• Korean Journal of Plant Tissue Culture
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• v.27 no.5
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• pp.375-377
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• 2000

It is now generally accepted that a phosphoinositide cycle is involved in the transduction of a variety of signals in plant cells. In animal cells, the hydrolysis of phosphatidyl-4,5-bisphosphate catalysed by phosphatidylinositol - specific phospholipase C yields to D-myo-inositol - 1,4,5-trisphosphate and diacylglycerol, which are well known second messengers. The binding of InsP$_3$to a receptor located on the endoplasmic reticulum triggers a calcium release from the endoplasmic reticulum. We have detected and partially characterised key components of phosphoinositide signaling. First, tobacco microsomal fraction and plasma membrane PI-PLC. Consecutively, using a radioligand binding assay we have identified a $Ca^{2+}$ -dependent high affinity InsP$_3$binding site in microsomal membrane fraction vesicle preparation and then we have measured inositol-1,4,5-trisphosphate induced calcium release from tobacco microsomal fraction. These findings suggest that phosphoinositide signaling system is present and operates in the tobacco suspension culture.e.

• Biomolecules & Therapeutics
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• v.31 no.6
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• pp.682-691
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• 2023

Cell transformation induced by epidermal growth factor (EGF) and 12-O-tetradecanoylphorbol-13-acetate (TPA) is a critical event in cancer initiation and progression, and understanding the underlying mechanisms is essential for the development of new therapeutic strategies. Licorice extract contains various bioactive compounds, which have been reported to have anticancer and anti-inflammatory effects. This study investigated the cancer preventive efficacy of licochalcone D (LicoD), a chalcone derivative in licorice extract, in EGF and TPA-induced transformed skin keratinocyte cells. LicoD effectively suppressed EGF-induced cell proliferation and anchorage-independent colony growth. EGF and TPA promoted the S phase of cell cycle, while LicoD treatment caused G1 phase arrest and down-regulated cyclin D1 and up-regulated p21 expression associated with the G1 phase. LicoD also induced apoptosis and increased apoptosis-related proteins such as cleaved-caspase-3, cleaved-caspase-7, and Bax (Bcl2-associated X protein). We further investigated the effect of LicoD on the AKT signaling pathway involved in various cellular processes and found decreased p-AKT, p-GSK3β, and p-NFκB expression. Treatment with MK-2206, an AKT pharmacological inhibitor, suppressed EGF-induced cell proliferation and transformed colony growth. In conclusion, this study demonstrated the potential of LicoD as a preventive agent for skin carcinogenesis.

• International Journal of Railway
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• v.5 no.2
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• pp.77-83
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• 2012

Railroad signaling systems are to control intervals and routes of trains. There are ATS, ATP, ATO and ATC system. Trains are operated in the section which is met on the signaling system because various signaling systems are used in Korea. Hence, trains are not operated in the section which is used in the other signaling system. To solve this problem, recently combined on-board system has been developed. The combined on-board system designed by doubling the ATS, ATP and ATC system to ensure the safety of system. The inductance of antenna is change and in return the resonance frequency of antenna is varied by the electromagnetic induction. Therefore, the information signal is not received exactly in the combined on-board system and in return accidents between trains occur. In this paper, electric model of the combined on-board system for considering the ATS and ATP antenna is presented. Moreover, the mutual inductance including the distance between the ATS and ATP antenna is calculated. As a result of the frequency response of the antennas, the mutual inductance met on operation range of resonance frequency is defined.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.3
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• pp.343-348
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• 2013

This experiment was conducted to evaluate the development of T cells in intrauterine growth retarded (IUGR) piglets at different gestational stages, and tentatively explore the relationship between T cells development and the Notch signaling pathway. A total of 18 crossbred (Landrace${\times}$Large white) primiparous sows were mated at similar weights and estruses and euthanized at d 60, 90 and 110 of gestation with six replicates for each time point. One IUGR and one normal fetus were picked from each litter. The T-cell subsets, mRNA expression of Delta-like1, Delta-like4, Jagged1, and Notch2 genes in the thymus were investigated. Compared to normal piglets, $CD3^+CD4^-CD8^+$ cells in IUGR fetuses at d 90 was 0.13% lower (p<0.05). At d 110 of gestation $CD8^+$ T cells in IUGR fetuses was 0.19% lower (p<0.05). The percentage of $CD8^+$ T cells was 3.14% lower (p<0.05) of the total T cells in IUGR pigs at d 60. The abundance of Notch2 and Delta-like4 mRNA at d 110 was 20.93% higher and 0.77% (p<0.05) lower, and Delta-like1 mRNA at d 90 was 0.19% (p<0.05) higher compared to normal pigs. These results suggested that normal fetuses had a greater proportion of T-cell subsets at earlier gestation periods, and the Notch signaling pathway was likely partially responsible for these differences to some degree.

