Involvement of Ca2+, CaMK II and PKA in EGb 761-induced insulin secretion in INS-1 cells
Involvement of Ca2+, CaMK II and PKA in EGb 761-induced insulin secretion in INS-1 cells
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DOI：
10.1016/j.jep.2006.09.001
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发表时间：
2007-03-01
影响因子：
5.4
通讯作者：
Kang, Yup
中科院分区：
文献类型：
--
作者：
Choi, Sung-E.;Shin, Ha-Chul;Kang, Yup
银杏叶提取物的标准型银杏叶提取物EGb761最近被报道具有增强胰岛β细胞功能的作用。为了确定EGb 761是否直接诱导胰岛素分泌，我们用EGb 761处理INS-1大鼠胰岛细胞，然后测量胰岛素的释放。银杏叶提取物761(50微克/毫升)对INS-1细胞的胰岛素分泌有明显刺激作用(P<0.05)，且呈剂量依赖性。为了阐明EGb 761诱导胰岛素分泌的机制，我们研究了钙离子的参与。L类钙通道阻滞剂硝苯地平可阻止EGb 761诱导的胰岛素分泌，且EGb 761本身可升高[Ca~(2+)](I)，提示钙参与了这一过程。为了确定参与EGb 761诱导的胰岛素分泌的蛋白激酶，用不同的激酶抑制剂处理INS-1细胞，并观察它们对EGb 761诱导的胰岛素分泌的影响。钙/钙调蛋白激酶(CaMK)II和蛋白激酶A(PKA)抑制剂KN62和H89可显著抑制EGb 761诱导的胰岛素分泌。免疫印迹研究表明，在EGb 761处理后，CaMK II和PKA底物的磷酸化形式增加。我们的数据表明，EGb 761诱导的胰岛素分泌是由[Ca~(2+)](I)升高和随后激活的CaMK-H和PKA介导的。(C)2006年，爱思唯尔爱尔兰有限公司出版。
EGb 761, a standardized form of Ginkgo biloba L. (Ginkgoaceae) leaf extract, was recently reported to increase pancreatic beta-cell function. To determine whether EGb 761 elicits insulin secretion directly, we treated INS-1 rat beta cells with EGb 761 and then measured insulin release. Treatment of EGb 761 (50 mu g/ml) significantly stimulated insulin secretion in INS-1 cells, compared with untreated control (P < 0.05) and the stimulatory effect of EGb 761 on insulin secretion was dose-dependent. To elucidate the mechanism of EGb 761-induced insulin secretion, we investigated the involvement of calcium. The treatment with nifedipine, an L-type calcium channel blocker, prevented EGb 761-induced insulin secretion and furthermore, EGb 761 itself elevated [Ca2+](i), suggesting the involvement of calcium in this process. To identity the protein kinases involved in EGb 761-induced insulin secretion, INS-1 cells were treated with different kinase inhibitors and their effects on EGb 761-induced secretion were investigated. KN62 and H89, calium/calmodulin kinase (CaMK) II and protein kinase A (PKA) inhibitor, respectively, significantly reduced EGb 761-induced insulin secretion. Immumoblotting studies showed an increase in the phosphorylated-forms of CaMK II and of PKA substrates after EGb 761 treatment. Our data suggest that EGb 761-induced insulin secretion is mediated by [Ca2+](i) elevation and subsequent activation of CaMK H and PKA. (c) 2006 Published by Elsevier Ireland Ltd.