Goodemote K A, Mattie M E, Berger A, Spiegel S
Department of Biochemistry and Molecular Biology, Georgetown University Medical Center, Washington, D.C. 20007, USA.
J Biol Chem. 1995 Apr 28;270(17):10272-7. doi: 10.1074/jbc.270.17.10272.
Sphingosine 1-phosphate, a sphingolipid metabolite, was previously reported to increase DNA synthesis in quiescent Swiss 3T3 fibroblasts and to induce transient increases in intracellular free calcium (Zhang, H., Desai, N. N., Olivera, A., Seki, T., Brooker, G., and Spiegel, S. (1991) J. Cell Biol. 114, 155-167). In the present study, pretreatment of Swiss 3T3 fibroblasts with pertussis toxin reduced sphingosine 1-phosphate-induced DNA synthesis. Sphingosine 1-phosphate decreased cellular cAMP levels and also caused a drastic decrease in isoproterenol- and forskolin-stimulated cAMP accumulation. Pertussis toxin treatment prevented the inhibitory effect of sphingosine 1-phosphate on cAMP accumulation, suggesting that a pertussis toxin-sensitive Gi or Gi-like protein may be involved in sphingosine 1-phosphate-mediated inhibition of cAMP accumulation. Mitogenic concentrations of sphingosine 1-phosphate stimulated production of inositol phosphates which was inhibited by pertussis toxin, while the response to bradykinin was not affected. Furthermore, calcium release induced by sphingosine 1-phosphate, but not by bradykinin, was also attenuated by pertussis toxin treatment. However, sphingosine 1-phosphate-induced phosphatidic acid accumulation was unaffected by pertussis toxin. The increase in specific DNA binding activity of activator protein-1, which was induced by treatment of quiescent Swiss 3T3 fibroblasts with sphingosine 1-phosphate, was also inhibited by pertussis toxin. These results suggest that some of the sphingosine 1-phosphate-induced signaling pathways are mediated by G proteins that are substrates for pertussis toxin.
鞘氨醇-1-磷酸，一种鞘脂代谢产物，先前有报道称其可增加静止的瑞士3T3成纤维细胞中的DNA合成，并诱导细胞内游离钙的短暂增加（Zhang, H., Desai, N. N., Olivera, A., Seki, T., Brooker, G., and Spiegel, S. (1991) J. Cell Biol. 114, 155 - 167）。在本研究中，用百日咳毒素预处理瑞士3T3成纤维细胞可降低鞘氨醇-1-磷酸诱导的DNA合成。鞘氨醇-1-磷酸降低细胞内cAMP水平，并且还导致异丙肾上腺素和福斯高林刺激的cAMP积累急剧减少。百日咳毒素处理可防止鞘氨醇-1-磷酸对cAMP积累的抑制作用，表明一种对百日咳毒素敏感的Gi或类Gi蛋白可能参与鞘氨醇-1-磷酸介导的cAMP积累抑制。有丝分裂浓度的鞘氨醇-1-磷酸刺激肌醇磷酸的产生，该产生被百日咳毒素抑制，而对缓激肽的反应不受影响。此外，百日咳毒素处理也减弱了鞘氨醇-1-磷酸诱导的钙释放，但缓激肽诱导的钙释放不受影响。然而，鞘氨醇-1-磷酸诱导的磷脂酸积累不受百日咳毒素影响。静止的瑞士3T3成纤维细胞用鞘氨醇-1-磷酸处理后诱导的激活蛋白-1特异性DNA结合活性的增加也被百日咳毒素抑制。这些结果表明，鞘氨醇-1-磷酸诱导的一些信号通路是由作为百日咳毒素底物的G蛋白介导的。