• BMB Reports
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• v.55 no.8
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• pp.401-406
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• 2022

Ahnak, a large protein first identified as an inhibitor of TGF-β signaling in human neuroblastoma, was recently shown to promote TGF-β in some cancers. The TGF-β signaling pathway regulates cell growth, various biological functions, and cancer growth and metastasis. In this study, we used Ahnak knockout (KO) mice that underwent a 70% partial hepatectomy (PH) to investigate the function of Ahnak in TGF-β signaling during liver regeneration. At the indicated time points after PH, we analyzed the mRNA and protein expression of the TGF -β/Smad signaling pathway and cell cycle-related factors, evaluated the cell cycle through proliferating cell nuclear antigen (PCNA) immunostaining, analyzed the mitotic index by hematoxylin and eosin staining. We also measured the ratio of liver tissue weight to body weight. Activation of TGF-β signaling was confirmed by analyzing the levels of phospho-Smad 2 and 3 in the liver at the indicated time points after PH and was lower in Ahnak KO mice than in WT mice. The expression levels of cyclin B1, D1, and E1; proteins in the Rb/E2F transcriptional pathway, which regulates the cell cycle; and the numbers of PCNA-positive cells were increased in Ahnak KO mice and showed tendencies opposite that of TGF-β expression. During postoperative regeneration, the liver weight to body weight ratio tended to increase faster in Ahnak KO mice. However, 7 days after PH, both groups of mice showed similar rates of regeneration, following which their active regeneration stopped. Analysis of hepatocytes undergoing mitosis showed that there were more mitotic cells in Ahnak KO mice, consistent with the weight ratio. Our findings suggest that Ahnak enhances TGF-β signaling during postoperative liver regeneration, resulting in cell cycle disruption; this highlights a novel role of Ahnak in liver regeneration. These results provide new insight into liver regeneration and potential treatment targets for liver diseases that require surgical treatment.

• Proceedings of the PSK Conference
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• 2000.10a
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• pp.86-87
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• 2000

• Biomolecules & Therapeutics
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• v.23 no.5
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• pp.421-427
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• 2015

Imperatorin has been known to exert many biological functions including anti-inflammatory activity. In this study, we investigated the inhibitory effects of imperatorin on the production of inflammatory mediators in mouse bone marrow-derived mast cells (BMMC). Imperatorin inhibited degranulation and the generation of eicosanoids (leukotriene $C_4$ ($LTC_4$) and prostaglandin $D_2$ ($PGD_2$) in IgE/antigen (Ag)-stimulated BMMC. To elucidate the molecular mechanism involved in this process, we investigated the effect of imperatorin on intracellular signaling in BMMC. Biochemical analyses of the IgE/Ag-mediated signaling pathway demonstrated that imperatorin dramatically attenuated degranulation and the production of 5-lipoxygenase-dependent $LTC_4$ and cyclooxygenase-2-dependent $PGD_2$ through the inhibition of intracellular calcium influx/phospholipase $C{\gamma}1$, cytosolic phospholipase $A_2$/mitogen-activated protein kinases and/or nuclear factor-${\kappa}B$ pathways in BMMC. These results suggest that the effects of imperatorin on inhibition of degranulation and eicosanoid generation through the suppression of multiple steps of IgE/Ag-mediated signaling pathways would be beneficial for the prevention of allergic inflammation.

