Molecular biological analysis of the lipid morphogen sphingosine-1-phosphate

本研究采用基因打靶、转基因技术和细胞生物学分析等方法，研究了1-磷酸鞘氨醇（S1P）/Edg受体轴的生理和病理作用，建立了Edg5基因敲除小鼠模型。我们发现Edg5受体基因无效突变的小鼠出生时是纯合的，符合孟德尔定律。未观察到Edg5-/-小鼠外观和行为的大体异常。出生后，大约40%的Edg5-/-小鼠在1个月内死亡。早期死亡率增加的原因目前尚不清楚。成年Edg5-/-小鼠血压略低。鞘氨醇激酶是S1P产生的限速酶。与Edg1和Edg3不同，Edg5具有抑制细胞迁移和细胞Rac活性的独特活性，Edg1和Edg3均能抑制Rac活性。我们首次发现Edg5通过G12/13和小的GTdR Rho与Rac的抑制偶联。我们观察到Edg5抑制细胞运动和肿瘤细胞的侵袭，从而抑制体内转移。

We tried to determine physiological and pathological roles of the sphingosine-1-phosphate (S1P)/Edg receptor axis, by using gene targeting and transgenic techniques and cell biological analysis.We generated Edg5 knockout mice, by the standard method. We found that mice homozygous for null mutation of Edg5 receptor gene are born, accordingly to the Mendelian law. Gross abnormality in the appearance and behavior of Edg5-/- mice is not observed. After birth, approximately 40 % of Edg5-/- mice die within 1 month. The reason of this increased mortality in the early stage is not known at present. Adult Edg5-/- mice display slightly lower blood pressure. Sphingosine kinase is a rate-limiting enzyme for the production of S1P. In sphingosine kinase-transgenic mice, the wound-healing process is promoted compared to wild type mice.Edg5 has unique activities to suppress cell migration and cellular Rac, different from Edg1 or Edg3, which both inhibit Rac activity cell migration. We found for the first time that Edg5 couples to inhibition of Rac via G12/13 and the small GTPase Rho. We observed that Edg5 exerts inhibition of cell motility and invasion of tumor cells, resulting in suppression of metastasis in vivo.