Edsall L C, Van Brocklyn J R, Cuvillier O, Kleuser B, Spiegel S
Department of Biochemistry and Molecular Biology, Georgetown University Medical Center, Washington, D.C. 20007, USA.
Biochemistry. 1998 Sep 15;37(37):12892-8. doi: 10.1021/bi980744d.
Sphingosine 1-phosphate (SPP), a lipid second messenger formed by the action of sphingosine kinase, has been implicated in regulating diverse biological processes, including growth, survival, and differentiation. N,N-Dimethylsphingosine (DMS) inhibits sphingosine kinase and has been used to investigate the biological roles of SPP; however, little is known of the mechanism of inhibition of sphingosine kinase by DMS. In addition, DMS has been shown to inhibit protein kinase C in vitro. Here we report that DMS is a competitive inhibitor of sphingosine kinase from U937 monoblastic leukemia cells, Swiss 3T3 fibroblasts, and PC12 pheochromocytoma cells. DMS decreases basal levels of SPP and prevents increases in SPP in response to physiological stimuli known to activate sphingosine kinase. DMS also effectively increases cellular levels of ceramide in a variety of cell types, and resetting of the ceramide/SPP rheostat may account for the pro-apoptotic effects of DMS. Moreover, DMS, at concentrations which effectively inhibit sphingosine kinase, has no effect on protein kinase C activity or its membrane translocation. Thus, DMS acts as a specific competitive inhibitor of sphingosine kinase in diverse cell types and is a useful tool to elucidate the role of SPP as an intracellular second messenger.
鞘氨醇-1-磷酸（SPP）是一种由鞘氨醇激酶作用形成的脂质第二信使，参与调节多种生物学过程，包括生长、存活和分化。N，N-二甲基鞘氨醇（DMS）可抑制鞘氨醇激酶，并已用于研究SPP的生物学作用；然而，关于DMS抑制鞘氨醇激酶的机制知之甚少。此外，DMS已被证明在体外可抑制蛋白激酶C。在此我们报告，DMS是U937单核细胞白血病细胞、瑞士3T3成纤维细胞和PC12嗜铬细胞瘤细胞中鞘氨醇激酶的竞争性抑制剂。DMS降低SPP的基础水平，并阻止已知激活鞘氨醇激酶的生理刺激导致的SPP增加。DMS还能有效提高多种细胞类型中的神经酰胺细胞水平，神经酰胺/SPP变阻器的重置可能解释了DMS的促凋亡作用。此外，在有效抑制鞘氨醇激酶的浓度下，DMS对蛋白激酶C活性或其膜转位没有影响。因此，DMS在多种细胞类型中作为鞘氨醇激酶的特异性竞争性抑制剂发挥作用，是阐明SPP作为细胞内第二信使作用的有用工具。
