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標題: | 果蠅促進去頭蓋大單元蛋白(dHedls)之發育遺傳分析 Developmental genetic study of Drosophila homologue of Human enhancer of decapping large subunit, dHedls |
作者: | Yi-Chun Liu 劉怡君 |
指導教授: | 周子賓(Tze-Bin Chou) |
關鍵字: | 裂解體,卵生成,訊息核糖核酸分解,細胞增生, P-bodies,oogenesis,mRNA degradation,cell proliferation, |
出版年 : | 2008 |
學位: | 碩士 |
摘要: | 中文摘要
裂解體(Processing bodies,P-bodies)為細胞質中所聚集一群參與5端至3端方向降解mRNA (訊息核糖核酸)之蛋白質。另外,裂解體也包含一些參與抑制mRNA轉譯之蛋白質,監測mRNA品質管制之蛋白質及參與基因沉默之蛋白質。組成裂解體之蛋白質有其同源物存在於酵母菌,果蠅和人類等不同物種之間。在人類細胞中, Hedls (Human enhancer of decapping large subunit)為一裂解體之架構性蛋白質。Hedls能促使hDcp1 (人類去頭蓋蛋白1)及hDcp2 (人類去頭蓋蛋白質2)之結合,且促進hDcp1a對於hDcp2催化去頭蓋之活性。 本篇論文主要探討dHedls對果蠅卵細胞形成期(oogenesis)發育上扮演之角色。經由果蠅跳躍基因(P-element)篩選到一突變對偶基因,dHedlsH159;dHedlsH159同型對偶基因會造成死亡。dHedls突變會造成約12%的胚胎出現部份腹部體節缺失。且知約有15%之 Osk蛋白質擴散而無法正確地貼附在胚胎卵室的後端。 在果蠅S2細胞之細胞質中,dHedls能與果蠅裂解體蛋白之標誌-果蠅去頭蓋蛋白質1 (dDcp1)和果蠅去頭蓋蛋白質2 (dDcp2)座落於同一處;果蠅卵發育過程中(oogenesis),dHedls能與dDcp1和dDcp2在果蠅卵室內的護理細胞和濾泡細胞座落於同一處,知dHedls為果蠅裂解體之一員。當dHedls突變會減少dDcp1和dDcp2在護理細胞質中表現的數量。反之, dHedls大量表現會增加dDcp1和dDcp2在護理細胞質中表現的數量。dHedls之存在對dDcp1和dDcp2進入至護理細胞質之裂解體扮演相當重要的角色。 另外,dHedls突變呈現多種突變性狀,包含卵巢形態異常,護理細胞入侵卵,及過多護理細胞核存於單一卵室。dHedls基因突變於濾泡細胞會破壞卵表層之細胞骨架:且部份dHedls突變的濾泡細胞會造成細胞不正常之增生。因此知dHedls對維持細胞骨架及正常細胞質分裂扮演重要的角色。 Processing bodies (P-bodies) are specific cytoplasmic foci containing proteins involved in the 5’ to 3’ mRNA decay pathway. Some proteins involved in translational repression, mRNA quality control pathway and RNA-mediated gene silencing together with their mRNA targets are also localized to P-bodies. The components of P-bodies are highly conserved among yeast, human and Drosophila. In human cells, Hedls (Human enhancer of decapping large subunit) is a scaffold protein which interacts with human decapping protein 1 (hDcp1a) and human decapping protein 2 (hDcp2). Hedls promotes dDcp1a to enhance hDcp2 decapping activity. The aim of this thesis is to analyze the developmental function of Drosophila Hedls, dHedls, in oogenesis. A dHedls strong mutant allele, dHedlsH159, was recovered from P-element excision screen. dHedlsH159 is a homozygous lethal line. 12% of dHedlsH159 GLC embryos displayed mild posterior group embryonic defects. Osk protein was mislocalized in a scattered manner at the posterior of 15% dHedlsH159 GLC oocytes. In S2 cells, dHedls was colocalized with P-bodies markers such as dDcp1 and dDcp2. During oogenesis, dHedls was colocalized with dDcp1 and dDcp2 in nurse cells and follicle cells. The above experiments indicated that dHedls is a component of Drosophila P-bodies. Morever, the numbers of dDcp1 and dDcp2-staining bodies were decreased in dHedls mutant background. Overexpression of dHedls increased the numbers of dDcp1 and dDcp2-staining bodies in nurse cell. Therefore, dHedls plays an important role in targeting dDcp1 and dDcp2 to cytoplasmic P-bodies of nurse cells during oogenesis. Egg chambers of dHedlsH159 GLC (germline clone) displayed pleiotropic phenotypes. First, abnormal ovary morphology was visible. Second, the entire of nurse cell nuclei protruded into oocyte. Third, the multinucleated nurse cells were observed. Cortical actin cytoarchitecture of oocyte was disrupted in follicle cells of dHedlsH159 mutant clones. Some mutant follicle cells proliferated abnormally. We proposed that dHedls maintains actin cytoskeleton and is required for normal cell cytokinesis. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/26613 |
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顯示於系所單位: | 分子與細胞生物學研究所 |
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