• Journal of Life Science
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• v.21 no.1
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• pp.141-145
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• 2011

Actinomycin D is a natural antibiotic that is used in anti-cancer chemotherapy and is known as a transcription inhibitor. Interestingly, actinomycin D induces phosphorylation of signal transducers and activators of transcription 3 (STAT3) in renal cancer Caki cells. In this study, we examined the molecular mechanism of actinomycin D-induced STAT3 phosphorylation. Treatment with actinomycin D induced phosphorylation of STAT3 (Tyr705) in a dose- and time-dependent manner. However, actinomycin D did not induce phosphorylation of STAT3 (Ser727), STAT1 (Tyr701) and STAT1 (Ser727). Moreover, actinomycin D-induced STAT3 phosphorylation was caused by decreased protein and mRNA levels of SOCS3, but not by JAK2 and SHP-1. In addition, other transcription inhibitor (5,6-dichloro-1-b-D-ribofuranosyl benzimidazole; DRB) also induced phosphorylation of STAT3 (Tyr705). Taken together, the present study demonstrates that transcriptional inhibitors (actinomycin D and DRB) induce phosphorylation of STAT3 (Tyr705) in Caki cells by down-regulation of SOCS3.

• Korean Journal of Food Science and Technology
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• v.45 no.4
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• pp.508-514
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• 2013

2Department of Marine Molecular Biotechnology, College of Life Science, Gangneung-Wonju National University Recently, we reported that diarylheptanoid hirsutenone (HST) effectively inactivated T lymphocytes. However, it has not been evaluated whether HST is involved in calcineurin or calmodulin inactivation. In the present study, cells were treated with T-cell inhibitors with or without HST. Our results revealed that HST successfully inhibited expression of T-helper type I (Th1) and Th2 cytokines. Co-treatment with HST and nuclear factor-activated T cell (NFAT) activation inhibitor III (INCA-6) showed a more sensitive effect than that with other inhibitors, suggesting that HST contributes to inhibition of dephosphorylation of NFAT in the cytosol. HST up-regulated cell cycle arrest genes and inhibited the growth of Staphylococcus aureus. These effects were confirmed in an NFAT electrophoretic-mobility shift assay via successful inhibition of NFAT translocation and in the histological recovery in a 2,4-dinitrochloro benzene-induced in vivo model. Taken together, HST was shown to effectively inhibit T-cell activation via inhibition of cytosolic NFAT dephosphorylation, similar to INCA-6.

• Journal of Life Science
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• v.27 no.10
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• pp.1199-1206
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• 2017

The lymphotoxin ${\beta}$ receptor ($LT{\beta}R$), a member of the tumor necrosis factor receptor family, plays an important role in lymphoid tissue's architecture and organogenesis. We found that $LT{\beta}R$ stimulation induced changes in stress fibers (SFs) in fibroblastic reticular cells (FRCs). MLCK and ROCK play critical roles in the regulation of SF formation in cells. The present study was performed to investigate the antifibrotic effects on SF regulation of $LT{\beta}R$ signaling, with a focus on MLCK inhibition. The effect of $LT{\beta}R$ on the SF change was analyzed using immunoblot and fluorescence assays and agonistic $anti-LT{\beta}R$ antibody-treated FRCs. In addition, we checked the level of Rho-guanosine diphosphate (GDP)/guanosine triphosphate (GTP) exchange activity with FRC lysate. Phospho-ezrin proteins acting as membrane-cytoskeleton linkers completely de-phosphorylated in agonistic $anti-LT{\beta}R$ antibody-treated FRCs. The actin bundles rearranged into SFs, where phospho-myosin light chain (p-MLC) co-localized in FRCs. ML7-treated FRCs completely blocked SFs and showed retraction and shrinkage processes comparable to those observed in agonistic $anti-LT{\beta}R$ antibody-treated cells. Inhibition of ROCK activity induced changes in the actin cytoskeleton organization; however, some SFs remained in the cells, while they were completely disrupted by MLCK inhibition with ML7. We showed that the phosphorylation of MLC was completely abolished with $LT{\beta}R$ stimulation in FRCs. When $LT{\beta}R$ was stimulated with the agonistic $anti-LT{\beta}R$ antibody, the Rho-GDP/GTP exchange activity was reduced, however, the activity was not completely abolished. Collectively, the results illustrated that MLCK was potently responsible for the SF regulation triggered via $LT{\beta}R$ signaling in FRCs.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.2
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• pp.253-261
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• 2004

Ginsenosides and green tea extracts show a variety of biomedical efficacies such as anti-aging, anti-oxidation and anti-tumor-promotion effects. (-)-Epigallocatechin-3-gallate (EGCG) has been reported to inhibit the UVB-induced apoptosis by increasing the Bcl-2-to-Bax ratio. We have previously shown that ginsenoside Fl protects human HaCaT cells from ultraviolet-B (UVB)-induced apoptosis by maintaining constant levels of Bcl-2 and Brn-3a. Here, we investigate the combined effect of ginsenoside Fl and EGCG on the protection of human HaCaT keratinocyte against UVB-induced apoptosis. When treated individually, although 5 ${\mu}$M ginsenoside Fl and 50${\mu}$M EGCG protected cells from UVB-induced apoptosis, 2${\mu}$M ginsenoside Fl or 10${\mu}$M EGCG treatment showed very little protection effect. However, cotreatement of 2${\mu}$M ginsenoside Fl and 10${\mu}$M EGCG successfully protected HaCaT cells from UVB-induced cell death. As expected, combining ginsenoside Fl and EGCG efficiently prevented UVB-induced decrease of Bcl-2 and Brn-3a expression. In addition, cotreatment with ginsenoside F1 and EGCG prevented the dephosphorylation of Rb, whereas individual treatment with ginsenoside Fl or EGCG failed to prevent the dephosphorylation of Rb even at high concentrations.