• Journal of Korean Neurosurgical Society
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• 제46권4호
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• pp.389-396
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• 2009

Objective : Triptolide (TP) has been reported to suppress the expression of mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1), of which main function is to inactivate the extracellular signal-regulated kinase-1/2 (ERK-1/2), the p38 MAPK and the c-Jun N-terminal kinase-1/2 (JNK-1/2), and to exert antiproliferative and pro-apoptotic activities. However, the mechanisms underlying antiproliferative and pro-apoptotic activities of TP are not fully understood. The purpose of this study was to examine whether the down-regulation of MKP-1 expression by TP would account for antiproliferative activity of TP in immortalized HT22 hippocampal cells. Methods : MKP-1 expression and MAPK phosphorylation were analyzed by Western blot. Cell proliferation was assessed by $^3H$-thymidine incorporation. Small interfering RNA (siRNA) against MKP-1, vanadate (a phosphatase inhibitor), U0126 (a specific inhibitor for ERK-1/2), SB203580 (a specific inhibitor for p38 MAPK), and SP600125 (a specific inhibitor for JNK-1/2) were employed to evaluate a possible mechanism of antiproliferative action of TP. Results : At its non-cytotoxic dose, TP suppressed MKP-1 expression, reduced cell growth, and induced persistent ERK-1/2 activation. Similar growth inhibition and ERK-1/2 activation were observed when MKP-1 expression was blocked by MKP-1 siRNA and its activity was inhibited by vanadate. The antiproliferative effects of TP, MKP-1 siRNA, and vanadate were significantly abolished by U0126, but not by SB203580 or SP600125. Conclusion : Our findings suggest that TP inhibits the growth of immortalized HT22 hippocampal cells via persistent ERK-1/2 activation by suppressing MKP-1 expression. Additionally, this study provides evidence supporting that MKP-1 may play an important role in regulation of neuronal cell growth.

• 한국식품영양과학회지
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• 제13권4호
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• pp.451-458
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• 1984

18% casein식(食)을 대조식이(對照食餌)로 하여 분지쇄(分枝?) 아미노산(Leu. lie. Val.)을 첨가(添加)한 실험식이(實驗食餌)의 간부분절제후(肝部分切除後)의 Rat에 대한 영양학적(營養學約) 효과(效果)를 검토(檢討)하였다. 자유채취(自由攝取)시키면, 실험식이군(寶驗食餌群)은 대조식이군(對照食餌群)에 비하여 6일(日)째까지 식이채취량(食餌攝取量)이 적지만, 8 일(日)째부터는 증가하고 체중증가(體重增加)도 그와 평행하였다. 14 일(日)째에 간(肝)의 부분절제(部分切除)를 행하면, 7 일후의 체중(體重)은 식이채취량(食餌攝取量)은 동일(同一)하면서도 실험식이군(實驗食餌群)에서 유의(有意)하게 증가(增加)하였다. 또한 간부분절제후(肝部分切除後) 5 일(日)째의 간재생중량(肝再生重量) 및 간재생지수(肝再生指數)도 유의(有意)하게 증가(增加)를 나타내었다. 이상으로 보아, 분지쇄(分枝?)아미노산 첨가식이(添加食餌)는 재생간(再生肝) Rat에 대하여 체중증가(體重增加) 및 간재생(肝再生) 보호작용(促進作用)에 있어서 영양학적(營養學論) 효과(效果)가 있다는 것이 인정(認定)된다.

• Reproductive and Developmental Biology
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• 제28권4호
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• pp.211-219
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• 2004

The effects of adenosine 5'-triphosphate (ATP) and ATP analogs, P/sub 2y/ purinoceptor agonists, on growth of normal mouse mammary epithelial cells (NMuMG) were examined. Cells were plated onto 24 well plates in DMEM supplemented with 10 % fetal calf serum. After serum starvation for 24 hours, ATP, P/sub 2y/ purinoceptor agonists (AdoPP[NH]P, ATP-α-S, ATP-γ-S, β, γ-me-ATP and 2me-S-ATP), P/sub 2u/ purinoceptor agonist (UTP) and P/sub 2y/ purinoceptor antagonists (Reactive Blue 2, more selective to P/sub 2y/ receptor than PPADS; PPADS) were added. DNA synthesis was estimated as incorporation of 3H-thymidine into DNA (1 hour pulse with 1 μ Ci/ml, 18～19 hours after treatment). ATP, Adopp[NH]P, ATP-α-S or ATP-γ-S, significantly increased DNA synthesis at 1, 10 and 100 μM concentrations with dose-dependency (P<0.05), and the maximum responses of ATP and ATP analogs were shown at 100 μM concentration (P<0.05). The potency order of DNA synthesis was ATP≥ATP- γ -S>Adopp [NH]P>ATP-α-S. β, γ -me-ATP, 2me-S-ATP and UTP did not increase DNA synthesis. In autoradiographic analysis of percentage of S-phase cells, similar results were observed to those of DNA synthesis. Addition of 1, 10 or 100 μM Reactive Blue 2 or PPADS significantly decreased ATP (100 μM)-induced DNA synthesis, however, PPADS was less effective than Reactive Blue 2. In Elvax 40P implant experiment, ATP directly stimulated mammary endbud growth in situ suggesting the physiological regulator of ATP in mammary growth. ATP 100 μM rapidly increased MAPK activity, reaching a maximum at 5 min and then gradually decreasing to the base level in 30 min. ATP analogs, Adopp[NH]P and ATP-γ-S also increased MAPK activity, however, β, γ-me-ATP and 2me-S-ATP did not. The inhibitor of the upstream MAPK kinase (MEK), PD 98059 (25 μM), effectively reduced ATP (100 μM) or EGF(10 ng/ml, as positive control)-induced MAPK activity and DNA synthesis (P<0.05). These results indicate that ATP-induced DNA synthesis was prevented from the direct inhibition of MAPK kinase pathway. Overall results support the hypothesis that the stimulatory effects of normal mouse mammary epithelial growth by addition of ATP or ATP analogs are mediated through mammary tissue specific P/sub 2y/ purinoceptor subtype, and MAPK activation is necessary for the ATP-induced cell growth.