Sphingosine 1-phosphate (S1P) Induces PECAM-1 Phosphorylation through Activating c-Src

S1P經由活化c-Src引發PECAM-1磷酸化

陳又綺(Yo-Chi Chen) ； 李心予(Hsin-Yu Lee)

《Acta Zoologica Taiwanica》 14卷2期 (2004/10) Pp. 159-160

https://doi.org/10.6576/AZT.2004.14.(2).35

摘要

Sphingosine-1-phosphate(S1P)是一個低分子量的水解磷酸脂(LPL)，原本儲存在血小板內。在發炎反應中，S1P由活化的血小板釋出。S1P在活體外幾乎可在各方面調控血管新生以及成熟的過程，包括細胞的趨化現象、分化、增殖、遷移、存活以及微血管發生等。S1P的生理功能以細胞膜上耦合性G蛋白質家族－S1P1至5爲中介，這些蛋白質接著可活化至少三種不同的異三聚體G蛋白質，包括Gi、Gq及G(12/13)。PECAM-1(CD31)是一種在血小板、白血球表面及內皮細胞接合處表現的穿膜蛋白，本實驗室之前的研究顯示S1P在牛及人類內皮細胞上會增進PECAM-1磷酸化。此外，S1P處理會影響人類臍帶血管內皮細胞(HUVECs)表面的PECAM-1局部化，但總體的PECAM-1表現卻不受此處理的影響。在本研究中，我們證實在牛大動脈內皮細胞(BAECs)上，由S1P所引發的PECAM-1酪胺酸磷酸化可被一種Src系激酶抑制劑PP2的前處理所抑制。這些結果顯示Src系激酶可能參與了S1P作用效應的過程。我們接著在用S1P處理的HUVECs及BAECs上使用了c-Src reporter來偵測c-Src活動；實驗結果顯示在HUVECs上，c-Src的酵素活性於S1P處理後幾秒內增加，但在BAECs上卻沒有同樣的結果。S1P在c-Src磷酸化的作用在使用針對於磷酸化c-Src的抗體並西方墨點法的結果中得到確認。這些結果說明了c-Src可能在內皮細胞內S1P磷酸化PECAM-1的過程中扮演重要的角色。

關鍵字

內皮細胞 ； 磷酸化 ； 水解磷酸脂 ； c-Src ； sphingosine 1-phosphate ； PECAM-1

並列摘要

Sphingosine-1-phosphate (S1P) is a low molecular weight lysophospholipid (LPL), stored primarily in platelets. During inflammation, S1P is released from activating platelets. S1P is capable of regulating almost every aspect of angiogenesis and vessel maturation in vitro, including cell chemotaxis, differentiation, proliferation, migration, survival and capillary morphogenesis. The physiological functions of S1P are mediated by ligating with members of G-protein coupled receptors: S1P1 through 5, which could then activate more than three different heterotrimeric GTP proteins-including Gi、Gq and G(12/13). PECAM-1 (CD31) is a trans-membrane protein expressed on the surface of platelets, leukocytes, and junctions of endothelial cells. Previous studies in our laboratory had shown that S1P enhances phosphorylation of PECAM-1 in both human and bovine endothelial cells. In addition, S1P treatment would affect PECAM-1 localization on cell surface of human umbilical vein endothelial cells (HUVECs). However, the total PECAM-1 expression was not affected by these treatments. In this study, we showed that the tyrosine phosphorylation of PECAM-1 induced by S1P was inhibited by pretreatment with PP2, a Src family kinase inhibitor, in bovine aortic endothelial cells (BAECs). These results indicated that Src family kinases might mediate these effects of S1P. We used c-Src reporter as a biosensor to detect c-Src activity in S1P-treated HUVECs and BAECs. Our results suggest that enzymatic activity of c-src increased within seconds after S1P treatment in HUVECs, but these inductions were not observed in S1Ptreated BAECs. S1P effects on c-Src phosphorylation were also confirmed in Western blots using specific antibodies against phosphorylated c-Src. These results suggest that c-Src may play an important role in mediating the effects of S1P to phosphorylate PECAM-1 in endothelial cells.

並列關鍵字

endothelial cells ； phosphorylationr ； lysophospholipid ； c-Src ； sphingosine 1-phosphate ； PECAM-1