• Title/Summary/Keyword: Gap Junctional Intercellular Communication (GJIC)

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Protective effect of resveratrol on the oxidative stress-induced inhibition of gap junctional intercellular communication in HaCaT keratinocyte

  • Lee, J.C.;Lee, S.M.;Kim, J.H.;Ahn, S.M.;Lee, B.G.;Chang, I.S.
    • Proceedings of the Korean Society of Applied Pharmacology
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    • 2003.11a
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    • pp.65-65
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    • 2003
  • The aim of this study was to investigate the effect of resveratrol on the oxidative stress-induced inhibition of gap junctional intercellular communication (GJIC) in HaCaT keratinocyte. Anti-oxidative activity of resveratrol was measured by a,a-diphenyl-b-picrylhydrazyl (DPPH) assay and dichlorodihydrofluorescein diacetate oxidation assay. GJIC of HaCaT keratinocyte was assessed using the scrape loading/dye transfer technique. Western blots and reverse transcription-polymerase chain reaction were also analyzed for Connexin 43 protein and mRNA expression, respectively. Resveratrol scavenged directly the stable DPPH radical over a concentration range of 4 mg/$\mell$ (78.2 $\pm$ 2.7% of control) to 500 mg/$\mell$ (29.9 $\pm$ 4.2% of control) and prevent to increase the intracellular fluorescence induced by oxidative stress significantly. Ultraviolet A irradiation (UVA) and 12-O-tetradecanoylphorbol-13-acetate markedly reduced GJIC, which was restored by resveratrol. There were no significant differences in the level of Connexin 43 protein and mRNA expression among any of the experimental groups. Our data suggests that resveratrol has the protective effect on the oxidative stress-induced inhibition of gap junctional intercellular communication in HaCaT keratinocyte and this protection is likely due to the scavenging of reactive oxygen species.

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Determination of Flavonoids from Allium victorialis var. platyphyllum and Their Effect on Gap Junctional Intercellular Communication

  • Hong, Eun-Young;Choi, Soo-Im;Kim, Gun-Hee
    • Food Science and Biotechnology
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    • v.16 no.5
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    • pp.747-752
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    • 2007
  • This study was carried out to identify and quantify the flavonoids from 6 different plant parts of Allium victorialis var. platyphyllum (AVP), including the flower, leaf, root, stem, flower stalk, and flower seed, using liquid chromatography/ mass spectrometry. Two major flavonoids were structurally identified as quercetin (3,5,7,3'4,'-pentahydroxyflavone) and kaempferol (3,5,7,4'-tetrahydroxyflavone) at contents of 11.8-25.8 and $6.0-64.4\;{\mu}g/mL$, respectively. In particular, the flower and root plant parts contained the highest amounts of quercetin and kaempferol compared to the other parts. We also assessed the recovery effects of each plant-part extract of AVP on gap junctional intercellular communication (GJIC) in WB-F344 cells by the scrape-loading and dye transfer (SL/DT) method. According to the results, GJIC was reduced by approximately 70.2% ($62.3{\pm}12.5$ cells) compared to the control ($209{\pm}9.5$ cells, 100%) when 12-O-tetradecanoylphorbol-13-acetate (TPA) was treated alone in the WB-F344 rat liver epithelial cells. However, the stem extract (0.2 mg/mL) restored GJIC to basal levels (92%, $204{\pm}2.3$ cells, p<0.01) and the flower extract (0.2 mg/mL) stimulated GJIC to 82.5% ($172.6{\pm}8.3$ cells, p<0.05), when applied together with the TPA.

Effects of Pahs and Pcbs and Their Toxic Metabolites on Inhibition of Gjic and Cell Proliferation in Rat Liver Epithelial Wb-F344 Cells

