Expression Pattern and Functional Analysis of Zebrafish FTZ-F1 Gene

• Main Authors: Wang, Hsin-wei, 汪心薇
• Other Authors: Chung Bon-chu
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/48652011673581664721

碩士 === 國立臺灣大學 === 動物學系 === 86 === FTZ-F1是首先在果蠅中發現，能夠活化homeodomain 蛋白質 Fushi- tarazu (Ftz)表現的一個轉錄因子，因此被稱為Fushi-tarazu Factor 1。許多生物如斑馬魚體內的同系物(zFF1)已經被發現，由於FTZ-F1是核 受體蛋白質中的一員，而這類的蛋白質通常在生物體內有著重要的功能， 例如老鼠SF1 (steroidogenic factor 1)就是在哺乳動物體內對腎上腺和 性腺發育有重要的影響；而大鼠FTF (fetoprotein transcription factor)則對肝等內臟形成有影響。因此為了解zFF1在斑馬魚胚胎中所扮 演的角色，我們想要研究zFF1的表現型態及調控機制。從RT-PCR的結果， 我們發現zFF1在成魚許多的組織中都有表現，顯示其在斑馬魚體內有重要 的功能。另外。目前已知zFF1有兩個分開利用的起始外顯子，即外顯子1 和外顯子2，且各自接到外顯子3。在胚胎發育過程中，zFF1在早期胚層發 育的時候表現較少，真正大量產生則是在Segmentation即體節發育的時期 之後。在表現位置上，zFF1在胚胎的許多地方都有表現，例如頭部腦下垂 體、背部及頭部神經脊細胞和緊靠卵黃囊的內胚層部位及肝胰臟，其中 zFF1A的表現位置和含量都大於zFF1B。另外，在成魚的腦部靠近下視丘的 部位有zFF1的表現。在細胞株中的實驗證明，zFF1的蛋白質可以辨認mSF1 的binding site，並可活化報導基因的表現。對zFF1 外顯子2啟動子所做 的分析發現，有一可能的調控區域位在-79bp到-126bp之間。從這些研究 結果中我們發現，zFF1兩個外顯子的表現型態並無太大差異，但zFF1A在 胚胎發育過程中較zFF1B多。zFF1的蛋白質具有轉錄活化的功能。而zFF1 在胚胎發育過程中的多重表現也顯示其對斑馬魚胚胎某些重要組織的發育 有重要的功能，但與FTF的作用較相似。 Zebrafish FTZ-F1 (zFF1) is a homolog of Drosophila FTZ-F1 that activates the homeodomain proteinFushi-tarazu and belongs to the nuclear hormone receptor superfamily. This superfamily includesmany important members such as steroidogenic factor 1(SF1), a mammalian homolog of FTZ-F1, whichis a key regulator in the synthesis of steroidogenic enzymes and the development of adrenal andgonads ; and fetoprotein-transcription factor (FTF). To find out the role of zFF1 in thedevelopment of zebrafish, we examined the expression pattern and function of zFF1. zFF1 mRNA iswidely distributed in many tissues, as shown in our RT-PCR results, indicating that zFF1 hasessential function. zFF1 has two leader exons, 1 and 2 , which are differentially utilized andare spliced into exon 3. During the process of development, zFF1 starts to be expressed from thesegmentation stage when somites start to form. The in situ hybridization shows zFF1 can beexpressed in the hypothalamus of adult brain and many different areas of the embryo, includingpituitary, neural crest cell and endoderm in the early segmentation stage and mandibular arch,liver and pancreas in the late stage. Transfection studies in Rat1 cells showed that zFF1 canrecognize the consensus sequence of SF1 binding site and transactivate the expression of thereporter gene. Deletion analysis of the zFF1 promoter 2 in Rat1 cells shows that a potentregulatory element may exist between 79bp and 126bp upstream from the transcription start site.Our studies indicate that the utilization of zFF1 exon 1 and 2 is very similar and zFF1 proteinhas the transactivation ability. Also, the expression of zFF1 in the zebrafish embryos impliesthat it may have important function in the development, and is probably more related to FTF.