Ceramide stimulates a cytosolic protein phosphatase.
Ceramide stimulates a cytosolic protein phosphatase.
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DOI：
10.1016/s0021-9258(18)42727-5
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发表时间：
1992-03
期刊：
影响因子：
--
通讯作者：
R. Dobrowsky;Yueuf A. Hannung
中科院分区：
文献类型：
--
作者：
R. Dobrowsky;Yueuf A. Hannung
已经确定了一个鞘磷脂循环，在这个循环中，某些细胞外因素的作用导致可逆的鞘磷脂水解和伴随而来的神经酰胺的产生。此外，一种细胞通透性神经酰胺C2-神经酰胺(N-乙酰鞘氨醇)是一种有效的细胞增殖和分化调节剂。我们在此报告C2-神经酰胺、C6-神经酰胺和天然神经酰胺以剂量依赖的方式激活胞浆丝氨酸/苏氨酸蛋白磷酸酶。当神经酰胺浓度低至0.1微米时，观察到初始激活，峰值响应发生在5-10微米。然而，其他密切相关的鞘磷脂，鞘氨醇和鞘磷脂，基本上是不活跃的。蛋白磷酸酶抑制剂冈田酸对神经酰胺刺激的磷酸酶有抑制作用，IC50为0.1-1 nM，与神经酰胺浓度有关。神经酰胺刺激的磷酸酶对镁、锰离子不敏感。使用顺序阴离子交换层析，神经酰胺刺激的磷酸酶活性可以从神经酰胺非反应性磷酸酶中分离出来。神经酰胺对部分纯化的酶活力有3.5倍的刺激作用。将磷酸酶确定为神经酰胺作用的分子靶点，定义了一条新的细胞内信号通路，该通路可能在调节细胞增殖和分化方面发挥作用。
A sphingomyelin cycle has been identified whereby the action of certain extracellular agents results in reversible sphingomyelin hydrolysis and the concomitant generation of ceramide. Moreover, a cell-permeable ceramide, C2-ceramide (N-acetylsphingosine), is a potent modulator of cell proliferation and differentiation. We report herein that C2-ceramide, C6-ceramide, and natural ceramides activate a cytosolic serine/threonine protein phosphatase in a dose-dependent manner. Initial activation is observed at concentrations of ceramide as low as 0.1 microM with peak response occurring at 5-10 microM. However, other closely related sphingolipids, sphingosine and sphingomyelin, were largely inactive. Ceramide-stimulated phosphatase was inhibited by okadaic acid, an inhibitor of protein phosphatases, with an IC50 of 0.1-1 nM, depending on the concentration of ceramide. Ceramide-stimulated phosphatase was insensitive to Mg2+ and Mn2+ cations. Using sequential anion exchange chromatography, ceramide-stimulated phosphatase activity could be resolved from ceramide-nonresponsive phosphatases. The activity of partially purified enzyme was stimulated 3.5-fold by ceramide. The identification of a phosphatase as a molecular target for the action of ceramide defines a novel intracellular signaling pathway with potential roles in the regulation of cell proliferation and differentiation.