| Summary: | 碩士 === 國立臺灣大學 === 動物學研究所 === 96 === Sphingosine 1-phosphate (S1P) is a lysophospholipid growth factor, which has been implicated in regulating various cellular behaviors. The cellular effects of S1P are mediated by binding to a family of G protein-coupled receptors (GPCRs), designated S1P1 through S1P5. By siRNA approaches, we have demonstrated that S1P1 mediated multiple important cellular functions, such as the phosphorylation of Src kinase, the expression of ICAM-1, IL-8 and MCP-1 in human umbilical vein endothelial cells (HUVECs). It has recently been shown that the O-sulfation of the tyrosine residues at N-terminal of S1P1 catalyzed by ATP-sulfurylase plays an important role for S1P1 mediated signaling. However, the molecular mechanisms of S1P1 sulfation-regulated cell functions remain unknown. In the present study, pre-incubation of 10 mM sodium chlorate, an inhibitor of ATP-sulfurylase, significantly inhibited S1P-stimulated Src phosphorylation but not ICAM-1 expression in HUVECs. In cell migration assay, S1P regulated cell migration, actin rearrangement and lamellipodia formation was affected by tyrosine sulfation of S1P1. Furthermore, by two dimensional SDS-PAGE of S1P- and sodium chlorate-treated HUVEC lysates, we have identified 28 proteins were affected by sulfated S1P1 through analysis using Image Master Software. These results imply that sulfation of the tyrosine residues at N-terminal of S1P1 might play important roles on S1P1 mediated signaling in HUVECs.
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