細胞分化的過程是受到細胞內特定的基因活化互相合作所調控。根據實驗室之前的結果，我們發現到炭疽桿菌（Bacillus anthracis）分泌的致死毒素（lethal toxin，簡稱LT）會阻擋TPA （12-O-tetrdecanoylphorbol-13 acetate）所誘導的HEL（human erythroleukemia）細胞株往巨核細胞分化。經由分析微陣列（microarray）的數據，我們發現BHLHB2、DACH1、LIMK1、RBP5、RIS1等基因在TPA的處理下表現量增加，且在LT前處理後再處理TPA下表現量下降。所以我們假設這些基因可能在正常的巨核細胞分化及LT抑制的巨核細胞分化中扮演重要的角色。我們使用shRNA去分別抑制這些基因的表現，利用流式細胞儀分析TPA所誘發的分化情形是否有被阻擋的現象，我們發現BHLHB2、DACH1、RBP5等基因表現分別受抑制的時候，TPA所誘導的分化情形受到阻礙。根據實驗結果，我們得到的結論是BHLHB2、DACH1、RBP5等基因在巨核細胞的分化上扮演重要的角色。

The process of cell differentiation is regulated by the coordination of cell type-specific gene activation. Our previous studies indicated that anthrax lethal toxin (LT) could suppress TPA (12-O-tetradecanoylphorbol-13 acetate) induced megakaryocytic differentiation in human erythroleukemia (HEL) cell line. Based on microarray data, BHLHB2, DACH1, LIMK1, RBP5, RIS1 genes were up-regulated after TPA treatments and down-regulated upon LT-pretreatments, so we hypothesized that those genes may play important roles in normal and LT-suppressed megakaryocytic differentiation. Using flow cytometry, we found the differentiation abilities (specific surface marker expression and DNA polyploidy) of HEL cell were blocked when each of those genes was knockdown by shRNA. In this study, we have identified BHLHB2, DACH1, RBP5 genes play potential roles in megakaryocytic differentiation.

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Abstract ------------------------------------------------------------Ⅲ
中文摘要 ------------------------------------------------------------Ⅳ
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Content of Figures and Tables ---------------------------------------Ⅵ
Introduction ---------------------------------------------------------1
Materials and Methods ------------------------------------------------9
Results -------------------------------------------------------------17
Discussion ----------------------------------------------------------28
References ----------------------------------------------------------31
Figures and Tables --------------------------------------------------36
Appendices ----------------------------------------------------------52

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