Phosphorylation of the immunomodulatory drug FTY720 by sphingosine kinases
Phosphorylation of the immunomodulatory drug FTY720 by sphingosine kinases
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DOI：
10.1074/jbc.m307687200
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发表时间：
2003-11-28
影响因子：
4.8
通讯作者：
Baumruker, T
中科院分区：
文献类型：
--
作者：
Billich, A;Bornancin, F;Baumruker, T
免疫调节药物FTY 720在体内被磷酸化，并且所得的FTY 720磷酸盐作为鞘氨醇-1-磷酸受体的配体负责该化合物的独特生物学效应。迄今为止，已经有文献报道FTY 720被鼠鞘氨醇激酶（SPHK）1a磷酸化。我们发现，虽然FTY 720也被人SPHK 1磷酸化，但人2型同种型磷酸化药物的效率高30倍，因为FTY 720对SPHK 2的Km较低。类似地，鼠SPHK 2比SPHK 1a更有效。在人SPHK的剪接变体中，N末端延伸的SPHK 2同种型甚至比SPHK 2本身更活跃。另外SPHK超家族成员，即神经酰胺激酶和“SPHK样”蛋白，不能磷酸化鞘氨醇和FTY 720。因此，只有SPHK 1和2似乎能够磷酸化FTY 720。使用选择性测定条件，测量小鼠组织中SPHK 1和SPHK 2的活性。虽然SPHK 2对鞘氨醇的活性通常低于SPHK 1，但在有利于SPHK 2的条件下，FTY 720磷酸化较高。在人内皮细胞中，SPHK 1对鞘氨醇的活性比SPHK 2高2倍，而FTY 720磷酸化在SPHK 2测定条件下快7倍。最后，与啮齿动物血液相比，FTY 720在人血液中磷酸化较差，这与SPHK 1特别是SPHK 2在人血液中的低活性一致。总之，SPHK 1和2都能够磷酸化FTY 720，但SPHK 2在数量上比SPHK 1更重要。
The immunomodulatory drug FTY720 is phosphorylated in vivo, and the resulting FTY720 phosphate as a ligand for sphingosine-1-phosphate receptors is responsible for the unique biological effects of the compound. So far, phosphorylation of FTY720 by murine sphingosine kinase (SPHK) 1a had been documented. We found that, while FTY720 is also phosphorylated by human SPHK1, the human type 2 isoform phosphorylates the drug 30-fold more efficiently, because of a lower K-m of FTY720 for SPHK2. Similarly, murine SPHK2 was more efficient than SPHK1a. Among splice variants of the human SPHKs, an N-terminally extended SPHK2 isoform was even more active than SPHK2 itself. Further SPHK superfamily members, namely ceramide kinase and a "SPHK-like" protein, failed to phosphorylate sphingosine and FTY720. Thus, only SPHK1 and 2 appear to be capable of phosphorylating FTY720. Using selective assay conditions, SPHK1 and 2 activities in murine tissues were measured. While activity of SPHK2 toward sphingosine was generally lower than of SPHK1, FTY720 phosphorylation was higher under conditions favoring SPHK2. In human endothelial cells, while activity of SPHK1 toward sphingosine was 2-fold higher than of SPHK2, FTY720 phosphorylation was 7-fold faster under SPHK2 assay conditions. Finally, FTY720 was poorly phosphorylated in human blood as compared with rodent blood, in line with the low activity of SPHK1 and in particular of SPHK2 in human blood. To conclude, both SPHK1 and 2 are capable of phosphorylating FTY720, but SPHK2 is quantitatively more important than SPHK1.