Inhibition of phosphatidylcholine and phosphatidylethanolamine biosynthesis in rat-2 fibroblasts by cell-permeable ceramides
Inhibition of phosphatidylcholine and phosphatidylethanolamine biosynthesis in rat-2 fibroblasts by cell-permeable ceramides
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DOI：
10.1046/j.1432-1327.1999.00589.x
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发表时间：
1999-08-01
期刊：
影响因子：
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通讯作者：
Houweling, M
中科院分区：
文献类型：
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作者：
Bladergroen, BA;Bussière, M;Houweling, M
磷脂和鞘磷脂是脂源性第二信使的重要前体，如二酰甘油和神经酰胺，它们参与几种信号转导途径，并以此方式介导各种激动剂的作用。通过检测细胞通透性神经酰胺对大鼠成纤维细胞合成磷脂酰胆碱(PtdCho)和磷脂酰乙醇胺(PtdEtn)的影响，研究甘油磷脂和鞘磷脂代谢之间的相互作用。加入短链CH-神经酰胺后，PtdCho和PtdEtn合成的CDP途径受到剂量和时间依赖性的抑制。用50mU的MC-6-神经酰胺处理细胞4h后，标记胆碱和乙醇胺的PtdCHo和PtdEtn的掺入分别减少83%和56%。在较长时间内(大于或等于16h)暴露于50mU的MC-6-神经酰胺可引起细胞凋亡。结构类似物二氢神经酰胺不影响PtdCHo和PtdEtn的合成。在脉冲追逐实验中，CDP-胆碱和CDP-乙醇胺在CH-神经酰胺的影响下积累了放射性胆碱和乙醇胺，表明PtdCho和PtdEtn的合成在CDP途径的最后一步都受到抑制。的确，经C-6-神经酰胺处理的细胞膜部分的胆碱磷酸转移酶和乙醇胺磷酸转移酶活性分别比对照细胞降低了%和43%。没有观察到二酰甘油质量水平或从放射性标记棕榈酸酯合成二酰甘油的变化。结论：C-6-神经酰胺对甘油磷脂合成的影响主要是通过抑制胆碱磷酸转移酶和乙醇胺磷酸转移酶催化的CDP途径的步骤来实现的。
Phospholipids and sphingolipids are important precursors of lipid-derived second messengers such as diacylglycerol and ceramide, which participate in several signal transduction pathways and in that way mediate the effects of various agonists. The cross-talk between glycerophospholipid and sphingolipid metabolism was investigated by examining the effects of cell-permeable ceramides on phosphatidylcholine (PtdCho) and phosphatidylethanolamine (PtdEtn) synthesis in Rat-2 fibroblasts. Addition of short-chain Ch-ceramide to the cells resulted in a dose- and time-dependent inhibition of the CDP-pathways for PtdCho and PtdEtn synthesis. Treatment of cells for 4 h with 50 mu M C-6-ceramide caused an 83% and a 56% decrease in incorporation of radiolabelled choline and ethanolamine into PtdCho and PtdEtn, respectively. Exposure of the cells for longer time-periods (greater than or equal to 16 h) to 50 mu M C-6-ceramide resulted in apoptosis. The structural analogue dihydro-Ch-ceramide did not affect PtdCho and PtdEtn synthesis. In pulse-chase experiments, radioactive choline and ethanolamine accumulated in CDP-choline and CDP-ethanolamine under the influence of Ch-ceramide, suggesting that synthesis of both PtdCho and PtdEtn were inhibited at the final step in the CDP-pathways. Indeed, cholinephosphotransferase and ethanolaminephosphotransferase activities in membrane fractions from C-6-ceramide-treated cells were reduced by 64% and 43%, respectively, when compared with control cells. No changes in diacylglycerol mass levels or synthesis of diacylglycerol from radiolabelled palmitate were observed. It was concluded that C-6-ceramide affected glycerophospholipid synthesis predominantly by inhibition of the step in the CDP-pathways catalysed by cholinephosphotransferase and ethanolaminephosphotransferase.