The Expression Profiles of Lysophospholipid Receptors (LPLRs) in Different Endothelial Cells

Sphingosine 1-phosphate（S1P）和Lysophosphatidic acid（LPA）是兩種具有高度生物活性的水解磷酸脂，主要是經由被活化的血小板所釋放到血液之中。水解磷酸脂已知能夠透過與細胞膜上的一類G蛋白結合接受器結合，來引發細胞內一連串的訊息傳遞路徑，進而調控許多與內皮細胞相關的生理反應，例如：傷口癒合、血管新生、細胞附著等。此家族之G蛋白結合接受器，目前發現共有八種：其中S1P1到S1P5為S1P之接受器，而LPA1到LPA3則是LPA之接受器。水解磷酸脂接受器在細胞上的表現，已知會隨著不同細胞類型與細胞發育階段而不同。但對於不同來源之內皮細胞，其表面之水解磷酸脂接受器表現情形是否有所差異，則尚無相關之文獻探討。本研究針對由人類、小鼠、大鼠與牛四種物種之不同血管所分離出的血管內皮細胞，利用反轉錄－聚合?鏈鎖反應（RT-PCR）來偵測不同水解磷酸脂接受器之表現情形。實驗結果顯示，不同物種來源與不同血管之血管內皮細胞上，所表現之水解磷酸脂接受器都有所不同，而此種差異可能直接影響到不同內皮細胞對水解磷酸脂之生理反應。Sphingosine-1-phosphate (S1P) and lysophosphatidic acid (LPA) are two bioactive lysophospholipids (LPLs), stored primarily in platelets and released during platelet activation. Both LPLs are capable of regulating endothelial cell functions. The physiological functions of S1P and LPA are mediated by interacting with eight different G-protein coupled receptors: S1P1 through 5 and LPA1 through 3, which activate three different heterotrimeric GTP proteins－including Gi、Gq and G(12/13). The expression of LPL receptors in endothelial cells would affect the responses of S1P and LPA to these cells. There is no previous report discussing the expression profiles of LPL receptors in different endothelial cells from various species. In this study, we aim to investigate the expression profiles of S1P and LPA receptors in different endothelial cells isolated from human, rat, mouse and bovine origin. We used RT-PCR to determine LPLs receptors expression profiles in different endothelial cells. Our results indicated that endothelial cells from various species express different LPL receptors. Endothelial cells isolated from the same source of different species also had different LPLs receptors expression profiles. Therefore, different endothelial cells should respond to LPLs in different manners