Sphingosine kinase expression regulates apoptosis and caspase activation in PC12 cells
Sphingosine kinase expression regulates apoptosis and caspase activation in PC12 cells
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DOI：
10.1046/j.1471-4159.2001.00164.x
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发表时间：
2001-03-01
影响因子：
4.7
通讯作者：
Milstien, S
中科院分区：
文献类型：
--
作者：
Edsall, LC;Cuvillier, O;Milstien, S
1-磷酸鞘氨醇 (SPP) 是一种生物活性鞘脂代谢物，可抑制多种细胞的凋亡，包括大鼠嗜铬细胞瘤 PC12 细胞。阐明 SPP 作用的分子机制因许多因素而变得复杂，包括摄取和代谢，以及特定 G 蛋白偶联 SPP 受体（称为内皮分化基因 1 (EDG-1) 家族）的激活。在本研究中，我们过表达 1 型鞘氨醇激酶 (SPHK1)（一种将鞘氨醇转化为 SPP 的酶），以便更直接地检查细胞内生成的 SPP 的作用。在神经元的存活中。 PC12 细胞中 SPHK1 的强制表达导致激酶活性显着增加，细胞内 SPP 水平相应增加，鞘氨醇和神经酰胺随之减少，并显着抑制营养因子撤除或 C-2-神经酰胺诱导的细胞凋亡。 NGF 可以保护 PC12 细胞免受血清撤药诱导的细胞凋亡，也可以刺激 SPHK1 活性。令人惊讶的是，SPHK1 的过度表达对两种已知的 NGF 刺激的生存途径（细胞外信号调节激酶 ERK 1/2 和 AM）的激活没有影响。然而，营养撤退诱导的应激激活蛋白激酶、c-Jun 氨基末端激酶 (SAPK/JNK) 的激活以及执行性半胱天冬酶 2、3 和 7 的激活均受到显着抑制。此外，这种由 SPHK 抑制剂 N,N-二甲基鞘氨醇阻止的 caspase 激活的消除不受百日咳毒素处理的影响，表明细胞保护作用可能不是由 SPP 与细胞表面 G(1) 偶联 SPP 受体的结合介导的。一致地，即使在通过 NGF 或鞘氨醇处理显着增加细胞 SPP 水平后，也没有检测到 SPP 释放到培养基中。与 PC12 细胞相反，C6 星形胶质瘤细胞分泌 SPP，这表明 SPP 可能是神经胶质细胞产生和分泌的多种已知神经营养因子之一。总的来说，我们的结果表明 SPHK/SPP 可能通过调节 SAPK 和 caspase 的激活在神经元存活中发挥重要作用。
Sphingosine-1-phosphate (SPP), a bioactive sphingolipid metabolite, suppresses apoptosis of many types of cells, including rat pheochromocytoma PC12 cells. Elucidating the molecular mechanism of action of SPP is complicated by many factors, including uptake and metabolism, as well as activation of specific G-protein-coupled SPP receptors, known as the endothelial differentiation gene-1 (EDG-1) family. In this study, we overexpressed type 1 sphingosine kinase (SPHK1), the enzyme that converts sphingosine to SPP, in order to examine more directly the role of intracellularly generated SPP. in neuronal survival. Enforced expression of SPHK1 in PC12 cells resulted in significant increases in kinase activity, with corresponding increases in intracellular SPP levels and concomitant decreases in both sphingosine and ceramide, and marked suppression of apoptosis induced by trophic factor withdrawal or by C-2-ceramide. NGF, which protects PC12 cells from serum withdrawal-induced apoptosis, also stimulated SPHK1 activity. Surprisingly, overexpression of SPHK1 had no effect on activation of two known NGF-stimulated survival pathways, extracellular signal regulated kinase ERK 1/2 and AM. However, trophic withdrawal-induced activation of the stress activated protein kinase, c-Jun amino terminal kinase (SAPK/JNK), and activation of the executionary caspases 2, 3 and 7, were markedly suppressed. Moreover, this abrogation of caspase activation, which was prevented by the SPHK inhibitor N,N-dimethylsphingosine, was not affected by pertussis toxin treatment, indicating that the cytoprotective effect was likely not mediated by binding of SPP to cell surface G(1)-coupled SPP receptors. In agreement, there was no detectable release of SPP into the culture medium, even after substantially increasing cellular SPP levels by NGF or sphingosine treatment. In contrast to PC12 cells, C6 astroglioma cells secreted SPP, suggesting that SPP might be one of a multitude of known neurotrophic factors produced and secreted by glial cells. Collectively, our results indicate that SPHK/SPP may play an important role in neuronal survival by regulating activation of SAPKs and caspases.