used in prolotherapy. The concentrations of dextrose and lidocaine used in the clinical field are very high (dextrose 10%-25%, lidocaine 0.075%-1%). Several studies show about 1% dextrose and more than 0.2% lidocaine induced cell death in various cell types. We investigated the effects of low concentrations of dextrose and lidocaine in fibroblasts and suggest the optimal range of concentrations of dextrose and lidocaine in prolotherapy. Methods: Various concentrations of dextrose and lidocaine were treated in NIH-3T3. Viability was examined with trypan blue exclusion assay and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Migration assay was performed for measuring the motile activity. Extracellular signal-regulated kinase (Erk) activation and protein expression of collagen I and α-smooth muscle actin (α-SMA) were determined with western blot analysis. Results: The cell viability was decreased in concentrations of more than 5% dextrose and 0.1% lidocaine. However, in the concentrations 1% dextrose (D1) and 0.01% lidocaine (L0.01), fibroblasts proliferated mildly. The ability of migration in fibroblast was increased in the D1, L0.01, and D1 + L0.01 groups sequentially. D1 and L0.01 increased Erk activation and the expression of collagen I and α-SMA and D1 + L0.01 further increased. The inhibition of Erk activation suppressed fibroblast proliferation and the synthesis of collagen I. Conclusions: D1, L0.01, and the combination of D1 and L0.01 induced fibroblast proliferation and increased collagen I synthesis via Erk activation.

• Journal of Yeungnam Medical Science
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• 제37권4호
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• pp.269-276
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• 2020

Fibrosis is characterized by excessive accumulation of extracellular matrix components. The fibrotic process ultimately leads to organ dysfunction and failure in chronic inflammatory and metabolic diseases such as pulmonary fibrosis, advanced kidney disease, and liver cirrhosis. Idiopathic pulmonary fibrosis (IPF) is a common form of progressive and chronic interstitial lung disease of unknown etiology. Pathophysiologically, the parenchyma of the lung alveoli, interstitium, and capillary endothelium becomes scarred and stiff, which makes breathing difficult because the lungs have to work harder to transfer oxygen and carbon dioxide between the alveolar space and bloodstream. The transforming growth factor beta (TGF-β) signaling pathway plays an important role in the pathogenesis of pulmonary fibrosis and scarring of the lung tissue. Recent clinical trials focused on the development of pharmacological agents that either directly or indirectly target kinases for the treatment of IPF. Therefore, to develop therapeutic targets for pulmonary fibrosis, it is essential to understand the key factors involved in the pathogenesis of pulmonary fibrosis and the underlying signaling pathway. The objective of this review is to discuss the role of kinase signaling cascades in the regulation of either TGF-β-dependent or other signaling pathways, including Rho-associated coiled-coil kinase, c-jun N-terminal kinase, extracellular signal-regulated kinase 5, and p90 ribosomal S6 kinase pathways, and potential therapeutic targets in IPF.

• The Korean Journal of Physiology and Pharmacology
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• 제15권4호
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• pp.245-249
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• 2011

Amphetamine, a synthetic psychostimulant, is transported by the dopamine transporter (DAT) to the cytosol and increases the exchange of extracellular amphetamine by intracellular dopamine. Recently, we reported that the phosphorylation levels of ezrin-radixin-moesin (ERM) proteins are regulated by psychostimulant drugs in the nucleus accumbens, a brain area important for drug addiction. However, the significance of ERM proteins phosphorylation in response to drugs of abuse has not been fully investigated. In this study, using PC12 cells as an in vitro cell model, we showed that amphetamine increases ERM proteins phosphorylation and protein kinase C (PKC) ${\beta}$ inhibitor, but not extracellular signal-regulated kinase (ERK) or phosphatidylinositol 3-kinases (PI3K) inhibitors, abolished this effect. Further, we observed that DAT inhibitor suppressed amphetamine-induced ERM proteins phosphorylation in PC12 cells. These results suggest that $PKC{\beta}$-induced DAT regulation may be involved in amphetmaine-induced ERM proteins phosphorylation.

• Macromolecular Research
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• 제15권4호
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• pp.370-378
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• 2007

Mechanical stimulation is known to activate several cellular signal transduction pathways, leading to the induction of signaling molecules and extracellular matrix (ECM) proteins, thereby modulating cellular activities, such as proliferation and survival. In this study, primary human dermal fibroblasts (HDFs) were seeded onto chitosan-based scaffolds, and then cultured for 3 weeks in a bioreactor under a cyclic strain of 1 Hz frequency. Compared to control samples cultured under static conditions, the application of a cyclic strain stimulated the proliferation of HDFs in I week, and by week 3 the thickness of the cell/scaffold composites increased 1.56 fold. Moreover, immunohistochemical staining of the culture media obtained from the cell/scaffold samples subjected to the cyclic strain, revealed increases in the expression and secretion of ECM proteins, such as fibronectin and collagen. These results suggest that the preconditioning of cell/scaffold composites with a cyclic strain may enhance the proliferation of HDFs, and even facilitate integration of the engineered artificial dermal tissue into the host graft site.