- 學位論文
水解磷酸脂受器於K562血癌細胞株調控巨核細胞分化之研究
LPA receptor 2 and 3 reversely regulate megakaryopoiesis of K562 human erythroleukemia cells
摘要
紅血球與巨核細胞源自於相同的血球前驅細胞特化而成。在我們過去的研究中發現，水解磷酸脂 (Lysophosphatidic acid, LPA) 經由活化特定的水解磷酸脂受器，參與了紅血球生成的調控。因此，本篇研究進一步利用K562人類血癌細胞株來探討LPA於巨核細胞分化所扮演之角色。實驗結果顯示，在TPA (12-O-Tetradecanoylphorbol-13-acetate) 誘導K562細胞往巨核細胞分化的過程中，水解磷酸脂受器2 (LPA2) 和3 (LPA3) 的表現量會受到調控。我們進一步分析巨核細胞特定表現的膜蛋白CD61，以及核內有絲分裂 (endomitosis) 現象，發現藥劑活化LPA2會抑制TPA誘導之巨核細胞分化。反之，利用基因knockdown的方式降低LPA2的表現可以促進巨核細胞的分化。利用免疫染色，我們進一步發現β-catenin是LPA2下游的調控分子，透過進入細胞核內活化GATA-1以及FLI-1轉錄因子，負向調控巨核細胞之分化。另一方面，我們將細胞以LPA1/3的拮抗劑處理抑制了巨核細胞分化，而藥劑活化LPA3則促進巨核細胞分化。利用基因knockdown方式降低LPA3的表現也使巨核細胞之分化受到抑制。我們更證明LPA3是透過產生reactive oxygen species (ROS)，影響FLI-1轉錄因子的表現，因而正向調控巨核細胞分化。這些結果顯示，LPA2 與LPA3在K562的系統內，可能存在彼此拮抗的關係，並扮演著分子開關的角色反向調控巨核細胞之分化。
並列摘要
Erythrocytes and megakaryocytes (MK) are derived from a common progenitor that undergoes lineage specification. Lysophosphatidic acid (LPA), a lipid growth factor abundant in serum, was shown to be a regulator for erythropoietic process through activating LPA receptor 3 (LPA3). However, whether LPA affects megakaryopoiesis remains unclear. In this study, we used K562 leukemia cell line as a model to investigate the roles of LPA in MK differentiation. We demonstrated that K562 cells express both LPA receptor 2 (LPA2) and LPA3, and the expression levels of LPA2 are higher than LPA3. Treatment with phorbol 12-myristate 13-acetate (TPA), a commonly used megakaryopoiesis inducer, reversely regulates the expressions of LPA2 and LPA3. By pharmacological blockers and knockdown experiments, we revealed that LPA2 suppressed while LPA3 promotes MK differentiation in K562. The LPA2-mediated inhibition is dependent on β-catenin translocation, whereas reactive oxygen species (ROS) generation is a downstream signal for activation of LPA3. Furthermore, hematopoietic transcriptional factors (TFs), including GATA-1 and FLI-1, may involve in these regulatory mechanisms. Taken together, our results suggested that LPA2 and LPA3 may function as a molecular switch and play antagonistic roles during megakaryopoiesis of K562 cells.
並列關鍵字
K562 ； megakaryocyte (MK) ； megakaryopoiesis ； CD61 ； lysophosphatidic acid (LPA) ； LPA receptor參考文獻
延伸閱讀
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