Investigation on physiological roles of sphingosine-1-phosphate signaling system using genetically engineered mice.

我们已经确定鞘氨醇-1-磷酸（S1 P）受体亚型S1P_2作为第一个G蛋白偶联受体，负调节细胞的运动。本研究证实了小鼠黑色素瘤B16-F10细胞内源性表达的S1P_2在体外系统中确实介导了细胞迁移和侵袭的抑制。此外，我们发现用S1 P预处理B16细胞在体内通过内源性表达S1P_2而有效地抑制了尾静脉注射模型中的肺转移。这些结果提出了一个有趣的可能性，S1P_2选择性激动剂可能作为一个抑制肿瘤细胞的侵袭和转移的一个子集的人类恶性肿瘤。与S1P_2形成鲜明对比的是，我们和其他人已经证明S1P_1和S11P_3介导S1 IP刺激细胞迁移，从而作为趋化受体。事实上，在B16黑色素瘤细胞中，后者受体亚型中的任一种的过表达导致对S1 P治疗的响应中的体外迁移和侵袭的刺激和体内肺转移的加重。此外，我们最近发现，S1P_1介导的S1 P刺激血小板源性生长因子在培养的血管平滑肌细胞中上调，通过转录因子KLF 5的作用。结果提示S1P_1在动脉粥样硬化发生发展中的病理生理作用。为了阐明S1 P信号系统在体内的生理作用，我们建立了S1P_2基因敲除小鼠和鞘氨醇激酶转基因小鼠。对这些基因工程小鼠的研究正在进行中。

We have identified sphingosine-1-phosphate(S1P) receptor isoform S1P_2 as the first G protein-coupled receptor that negatively regulates cell mobility. In the present study we demonstrated that endogenously expressed S1P_2 in mouse melanoma B16-F10 cells indeed mediated inhibition of cell migration and invasion in in vitro system. In addition, we found that pretreatment of B16 cells with S1P potently inhibited pulmonary metastasis in vivo in tail vein injection model, via endogenously expressed S1P_2. These results raises an intriguing possibility that S1P_2-selective agonist could serve as an inhibitor of tumor cell invasion and metastasis in a subset of human malignancies. In sharp contrast to S1P_2, we and others have demonstrated that S1P_1 and S1lP_3 mediates S1IP stimulation of cell migration, thereby acting as chemotactic receptors. Indeed, overexpression of either of the latter receptor isoforms in B16 melanoma cells resulted in stimulation of migration and invasion in vitro, and aggravation of lung metastasis in vivo in response to S1P treatment. In addition, we have recently found that S1P_1 mediated S1P stimulation of platelet-derived growth factor upregulation in cultured vascular smooth muscle rails, through die action of a transcription factor KLF5. The results may implicate pathophysiological role for S1P_1 in development of atherosclerosis. In an attempt to elucidate physiological role of S1P signaling system in vivo, we have created S1P_2 knockout mice and sphingosine kinase transgenic mice. Investigation on these genetically engineered mice is now underway.