Interrated research on the physiological role ofbioactive sphingosine-1-phosphate and Edg receptors by using genetically engineered maice.

我们研究了鞘氨醇-L-磷酸(S1P)及其受体在心血管系统和肿瘤进展中的生理和病理生理学作用。SLP通过作用于EDG家族受体发挥多效性作用。与野生型小鼠相比，S1P受体Edg5缺失的小鼠表现出低血压。Edg5基因敲除(Edg5-KO)小鼠对血管紧张素II、促肾上腺皮质激素和一氧化氮合酶抑制剂L-NAME的升压反应程度与野生型小鼠相似。在小鼠股动脉结扎所致的后肢缺血模型中，每日局部肌肉注射可促进缺血肢体血流量的恢复，同时伴有缺血肢体毛细血管密度的增加。我们发明的基于PLGA的缓释S1P也能有效地刺激血流恢复。我们还发现，转S1P合成酶鞘氨醇激酶-1基因的小鼠在缺血后的血流中表现出刺激的恢复。在体外毛细血管样管形成实验中，抗迁移受体Edg5抑制毛细血管形成，阻断Edg5可促进毛细血管形成。因此，Edg5可能是一种抗血管生成受体。Edg1在心肌细胞中表达，但其作用尚不清楚。我们发现，转Edg1基因的小鼠表现出心肌肥大，这种肥大可以被AT1受体拮抗剂阻止。在小鼠尾静脉注射模型中，Edg1激动剂可能通过作用于宿主组织中的Edg1而刺激B16黑色素瘤细胞的肺转移。这些结果表明S1P-EDG系统在心血管内稳态以及心血管和肿瘤病理生理学中发挥着重要作用，并提示了靶向S1P-EDG系统的新的治疗策略的潜在用途。

We investigated physiological and pathophysiological roles of sphingosine-l-phosphate (S1P) and its receptors in the cardiovascular system and tumor progression. Slp exerts its pleiotropic effects through acting on the Edg family receptors. The mice that is null for the S1P receptor Edg5 exhibits hypotension compared with wild type littermates. The Edg5-knockout (Edg5-KO) mice showed similar extents of pressor responses to angiotensin II, ACTH, and the nitric oxide synthase inhibitor L-NAME, as the wild type mice. In the murine hindlimb ischemic model due to femoral artery ligation, daily local intramuscular injection into the ischemic limb promoted the recovery of the blood flow with a concomitant increase in the capillary density in the ischemic limb. The PLGA-based slow-releasing S1P that we invented was also effective in stimulating the blood flow recovery. We also found that the mice transgenic for the S1P-synthesizing enzyme sphingosine kinase-1 showed stimulated recovery in the post-ischemic blood flow. In the in vitro capillary-like tube formation assay, the anti-migratory receptor Edg5 inhibited tube formation, and the blockade of Edg5 stimulated tube formation. Thus, Edg5 is likely anti-angiogenic receptor. Edgl is expressed in cardiomyocytes, however, its role is not known. We found that the mice transgenic for Edgl exhibited cardiac hypertrophy, which was prevented by an AT1 receptor antagonist. In the murine tail vein injection model, an Edgl agonist stimulated lung metastasis of B16 melanoma cells probably through acting on Edgl in the host tissues. These results collectively indicate that S1P-Edg system plays important roles in the cardiovascular homeostasis and the cardiovascular and tumor pathophysiology, and suggest potential usefulness of novel therapeutic strategy to target the S1P-Edg system.