• Journal of Ginseng Research
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• v.44 no.3
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• pp.435-441
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• 2020

Background: As a process of aging, skeletal muscle mass and function gradually decrease. It is reported that ginsenoside Rb1 and Rb2 play a role as AMP-activated protein kinase activator, resulting in regulating glucose homeostasis, and Rb1 reduces oxidative stress in aged skeletal muscles through activating the phosphatidylinositol 3-kinase/Akt/Nrf2 pathway. We examined the effects of Rb1 and Rb2 on differentiation of the muscle stem cells and myotube formation. Methods: C2C12 myoblasts treated with Rb1 and/or Rb2 were differentiated and induced to myotube formation, followed by immunoblotting for myogenic marker proteins, such as myosin heavy chain, MyoD, and myogenin, or immunostaining for myosin heavy chain or immunoprecipitation analysis for heterodimerization of MyoD/E-proteins. Results: Rb1 and Rb2 enhanced myoblast differentiation through accelerating MyoD/E-protein heterodimerization and increased myotube hypertrophy, accompanied by activation of Akt/mammalian target of rapamycin signaling. In addition, Rb1 and Rb2 induced the MyoD-mediated transdifferentiation of the rhabdomyosarcoma cells into myoblasts. Furthermore, co-treatment with Rb1 and Rb2 had synergistically enhanced myoblast differentiation through Akt activation. Conclusion: Rb1 and Rb2 upregulate myotube growth and myogenic differentiation through activating Akt/mammalian target of rapamycin signaling and inducing myogenic conversion of fibroblasts. Thus, our first finding indicates that Rb1 and Rb2 have strong potential as a helpful remedy to prevent and treat muscle atrophy, such as age-related muscular dystrophy.

• Animal Bioscience
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• v.35 no.7
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• pp.964-974
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• 2022

Objective: The highly pathogenic avian influenza virus (HPAIV) is a threat to the poultry industry and economy and remains a potential source of pandemic infection in humans. Antiviral genes are considered a potential factor for studies on HPAIV resistance. Therefore, in this study, we investigated gene expression related to the mitogen-activated protein kinase (MAPK) signaling pathway by comparing non-infected, HPAI-infected resistant, and susceptible Ri chicken lines. Methods: Resistant (Mx/A; BF2/B21) and susceptible Ri chickens (Mx/G; BF2/B13) were selected by genotyping the Mx and BF2 genes. Then, the tracheal tissues of non-infected and HPAIV H5N1 infected chickens were collected for RNA sequencing. Results: A gene set overlapping test between the analyzed differentially expressed genes (DEGs) and functionally categorized genes was performed, including biological processes of the gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) pathways. A total of 1,794 DEGs were observed between control and H5N1-infected resistant Ri chickens, 432 DEGs between control and infected susceptible Ri chickens, and 1,202 DEGs between infected susceptible and infected resistant Ri chickens. The expression levels of MAPK signaling pathway-related genes (including MyD88, NF-κB, AP-1, c-fos, Jun, JunD, MAX, c-Myc), cytokines (IL-1β, IL-6, IL-8), type I interferons (IFN-α, IFN-β), and IFN-stimulated genes (Mx1, CCL19, OASL, and PRK) were higher in H5N1-infected than in non-infected resistant Ri chickens. MyD88, Jun, JunD, MAX, cytokines, chemokines, IFNs, and IFN-stimulated expressed genes were higher in resistant-infected than in susceptible-infected Ri chickens. Conclusion: Resistant Ri chickens showed higher antiviral activity compared to susceptible Ri chickens, and H5N1-infected resistant Ri chickens had immune responses and antiviral activity (cytokines, chemokines, interferons, and IFN-stimulated genes), which may have been induced through the MAPK signaling pathway in response to H5N1 infection.

• Biomolecules & Therapeutics
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• v.19 no.1
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• pp.21-26
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• 2011

Ceramide is an important lipid mediator of extracellular signals that control various cellular functions, including apoptosis. In this study, we showed that ceramide induced apoptosis in U373MG human glioblastoma cells associated with G1 cell cycle arrest. Treatment of cells with ceramide increased proapoptotic Bax expression and inhibited the expression of antiapoptotic Bcl-2 and Bcl-xL Ceramide also downregulated cyclin E, cyclin D1, cdk 2, and cdk4 which are involved in regulating cell cycle. In addition, ceramide suppressed phosphorylation of Akt, Bad, p70 S6 kinase, and 4E-BP1, suggesting the involvement of Akt/mTOR signaling pathway. Additionally, okadaic acid, an inhibitor of protein phosphatase 2A, partially blocked the ceramide mediated inhibition of phosphorylation of Akt and 4E-BP1. These results suggest that ceramide induces apoptosis in U373MG glioblastoma cells by regulating multiple signaling pathways that involve cell cycle arrest associated with Akt signaling pathway.