Molecular Pharmacology of Sphingosine 1-Phosphate

描述（由申请人提供）：鞘氨醇1-磷酸（S1P）是一种生物活性脂质，由于S1P储存在红细胞中，在血浆中以三位数纳摩尔水平循环，在全血中以个位数微摩尔水平循环。循环S1P与淋巴细胞运输的滋补性控制、内皮完整性的维持和心率的控制有关。血液中S1P的降解时间以分钟为单位。然而，我们既不知道S1P从循环中清除的机制，也不知道它是如何从细胞转运到血浆的。开发阻断S1P合成或作用的治疗方法的兴趣增加了了解循环S1P水平如何调节以及降低循环S1P张力的急性和慢性后果的紧迫性。在过去的支持期间，我们发现了新的小分子S1P受体激动剂、拮抗剂和合成抑制剂，并开发了S1P信号传导和代谢的转基因小鼠。此外，我们增加了复杂的分析化学能力，能够在小样本中定量鞘脂种类。现在，我们打算利用化学和分子生物学工具，在这一成功的基础上，更深入地了解S1P生物学。具体来说，我们将：（目标1）确定循环S1P水平的范围，测试脂质磷酸酶LPP1负责血浆S1P降解和Spns2运输S1P的假设，（目标2）使用S1P合成抑制剂急性和慢性降低循环S1P，并确定对淋巴细胞运输、毛细血管通透性和心率的影响。我们在S1P化学生物学方面的丰富经验，证明了我们成功地发现了具有药物样特性的S1P受体激动剂和拮抗剂，使我们能够解决有关循环S1P的重要问题。这些答案将提供更多关于S1P生物学的基础知识和实用信息，以指导S1P靶向治疗的进一步发展。

DESCRIPTION (provided by applicant): Sphingosine 1-phosphate (S1P) is a bioactive lipid that circulates at triple digit nanomolar levels in plasma and at single digit micromolar levels in whole blood due to S1P's storage in erythrocytes. Circulating S1P is implicated in tonic control of lymphocyte trafficking, maintenance of endothelial integrity and control of heart rate. Blood S1P is degraded on a time scale of minutes. However, we know neither the mechanism(s) whereby S1P is cleared from circulation nor how it is transported from cells to plasma. The interest in developing therapeutics that block S1P synthesis or action add urgency to developing an understanding of how circulating S1P levels are regulated and the acute and chronic consequences of lowering circulating S1P tone. During the past period of support, we discovered new small molecule S1P receptor agonists, antagonists and synthesis inhibitors and we developed mice genetically altered for S1P signaling and metabolism. Further, we added sophisticated analytical chemistry capabilities that enable quantification of sphingolipid species in small samples. Now we propose to build on this success by using our chemical and molecular biology tools to understand S1P biology more deeply. Specifically, we will: (Aim 1) determine the range of circulating S1P levels, test the hypotheses that the lipid phosphatase LPP1 is responsible for plasma S1P degradation and that Spns2 transports S1P and (Aim 2) use S1P synthesis inhibitors to lower circulating S1P acutely and chronically and determine the effects on lymphocyte trafficking, capillary permeability and heart rate. Our extensive experience in S1P chemical biology, as evidenced by our success in discovering S1P receptor agonist and antagonists with drug-like properties, enables us to address important questions about circulating S1P. The answers will provide both increased fundamental knowledge about S1P biology and practical information to guide the further development of S1P-targeted therapeutics. PUBLIC HEALTH RELEVANCE: Sphingosine 1-phosphate (S1P) is a bioactive lipid that circulates in the bloodstream. The circulating S1P influences the immune system by affecting lymphocyte trafficking, helps to keep small blood vessels from leaking and may tonically depress heart rate. However, we know little about how blood S1P levels are controlled or even the range of S1P concentrations in the blood, but we do know that blood S1P is in a state of rapid flux. Due to the recent approval of a drug that mimics S1P for treating multiple sclerosis, there is a surge of interest in drugs that affect S1P signaling. Among these are investigational drugs that decrease S1P levels by inhibiting its synthesis. Using rodents as surrogates for humans, the research proposed will determine the range of normal S1P levels and explore mechanisms whereby S1P is transported from cells to plasma and how S1P is destroyed in plasma. Further, we will determine the effects of blocking S1P synthesis which rapidly lowers circulating S1P levels on lymphocyte trafficking, vascular leakage and heart rate. By executing this experimental plan, we will learn both about basic S1P biology and predict possible adverse events that accompany therapeutic agents designed to block S1P synthesis.