Högback Susanna, Leppimäki Petra, Rudnäs Britt, Björklund Sonja, Slotte J Peter, Törnquist Kid
Department of Biology, Abo Akademi University, BioCity, Artillerigatan 6, 20520 Turku, Finland.
Biochem J. 2003 Feb 15;370(Pt 1):111-9. doi: 10.1042/BJ20020970.
Sphingolipid (SP) derivatives have diverse effects on the regulation of intracellular free calcium concentrations ([Ca2+]i) in a multitude of non-excitable cells. In the present investigation, the effect of C2-ceramide 1-phosphate (C1P) on [Ca2+]i was investigated in thyroid FRTL-5 cells. C1P evoked a concentration-dependent increase in [Ca2+]i, both in a calcium-containing and a calcium-free buffer. A substantial part of the C1P-evoked increase in [Ca2+]i was due to calcium entry. The effect of C1P was attenuated by overnight pretreatment of the cells with pertussis toxin. Similar results were obtained with C8-ceramide 1-phosphate, although the magnitude of the responses was smaller than with C1P. The phospholipase C inhibitor U73122 attenuated the effect of C1P. C1P invoked a small, but significant, increase in inositol 1,4,5-trisphosphate (IP3). However, the effect of C1P on [Ca2+]i was inhibited by neither Xestospongin C, 2-aminoethoxydiphenylborate nor neomycin. C1P mobilized calcium from an IP3-sensitive calcium store, as C1P did not increase [Ca2+]i in cells pretreated with thapsigargin. The effect of C1P on [Ca2+]i was potently attenuated by dihydrosphingosine and dimethylsphingosine, two inhibitors of sphingosine kinase, but not by the inactive SP-derivative N -acetyl sphingosine. Stimulating the cells with C1P evoked an increase in the production of intracellular sphingosine 1-phosphate. C1P did not modulate DNA synthesis or the forskolin-evoked production of cAMP. The results indicate that C1P may be an important SP participating in cellular signalling.
鞘脂（SP）衍生物对多种非兴奋性细胞内游离钙浓度（[Ca2+]i）的调节具有多种作用。在本研究中，研究了C2-神经酰胺1-磷酸（C1P）对甲状腺FRTL-5细胞[Ca2+]i的影响。在含钙和无钙缓冲液中，C1P均引起[Ca2+]i浓度依赖性升高。C1P引起的[Ca2+]i升高的很大一部分是由于钙内流。百日咳毒素过夜预处理细胞可减弱C1P的作用。C8-神经酰胺1-磷酸也得到了类似结果，尽管反应幅度小于C1P。磷脂酶C抑制剂U73122减弱了C1P的作用。C1P引起肌醇1,4,5-三磷酸（IP3）少量但显著增加。然而，C1P对[Ca2+]i的作用既不受西司他汀C、2-氨基乙氧基二苯硼酸也不受新霉素的抑制。C1P从IP3敏感的钙库中动员钙，因为C1P在用毒胡萝卜素预处理的细胞中不会增加[Ca2+]i。鞘氨醇激酶的两种抑制剂二氢鞘氨醇和二甲基鞘氨醇可有效减弱C1P对[Ca2+]i的作用，但无活性的SP衍生物N-乙酰鞘氨醇则无此作用。用C1P刺激细胞可引起细胞内鞘氨醇1-磷酸生成增加。C1P不调节DNA合成或福斯高林引起的cAMP生成。结果表明C1P可能是参与细胞信号传导的一种重要SP。