  • Miroslav, Machala;Jan, Vondracek;Katerina, Chramostova;Lenka, Sindlerova;Pavel, Krcmar;Martina, Pliskova;Katerina, Pencikova;Brad, Upham
    • Environmental Mutagens and Carcinogens
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    • v.23 no.2
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    • pp.56-62
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    • 2003
  • The liver progenitor cells could form a potential target cell population fore both tumor-initiating and -promoting chemicals. Induction of drug-metabolizing and antioxidant enzymes, including AhR-dependent CYP1A1, NQO-1 and AKR1C9, was detected in the rat liver epithelial WB-F344 "stem-like" cells. Additionally, WB-F344 cells express a functional, wild-type form of p53 protein, a biomarker of genotoxic events, and connexin 43, a basic structural unit of gap junctions forming an important type of intercellular communication. In this cellular model, two complementary assays have been established for detection of the modes of action associated with tumor promotion: inhibition of gap junctional intercellular communication (GJIC) and proliferative activity in confluent cells. We found that the PAHs and PCBs, which are AhR agonists, released WB-F344 cells from contact inhibition, increasing both DNA synthesis and cell numbers. Genotoxic effects of some PAHs that lead to apoptosis and cell cycle delay might interfere with the proliferative activity of PAHs. Contrary to that, the nongenotoxic low-molecular-weight PAHs and non-dioxin-like PCB congeners, abundant in the environment, did not significantly affect cell cycle and cell proliferation; however both groups of compounds inhibited GJIC in WB-F344 cells. The release from contact inhibiton by a mechanism that possibly involves the AhR activation, inhibition of GJIC and genotoxic events induced by environmental contaminants are three important modes of action that could play an important role in carcinogenic effects of toxic compounds. The relative potencies to inhibit GJIC, to induce AhR-mediated activity, and to release cells from contact inhibition were determined for a large series of PAHs and PCBs and their metabolites. In vitro bioassays based on detection of events on cellular level (deregulation of GJIC and/or proliferation) or determination of receptor-mediated activities in both ?$stem-like^{\circ}{\times}$ and hepatocyte-like liver cellular models are valuable tools for detection of modes of action of polyaromatic hydrocarbons. They may serve, together with concentration data, as a first step in their risk assessment.

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Differential Expressions of Gap Junction Proteins during Differentiation of Rat Neuronal Stem Cells

  • Yang, Se-Ran;Cho, Sung-Dae;Ahn, Nam-Shik;Jung, Ji-Won;Park, Joon-Suk;Tiep, Nguyen Ba;Park, Ki-Su;Hong, In-Sun;Jo, Eun-Hye;Seo, Min-Seo;Yoon, Byong-Su;Lee, Yong-Soon;Kang, Kyung-Sun
    • Environmental Mutagens and Carcinogens
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    • v.23 no.1
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    • pp.11-15
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    • 2003
  • Gap junctional intercellular communication (GJIC) plays a key role during development, process of tissue differentiation, and in maintenance of adult tissue homeostasis. Neural stem cells leading to formation of cell clusters termed 'neurospheres', can differentiate into neurons, oligodendrocytes, and astrocytes. We investigated the expression levels and distribution of connexin43 (Cx43) and connexin32 (Cx32), abundant gap junctional protein in neural cells and in neurospheres isolated from rat fetus embryonic day (ED) 17. During differentiation of neurospheres, expression of Cx43 and 32 were increased time-dependently within 72 h, and then decreased at 7 day in western blot analysis. TPA-induced inhibition of GJIC was confirmed by decreased fluorescence by SL/DT assay, and induced hyperphosphorylation of Cx43 while no changes in Cx32 levels in western blot assay. Our results indicate that GJIC may be a crucial role in the differentiation of neuronal stem cell. And this GJIC can be inhibited by TPA through the hyperphosphorylation of Cx43.

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Inhibition of Gap Junctional Intercellular Communication by Food Preservatives Potassium Sorbate (소르빈산 칼륨의 GJIC 억제로 인한 간독성 유발)

  • Hwang, Jae-Woong;Chung, Ji-Hye;Jung, Ji-Won;Jung, Ji-Youn;Kim, Sun-Jung;Park, Jung-Ran;Ahn, Ji-Yun;Ha, Tae-Youl;Kim, Sung-Ran;Lee, Yong-Soon;Kang, Kyung-Sun
    • Journal of Food Hygiene and Safety
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    • v.21 no.4
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    • pp.269-273
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    • 2006
  • Potassium Sorbate (PS) is a potassium salt version of sorbic acid, which has antimicrobial and fungistatic features in foods. Therefore, PS is used as a food preservative against fungi and mold. PS has been found to be non-toxic even when taken in large quantities given its trait to be broken down in the body into water and carbon dioxide. Gap Junctional Intercellular Communication (GJIC) is essential in the maintenance of tissue homeostasis during development and differentiation. This study was made of the effects of PS on GJIC in WB-F344 rat liver epithelial (WB) cells. We found dramatic decrease of cell viability in time- and dose-dependent manners when WB cells were treated with PS. The effect of PS on GJIC is strong inhibition, and it took place in parallel with a hyperphosphorylation of connexin 43 expression. The finding that PS interferes with gap junction functionality should be considered with respect to the mechanism of PS-induced hepatotoxicity.

