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標題: | Processing bodies 在阿拉伯芥從暗型態轉為光型態發育時對mRNA 轉譯時機之選擇性調控 Processing bodies regulate the time for translation of selected mRNAs in Arabidopsis: from skotomorphogenesis to photomorphogenesis |
作者: | Geng-Jen Jang 張耿禎 |
指導教授: | 吳素幸(Shu-Hsing Wu) |
關鍵字: | Processing bodies,DCP5,光型態發育,暗型態發育,轉譯, Processing bodies,DCP5,photomorphogenesis,skotomorphogenesis,translation, |
出版年 : | 2019 |
學位: | 博士 |
摘要: | 光對植物是重要的環境訊息。先前藉由轉錄體和轉譯體的分析,發現光可以促進阿拉伯芥去白化過程中許多基因的轉錄以及轉譯作用。其中,有超過1500個mRNAs的累積量在光照前後並沒有顯著的差異,但是照光後的轉譯效率卻大幅增加。此結果暗示了光可以選擇性調控特定mRNA的轉譯。Processing bodies (p-bodies)是普遍存在各物種中的cytoplasmic granules,其作用為平衡特定mRNA的儲存、降解以及轉譯,但植物中p-bodies的相關研究目前仍相當有限。我們假設白化苗中特定mRNAs可能暫時儲存於p-bodies,這些mRNAs在照光後可以自p-bodies中釋放出來進行轉譯作用,本論文的研究成果支持此假設:首先,阿拉伯芥突變株 dcp5-1有較少的p-bodies,並且顯現不正常的光型態與暗型態發育外表型,此結果顯示p-bodies參與調控植物光型態以及暗型態發育。藉由共軛焦螢光顯微鏡觀察p-bodies動態,發現白化苗子葉中的p-bodies在照光後會明顯減少。透過dcp5-1突變株轉錄體和轉譯體分析,我們發現數以千計的基因在dcp5-1白化苗中有較高的轉譯效率。其中包含合成葉綠素前驅物的重要酵素基因以及調控apical hook開合的PIN-LIKES3基因。本研究證實,當植物幼苗生長在黑暗環境時,細胞內的p-bodies藉由暫時儲存特定mRNAs以降低它們的轉譯效率。當幼苗突破土壤接受到光訊息時,光會驅使p-bodies的減少並且釋放這些mRNAs進行轉譯作用,使植物可以即時產生必要的蛋白質來因應光型態發育。 Germinated plant seeds buried in soil undergo skotomorphogenic development before emergence to reach the light environment. Young seedlings transitioning from dark to light undergo photomorphogenic development. During photomorphogenesis, light alters the transcriptome and enhances the translation of thousands of mRNAs during the dark-to-light transition in Arabidopsis young seedlings. About 1,500 of these mRNAs have comparable abundance before and after light treatment, which implies widespread translational repression in dark-grown seedlings. Processing bodies (p-bodies), the cytoplasmic granules found in diverse organisms, can balance the storage, degradation and translation of mRNAs. However, the function of p-bodies in translation control remains largely unknown in plants. Here I found that an Arabidopsis mutant defective in p-body formation (Decapping 5; dcp5-1) showed reduced fitness under both dark and light conditions. Comparative transcriptome and translatome analyses of wild-type and dcp5-1 seedlings revealed that p-bodies can attenuate the premature translation of specific mRNAs in the dark, including those encoding enzymes for protochlorophyllide synthesis and PIN-LIKES3 for auxin-dependent apical hook opening. When the seedlings protrude from soil, light perception by photoreceptors triggers a reduced accumulation of p-bodies to release the translationally stalled mRNAs for active translation of mRNAs encoding proteins needed for photomorphogenesis. Results obtained will provide mechanistic insights on p-bodies in translation control for proper skotomorphogenesis and timely photomorphogenesis in seedlings. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/21671 |
DOI: | 10.6342/NTU201900998 |
全文授權: | 未授權 |
顯示於系所單位: | 植物科學研究所 |
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