Scabronine G-methylester enhances secretion of neurotrophic factors mediated by an activation of protein kinase C-ζ
Scabronine G-methylester enhances secretion of neurotrophic factors mediated by an activation of protein kinase C-ζ
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DOI：
10.1124/mol.59.5.1287
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发表时间：
2001-05-01
影响因子：
3.6
通讯作者：
Nakahata, N
中科院分区：
文献类型：
--
作者：
Obara, Y;Kobayashi, H;Nakahata, N
神经胶质细胞释放神经营养因子，维持神经元的功能。在此之前，我们已经证明从粗糙的Sarcodon scabrosus中分离出的scabronine能促进1321N1人星形细胞瘤细胞分泌神经营养因子。在本研究中，我们研究了新合成的苦参碱G-甲酯(ME)诱导1321N1细胞分泌神经营养因子的机制。用卡布罗宁G-ME条件培养液培养1321N1细胞，观察到大鼠嗜铬细胞瘤细胞(PC-12)有明显的神经元分化。SCabronine G-ME可促进1321N1细胞分泌神经生长因子(NGF)和白介素6(IL-6)，增强其基因表达。斯卡布罗宁G-ME可浓度依赖性地抑制卡巴胆碱诱导的1321N1细胞肌醇磷酸蓄积，这种抑制作用可被蛋白激酶C(PKC)亚型抑制剂GF109203X逆转。此外，GF109203X还可抑制卡布罗宁G-ME诱导的NGF和IL-6的mRNA表达及PC-12细胞的分化，表明卡布罗宁G-ME激活了PKC。虽然卡布罗宁G-ME既不能增强传统类型的PKCs的活性，也不能增强新型PKCs的活性，但它在完整的细胞和无细胞的条件下将PKC-Zeta转移到膜上。此外，重组PKC-Zeta活性也被Scabronine G-ME增强，提示PKC-Zeta参与了Scabronine G-ME的作用。在PKC-Zeta下游效应子方面，Scabronine G-ME将核因子-kappaB移位到细胞核，并增强其转录活性。此外，卡布罗宁G-ME可浓度依赖性地引起核因子抑制物kappaB的降解，而GF109203X可抑制其降解。这些结果表明，卡布罗宁G-ME可能通过激活PKC-Zeta而促进1321N1细胞分泌神经营养因子。
Glial cells release neurotrophic factors that maintain neurons functionally. Previously, we have shown that the scabronines isolated from Sarcodon scabrosus enhanced the secretion of neurotrophic factors from 1321N1 human astrocytoma cells. In the present study, we examined the mechanism of newly synthesized scabronine G-methylester (ME)-induced secretion of neurotrophic factors from 1321N1 cells. The dramatic neuronal differentiation of rat pheochromocytoma cells (PC-12) was observed by scabronine G-ME-conditioned medium of 1321N1 cells. Scabronine G-ME increased the secretion of nerve growth factor (NGF) and interleukin-6 (IL-6) from 1321N1 cells with the enhancement of their mRNA expressions. Scabronine G-ME concentration-dependently inhibited the carbachol-induced inositol phosphate accumulation in 1321N1 cells, which was reversed by GF109203X, an inhibitor of protein kinase C (PKC) isoforms. Furthermore, GF109203X inhibited the scabronine G-ME-induced mRNA expressions of both NGF and IL-6 and the differentiation of PC-12 cells, showing that scabronine G-ME activated PKC. Although scabronine G-ME enhanced activities of neither conventional nor novel types of PKCs, it translocated PKC-zeta to membranes in intact cells and cell-free condition. Furthermore, recombinant PKC-zeta activity was also increased by scabronine G-ME, suggesting the involvement of PKC-zeta in the effect of scabronine G-ME. Concerning the downstream effectors of the PKC-zeta, scabronine G-ME translocated nuclear factor-kappaB to nucleus, and enhanced its transcriptional activity. In addition, scabronine G-ME caused the degradation of inhibitor of nuclear factor-kappaB concentration-dependently, which was inhibited by GF109203X. These results suggest that scabronine G-ME potentially enhances the secretion of neurotrophic factors from 1321N1 cells mediated via the activation of PKC-zeta.