National Taiwan Ocean University Institutional Repository:Item 987654321/17886
English  |  正體中文  |  简体中文  |  全文笔数/总笔数 : 27320/39164
造访人次 : 2475758      在线人数 : 40
RC Version 4.0 © Powered By DSPACE, MIT. Enhanced by NTU Library IR team.
搜寻范围 进阶搜寻

jsp.display-item.identifier=請使用永久網址來引用或連結此文件: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/17886

题名: HIF2α在視網膜發育的功能
Function of HIF2α on retina development
作者: Po-Han Lee
李柏翰
贡献者: NTOU:Institute of Bioscience and Biotechnology
國立臺灣海洋大學:生物科技研究所
关键词: 斑馬魚;低氧誘發因子;視網膜
zebrafish;HIF2α;retina
日期: 2010
上传时间: 2011-07-04
摘要: 在脊椎動物的胚胎發育中,bHLH/PAS 蛋白扮演重要的角色。其中的低氧誘發蛋白(hypoxia-inducible factor,HIFs),負責調控細胞內供氧的平衡,在低氧的狀況下,會進入細胞核,與ARNT形成異偶合體(heterodimer),結合至下游基因的HRE序列(hypoxia responsible element)調控細胞缺氧時的反應。 過去的研究發現,斑馬魚hif1α/-2α/-3α同時弱化會抑制視網膜兩極細胞 (bipolar cell)的vsx1和桿狀感光細胞 (rod-photoreceptor) 的視紫蛋白 (Rhodopsin) 基因rho表現,顯示視網膜的發育受到抑制。隨後分別弱化hif1α、hif2α及hif3α後觀察發現,hif2α弱化後對rho有明顯的影響。序列分析發現rho上游啟動子含有多個HIF所辨識的HRE序列,顯示HIF2α有可能直接調控rho轉錄。為了證明此點,本實驗中將啟動子上游2400bp片段內的HRE進行定點突變後,發現並不影響報導基因在視網膜上的專一性表現,顯示rho啟動子並未接受HIF的直接控制。先前的研究發現,在斑馬魚中,HIF2α會藉由控制細胞凋亡抑制蛋白(inhibitor of apoptosis proteins) survivin 1與-2的方式影響中樞神經分化。本實驗中其次想證明hif2α弱化後是否也是透過相同的方式抑制視網膜神經分化。在弱化birc5a與5b(survivin1與-2)的實驗中,發現皆會抑制rho的表現,顯示survivin 1與-2和眼睛細胞分化間有密切的關係。其次進一步以視網膜發育各時期的標識基因觀察hif2α和birc5a弱化對斑馬魚視網膜發育所造成的影響。結果顯示,HIF2α及survivin 1弱化均會抑制視網膜中晚期的分化,推論HIF2α可能藉由survivin 1影響視網膜分化。顯示在斑馬魚中HIF2α對於視網膜的分化扮演重要的角色。本實驗的結果顯示HIF2α可能是透過控制survivin基因的表現的方式參與視網膜的發育,但並不直接參與rho基因的調控。
Hypoxia-inducible factors (HIFs) are known for their functions in oxygen homeostasis by regulating the genes for glucose uptake and metabolism, erythorpoiesis, angiogenesis, apoptosis and cell proliferation. The HIFs are heterodimeric basic-helix-loop-helix-PAS transcription factors consisting of an oxygen-sensitive alpha subunit and a constitutively expressed beta subunit, also known as ARNT. When cells are subjected to hypoxia, the HIFα factors are stabilized, associate with ARNT and activate the target genes. Previously it was revealed that concurrent knockdown of zebrafish hif1α, -2α and -3α inhibited the bipolar cell marker vsx1 and photoreceptor marker rho transcriptions, indicating that the retinal development was abrogated in hif1α/-2α/-3α morphants. Further investigation revealed that the retinal defects occurred hif1α/-2α/-3α morphant embryos was caused by the action of hif2α antisense morpholino. Knockdown of hif2α eliminated rho expression. There are multiple hypoxia-responsible elements in the upstream promoter regions of rho gene. It raises a possibility that rho transcription is controlled by HIF2 directly. Nevertheless, mutating the HRE sequence in the 2.4 kb of rho promoter fragment did not eliminate the promoter activity, indicating that rho is not controlled directly by HIF2-interaction. It was shown that the differentiation of neural progenitor cells in zebrafish CNS is controlled by HIF2α by means of transcriptional regulation of survivin orthologues Birc5a and Birc5b during embryonic stages. The function of survivin orthologues in retina development is investigated by reverse genetic studies. Knock down of survivin-1/birc5a or survivin-2/birc5b all results in inhibition of rho transcription, suggesting that survivin genes act critical functions in retina development. In hif2α or survivin-1/birc5a morphant embryos, only the transcriptions of mid- and late-stage markers (including huC, neuroD ,vsx1 and rho),but not early stage markers (such as rx1), were affected, indicating hif2α and its downstream target birc5a functions on mid-stages of retina development. In conclusion, this study suggests that HIF2α controls retina development indirectly through its downstream survivin/birc5 genes, but it does not control rho transcription directly.
URI: http://ethesys.lib.ntou.edu.tw/cdrfb3/record/#G0M97360038
http://ntour.ntou.edu.tw/ir/handle/987654321/17886
显示于类别:[生命科學暨生物科技學系] 博碩士論文

文件中的档案:

档案 描述 大小格式浏览次数
index.html0KbHTML284检视/开启


在NTOUR中所有的数据项都受到原著作权保护.

 


著作權政策宣告: 本網站之內容為國立臺灣海洋大學所收錄之機構典藏,無償提供學術研究與公眾教育等公益性使用,請合理使用本網站之內容,以尊重著作權人之權益。
網站維護: 海大圖資處 圖書系統組
DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library IR team Copyright ©   - 回馈