• Archives of Pharmacal Research
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• 제27권1호
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• pp.68-76
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• 2004

Mistletoe lectin has been reported to induce apoptosis in different cancer cell lines in vitro and to show antitumor activity against a variety of tumors in animal models. We previously demonstrated the Korean mistletoe lectin (Viscum album var. coloratum, VCA)-induced apoptosis by down-regulation of Bcl-2 and telomerase activity and by up-regulation of Bax through p53- and p21-independent pathway in hepatoma cells. In the present study, we observed the induction of apoptotic cell death through activation of caspase-3 and the inhibition of telomerase activity through transcriptional down-regulation of hTERT in the VCA-treated A253 cells. We also observed the inhibition of telomerase activity and induction of apoptosis resulted from dephosphorylation of Akt in the survival signaling pathways. In addition, combining VCA with the inhibitors of phosphatidylinositol 3-kinase (PI3-kinase) upstream of Akt, wortmannin and LY294002 showed an additive inhibitory effect of telomerase activity. In contrast, the inhibitor of protein phosphatase 2A (PP2A), okadaic acid inhibited VCA-induced dephosphorylation of Akt and inhibition of telomerase activity. Taken together, VCA induces apoptotic cell death through Akt signaling pathway in correlated with the inhibition of telomerase activity and the activation of caspase-3. From these results, together with our previous studies, we suggest that VCA triggers molecular changes that resulting in the inhibition of cell growth and the induction of apoptotic cell death of cancer cells, which suggest that VCA may be useful as chemotherapeutic agent for cancer cells.

• Journal of Microbiology and Biotechnology
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• 제29권1호
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• pp.30-36
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• 2019

Numerous studies have reported that enteric neurons involved in controlling neurotransmitter secretion and motility in the gut critically contribute to the progression of gut inflammation. Clostridium difficile toxins, which cause severe colonic inflammation, are also known to affect enteric neurons. Our previous study showed that C. difficile toxin A directly induces neural cell toxicities, such as viability loss and apoptosis. In the current study, we attempted to identify a potent inhibitor of toxin A-induced neural cell toxicity that may aid in managing toxin A-induced gut inflammation. In our recent study, we found that the Korea dung beetle-derived antimicrobial peptide CopA3 completely blocked neural cell apoptosis caused by okadaic acid or 6-OHDA. Here, we examined whether the antimicrobial peptide CopA3 inhibited toxin A-induced neural cell damage. In neuroblastoma SH-SY5Y cells, CopA3 treatment protected against both apoptosis and viability loss caused by toxin A. CopA3 also completely inhibited activation of the pro-apoptotic factor, caspase-3. Additionally, CopA3 rescued toxin A-induced downregulation of neural cell proliferation. However, CopA3 had no effect on signaling through ROS/p38 $MAPK/p27^{kip1}$, suggesting that CopA3 inhibits toxin A-induced neural cell toxicity independent of this well-characterized toxin A pathway. Our data further suggest that ability of CopA3 to rescue toxin A-induced neural cell damage may also ameliorate the gut inflammation caused by toxin A.

• The Korean Journal of Physiology and Pharmacology
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• 제4권6호
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• pp.445-453
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• 2000

The present investigation tested the hypothesis that the activation of protein kinase G (PKG) leads to a phosphorylation of $Ca^{2+}-activated$ potassium channel $(K_{Ca}\;channel)$ and is involved in the activation of $K_{Ca}$ channel activity in cerebral arterial smooth muscle cells of the rabbit. Single-channel currents were recorded in cell-attached and inside-out patch configurations of patch-clamp techniques. Both molsidomine derivative 3-morpholinosydnonimine-N-ethylcarbamide $(SIN-1,\;50\;{\mu}M)$ and 8-(4-Chlorophenylthio)-guanosine-3',5'-cyclic monophosphate $(8-pCPT-cGMP,\;100\;{\mu}M),$ a membrane-permeable analogue of cGMP, increased the $K_{Ca}$ channel activity in the cell-attached patch configuration, and the effect was removed upon washout of the drugs. In inside-out patches, single-channel current amplitude was not changed by SIN-1 and 8-pCPT-cGMP. Application of ATP $(100\;{\mu}M),$ cGMP $(100\;{\mu}M),$ ATP+cGMP $(100\;{\mu}M\;each),$ PKG $(5\;U/{\mu}l),$ ATP $(100\;{\mu}M)+PKG\;(5\;U/{\mu}l),$ or cGMP $(100\;{\mu}M)+PKG\;(5\;U/{\mu}l)$ did not increase the channel activity. ATP $(100\;{\mu}M)+cGMP\;(100\;{\mu}M)+PKG\;(5\;U/{\mu}l)$ added directly to the intracellular phase of inside-out patches increased the channel activity with no changes in the conductance. The heat-inactivated PKG had no effect on the channel activity, and the effect of PKG was inhibited by 8-(4-Chlorophenylthio)-guanosine-3',5'-cyclic monophosphate, Rp-isomer $(Rp-pCPT-cGMP,\;100\;{\mu}M),$ a potent inhibitor of PKG or protein phosphatase 2A (PP2A, 1 U/ml). In the presence of okadaic acid (OA, 5 nM), PP2A had no effect on the channel activity. The $K_{Ca}$ channel activity spontaneously decayed to the control level upon washout of ATP, cGMP and PKG, and this was prevented by OA (5 nM) in the medium. These results suggest that the PKG-mediated phosphorylations of $K_{Ca}$ channels, or some associated proteins in the membrane patch increase the activity of the $K_{Ca}$ channel, and the activation may be associated with the vasodilating action.

