雖然前列環素 (prostacyclin) 受體廣泛存於巨核細胞 (megakaryocyte cells)，但對於前列腺環素接受體 (IP) 在巨核細胞中的訊息傳遞卻少有被研究。HEL細胞是一株具有類似血小板及巨核細胞特性的細胞株，它表現prostaglandin D2 (DP) 、prostaglandin (EP)、 prostaglandin F2 (FP) 、prostacyclin (IP) 及thromboxane A2 (TP) 等五種前列腺素受體。故Human Erythroleukemia (HEL) cells為研究前列腺素受體的訊息傳遞的理想實驗模型。
過去實驗室發現prostacyclin 的致效劑iloprost、carbacyclin或beraprost皆會引起extracellular signal-related kinases1/2 (ERK1/2) 的磷酸化，而往後之實驗則選擇較具IP接受體選擇性的beraprost來進行IP接受體訊息傳遞的研究，並發現於低濃度beraprost (10 nM) 誘導之ERK1/2磷酸化過程，可被PKC 抑制劑GF109203X及 Ro318425抑制，而不被PKA抑制劑H89所影響，由此可知PKC在這訊息調控中扮演著一個重要的角色。在Ca2+的實驗中發現，於低濃度beraprost時並不會使細胞內的鈣增加，故此參與之PKC isoform 可能不具鈣之倚賴性。
本論文研究低濃度beraprost (10 nM) 引起ERK1/2磷酸化的過程中，有那些PKC isoform參與在其中。於利用抗磷酸化PKC 抗體做初步研究，發現其中PKCδ及PKCζ/λ與beraprost所引起的ERK1/2磷酸化較具相關性，且beraprost亦可使PKCδ活化;而beraprost所引起的ERK1/2磷酸化可以被PKCδ專一性的抑制劑rottlerin抑制， ERK1/2活性亦可有效的被rottlerin抑制，故猜測PKCδ在beraprost所引起的ERK1/2磷酸化中扮演著重要的角色。

Although prostacyclin receptor was found in megakaryocytes, less is known about its function and signaling. Human erythroleukemia (HEL) cell a platelet/megakaryocyte like cell line which expresses prostaglandin D2 (DP) , prostaglandin (EP) , prostaglandin F2 (FP) , prostacyclin (IP) and thromboxane A2 (TP) . Therefore, HEL cells are a suitable model for the study of IP receptor signaling pathway.
Previously, we found that the PGI2 analogs iloprost, carbacyclin and beraprost induced ERK1/2 phosphorylation in HEL cells. Later, we used a relatively selective IP agonist beraprost for our study. It was found that at low concentration of beraprost (10 nM) induced ERK1/2 phosphorylation that can not be inhibited by PKA inhibitor H89 while it is inhibited by PKC inhibitors GF109203X and Ro318425. Therefore, PKC may play an important role in low concentration of beraprost (10 nM) induced signaling pathway. Since low concentration of beraprost (10 nM) fails to alleviate intracellular calcium concentration, a Ca++-independent PKC isoform may be involved.
In this thesis, the objective is to study the PKC isoforms involved in low concentration of beraprost induced ERK1/2 phosphorylation. With the use of anti-phosphorylated PKC antibodies, it was found that PKCδ and PKCζ/λ may be related to ERK1/2 phosphorylation, and beraprost can induce PKCδ activity. Moreover, selective PKCδ inhibitor rottlerin inhibited beraprost induced ERK1/2 phosphorylation. Furthermore, beraprost induced ERK1/2 activity is also attentuate by rottlerin. Therefore, PKC involved in low concentration beraprost induced ERK1/2 activity in HEL cells.

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