Effect of retinoic acid on the bystander effect in gene therapy using the Herpes Simplex Virus thymidine kinase (Herpes Simplex Virus thymidine kinase gene을 이용한 유전자 치료에서 retinoic acid가 bystander effect에 미치는 영향)

  • Park, Jae Yong;Kim, Chang Ho;Jung, Tae Hoon;Albelda, Steven M.
    • Tuberculosis and Respiratory Diseases
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    • v.44 no.1
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    • pp.162-174
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    • 1997
  • Background : Metabolic cooperation via gap junctional intercellular communication (GJIC) is an important mechanism of the bystander effect in gene therapy using the Herpes Simplex Virus thymidine kinase/ganciclovir (HSVtk) "prodrug" system. Since retinoids have been reported to increase GJIC by induction of connexin 43 expression, we hyporthesized that treatment of tumor cells with retinoic acid could augment the bystander effect of the HSVtk/GCV system and result in improved tumor cell killing by enhancing GJIC. Methods : We transferred HSVtk gene to SKHep-J cell line that does not express connexin43, and also transferred the gene to human and murine mesothelioma cell lines that express connexin43. We verified that retinoic acid enhanced GJIC utilizing a functional double-dye transfer study and evaluated the effects of retinoic acid on the growth rate of tumor cells. We then tested the effects of retinoic acid on bystander-mediated cell killing. Results : Addition of all-trans retinoic acid (RA) increased GJIC in cell lines expressing connexin 43 and was asspciated with more efficient in vitro bystander killing in cells transduced with HSVtk via adenoviral and retroviral vectors. In contrast, there was no increase in the efficiency of the bystander effect after exposure to RA in a cell line which had no delectable connexin 43. Conclusion : These results provide evidence that retinoids can augment the efficiency of cell killing with the HSVtk/GCV system by enhancing bystander effect and may thus be a promising new approach to improve responses in gene therapy utilizing the HSVtk system to treat tumors.

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Effects of Pueraia mirifica on the Experimental Hepatocarcinogenesis in Rats and Gap Junctional Intercellular Communication (랫드의 실험적 간암 발생과정과 Gap Junction을 통한 세포간 정보전달에서 Pueraia mirfica의 효과)

  • 강경선;김경배;이재해;조성대;조종호;박준석;안남식;양세란;정지원
    • Journal of Food Hygiene and Safety
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    • v.16 no.3
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    • pp.212-220
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    • 2001
  • To investigate the modifying effect of Kwao Kreu, Pueraria mirifica (PM), we performed two kind of studies which are the non-surgical medium-term carcinogenicity study and the modulation of gap junctional intercellular communication study. The first study, a non-surgical medium-term carcinogenicity bioassay was done to investigate the modifying effect of Kwao Keru, Pueyaria mirifca (PH), a rejuvenating folk medicine from Thailand, on the male F344 rat liver. Specific pathogen free, male 6-week-old F3444 rats were divided into ten groups. To induce hepatocarcinogenesis, those in all groups were given a single i.p. injection of DEN (200 mg/kg) and were received two i.p. injection of DGA (300 mg/kg) at the ends of weeks 2 and 5. Rats of group 3-6 were given sodium phenobarbital (PB 0.05% in drink). A diet containing 10 mg/kg PM was given to group 2 during the post-initiation phase and to groups 4 and 5 during promotion and initiation phase, respectively. Group 6 was given the experimental diet alone throughout the experiment (8 weeks). Rats of group 7, 8, 9 and 10 were fed 1000 mg/kg PH in the same manner as group 2, 4, 5 and 6. All animals were sacrificed at 8 weeks after DEN administration. Result of the immunohistochemical staining of the glutathione S-transferase placental form (GST-p) indicated that the numbers and areas of the preneoplastic leisions were not significantly changed in all PM treatment group comparing to control group. Also the numbers and areas of GST-p positive foci among group 7, 8, 9 and 10 were not significantly changed in comparing to control group. To study the effect of PM on the modulation of gap junctional intercellular communication, the present study was performed scrape-loading dye transfer (SL/DT) assay in human keratinocytes. The results showed that PM could not modulate GJIC. These results indicate that Pueraria mirifica may have no carcinogenic effects on experimental hepatocarcinogenesis in rats and gap junctional intercellular communication in human keratinocyte.

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