• 대한소아치과학회지
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• 제29권3호
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• pp.337-344
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• 2002

조골 세포의 분화에 중요한 역할을 하는 전사 인자인 Runx2는 그 역할은 많이 알려져 있지만, 이를 조절하는 신호 전달체계에 대해서는 많이 알려지지 않았다. 이에 본 연구에서는 조골 세포의 분화 및 증식에 영향을 미친다고 알려진 PKC 및 MAPK pathway가 Runx2에 미치는 영향을 알아보고자 하였다. PKC활성화에 따른 Runx2의 전사 활성 및 발현 양상을 관찰하기 위해 6XOSE2-C2C12 cell에 PKC 활성제를 처리하여 luciferase assay와 Northern blot analysis를 시행하였다. MAPK 활성화에 따른 Runx2의 전사 활성을 관찰하기 위해 MAPK 활성제를 6XOSE2-C2C12 cell에 처리하여 luciferase assay를 시행하였다. 두 신호 전달 체계의 활성화에 따른 골 표지 유전자의 전사 양상을 관찰하기 위해 osteocalcin과 osteopontin을 transient transfection한 C2C12 cell에 각 신호 전달 체계의 활성제를 처리하여 luciferase assay를 시행하였다. 또한 각 신호 전달 체계가 상호 작용하는지 알아보기 위하여 MAPK 억제제를 전처리하여 MAPK pathway를 차단한 1 시간 뒤 PKC 활성제를 처리하고 luciferase assay를 시행하여 Runx2의 전사 활성을 관찰하였다. 이상의 실험으로 다음과 같은 결론을 얻었다. - PKC pathway의 활성화는 Runx2의 전사 활성 및 발현을 증가시키고 이로 인해 그의 영향을 받는 골 표지 유전자 (osteopontin, osteocalcin)의 전사도 증가한다. - MAPK pathway의 활성화는 Runx2 및 골 표지 유전자 (osteopontin, osteocalcin)의 전사활성을 증가시킨다. - PKC pathway는 MAPK pathway를 경유하여 Runx2의 전사 활성을 조절한다.

• 한국식품위생안전성학회지
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• 제33권5호
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• pp.404-411
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• 2018

본 연구는 2013년부터 2017년까지 경남 한산 거제만 해역에서 생산되는 패류에 대한 위생지표세균, 마비성 패류독소, 설사성 패류독소를 분석하여 세균학적 독물학적 안전성을 평가하였다. 굴 시료 404점에 대한 분변계대장균은 < 18~330 MPN/100 g의 범위를 나타내었으나, 대장균 230 E. coli MPN/100 g을 초과한 시료는 없었다. 굴 수확시기 동안 분석한 대장균의 기하학적 평균치는 24.3 MPN/100 g으로 매우 낮게 나타났다. 한산 거제만해역에서 생산되는 굴의 세균학적 안전성을 평가한 결과, 식품위생법의 생식용 굴에 대한 위생기준을 만족하였고, EU의 패류생산해역 A등급 기준에 부합하였다. 한산 거제만해역의 독물학적 평가를 위해 굴 532개 시료와 패류독소 지표종인 지중해담치 268개 시료에 대한 분석을 실시하였다. 마비성패류독소는 2013년 4월에 지중해담치 3개 시료에서 1.20~2.29 mg/kg 범위로 기준을 초과하여 검출되었으나, 굴시료에서는 전혀 검출되지 않았다. 총 120개 시료에서 설사성패류독소를 분석하였으나, 정량한계 이하로 매우 낮게 나타났다. 독물학적 안전성 평가결과, 굴 시료에서는 마비성 및 설사성패류독소가 전혀 검출되지 않았으나, 지표종인 지중해담치에서는 마비성패류독소 기준치를 초과한 것으로 나타나 지속적인 모니터링과 안전관리가 요구되었다.