Kharel Yugesh, Morris Emily A, Congdon Molly D, Thorpe Steven B, Tomsig Jose L, Santos Webster L, Lynch Kevin R
Department of Pharmacology, University of Virginia, Charlottesville, Virginia (Y.K., J.L.T., K.R.L.); Department of Chemistry and Virginia Tech Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia (E.A.M., M.D.C., W.L.S.); and SphynKx Therapeutics LLC, Charlottesville, Virginia (S.B.T.)
Department of Pharmacology, University of Virginia, Charlottesville, Virginia (Y.K., J.L.T., K.R.L.); Department of Chemistry and Virginia Tech Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia (E.A.M., M.D.C., W.L.S.); and SphynKx Therapeutics LLC, Charlottesville, Virginia (S.B.T.).
J Pharmacol Exp Ther. 2015 Oct;355(1):23-31. doi: 10.1124/jpet.115.225862. Epub 2015 Aug 4.
Sphingosine 1-phosphate (S1P) levels are significantly higher in blood and lymph than in tissues. This S1P concentration difference is necessary for proper lymphocyte egress from secondary lymphoid tissue and to maintain endothelial barrier integrity. Studies with mice lacking either sphingosine kinase (SphK) type 1 and 2 indicate that these enzymes are the sole biosynthetic source of S1P, but they play different roles in setting S1P blood levels. We have developed a set of drug-like SphK inhibitors, with differing selectivity for the two isoforms of this enzyme. Although all SphK inhibitors tested decrease S1P when applied to cultured U937 cells, only those inhibitors with a bias for SphK2 drove a substantial increase in blood S1P in mice and this rise was detectable within minutes of administration of the inhibitor. Blood S1P also increased in response to SphK2 inhibitors in rats. Mass-labeled S1P was cleared more slowly after intravenous injection into SphK2 inhibitor-treated mice or mice lacking a functional SphK2 gene; thus, the increased accumulation of S1P in the blood appears to result from the decreased clearance of S1P from the blood. Therefore, SphK2 appears to have a function independent of generating S1P in cells. Our results suggest that differential SphK inhibition with a drug might afford a method to manipulate blood S1P levels in either direction while lowering tissue S1P levels.
1-磷酸鞘氨醇（S1P）在血液和淋巴中的水平显著高于组织中的水平。这种S1P浓度差异对于淋巴细胞从次级淋巴组织的正常流出以及维持内皮屏障完整性是必要的。对缺乏1型和2型鞘氨醇激酶（SphK）的小鼠的研究表明，这些酶是S1P的唯一生物合成来源，但它们在设定S1P血液水平方面发挥着不同的作用。我们已经开发出一组类似药物的SphK抑制剂，对该酶的两种同工型具有不同的选择性。尽管所有测试的SphK抑制剂在应用于培养的U937细胞时都会降低S1P，但只有那些对SphK2有偏向性的抑制剂会使小鼠血液中的S1P大幅增加，并且在给予抑制剂后几分钟内就可以检测到这种升高。大鼠对SphK2抑制剂的反应也会使血液中的S1P增加。在静脉注射到经SphK2抑制剂处理的小鼠或缺乏功能性SphK2基因的小鼠中后，质量标记的S1P清除得更慢；因此，血液中S1P积累的增加似乎是由于S1P从血液中的清除减少所致。因此，SphK2似乎具有独立于在细胞中生成S1P的功能。我们的结果表明，用药物进行差异性SphK抑制可能提供一种方法，在降低组织S1P水平的同时，朝任何一个方向操纵血液中的S1P水平。
