Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA.
Biochem J. 2012 Oct 1;447(1):149-57. doi: 10.1042/BJ20120609.
S1P (sphingosine 1-phosphate) is a pleiotropic lipid mediator involved in numerous cellular and physiological functions. Of note among these are cell survival and migration, as well as lymphocyte trafficking. S1P, which exerts its effects via five GPCRs (G-protein-coupled receptors) (S1P1-S1P5), is formed by the action of two SphKs (sphingosine kinases). Although SphK1 is the more intensively studied isotype, SphK2 is unique in it nuclear localization and has been reported to oppose some of the actions ascribed to SphK1. Although several scaffolds of SphK1 inhibitors have been described, there is a scarcity of selective SphK2 inhibitors that are necessary to evaluate the downstream effects of inhibition of this isotype. In the present paper we report a cationic amphiphilic small molecule that is a selective SphK2 inhibitor. In the course of characterizing this compound in wild-type and SphK-null mice, we discovered that administration of the inhibitor to wild-type mice resulted in a rapid increase in blood S1P, which is in contrast with our SphK1 inhibitor that drives circulating S1P levels down. Using a cohort of F2 hybrid mice, we confirmed, compared with wild-type mice, that circulating S1P levels were higher in SphK2-null mice and lower in SphK1-null mice. Thus both SphK1 and SphK2 inhibitors recapitulate the blood S1P levels observed in the corresponding null mice. Moreover, circulating S1P levels mirror SphK2 inhibitor levels, providing a convenient biomarker of target engagement.
S1P（鞘氨醇 1-磷酸）是一种多功能脂质介质，参与多种细胞和生理功能。其中值得注意的是细胞存活和迁移以及淋巴细胞迁移。S1P 通过五种 GPCR（G 蛋白偶联受体）（S1P1-S1P5）发挥作用，由两种 SphK（鞘氨醇激酶）作用形成。尽管 SphK1 是研究更为深入的同工型，但 SphK2 具有独特的核定位，并据报道反对归因于 SphK1 的一些作用。尽管已经描述了几种 SphK1 抑制剂的支架，但缺乏选择性 SphK2 抑制剂，这对于评估这种同工型的抑制的下游影响是必要的。在本文中，我们报告了一种阳离子两亲小分子，它是一种选择性 SphK2 抑制剂。在对野生型和 SphK 缺失小鼠进行该化合物的特征描述过程中，我们发现将抑制剂施用于野生型小鼠会导致血液 S1P 迅速增加，这与我们的 SphK1 抑制剂使循环 S1P 水平降低形成对比。使用一组 F2 杂种小鼠，我们证实与野生型小鼠相比，SphK2 缺失小鼠的循环 S1P 水平较高，SphK1 缺失小鼠的循环 S1P 水平较低。因此，SphK1 和 SphK2 抑制剂都重现了相应的缺失小鼠中观察到的血液 S1P 水平。此外，循环 S1P 水平反映了 SphK2 抑制剂水平，提供了一个方便的靶标结合的生物标志物。
