果蠅的去頭蓋酵素dDcp1 為一個可能的TGF-β訊息傳遞之轉錄共同調控蛋白

Drosophila decapping protein 1,dDcp1, is a putative TGF-β signaling transcriptional co-activator

徐唯珊(Wei-Shan Hsu)

指導教授 ： 周子賓

國立臺灣大學/生命科學院/分子與細胞生物學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.10281

摘要

果蠅的CG11183最先被認為是人類SMIF基因的同源基因，而被命名為dSMIF。SMIF不但參與變形生長因子貝他(TGF-β)的訊息傳遞，也被證實是一個去頭蓋酵素，因此SMIF基因也被命名為hDcp1a。由於缺乏直接的遺傳證據證明CG11183為果蠅TGF-β訊息傳遞的成員，但是CG11183經證實後具有去頭蓋酵素活性，因此被命名為果蠅的去頭蓋酵素，dDcp1。
為了闡明dDcp1與TGF-β訊息傳遞之間的關聯性，我們以三個方向進行探討:一，以酵母菌融合實驗檢驗dDcp1與TGF-β訊息傳遞成員間的作用力關係。二，以P跳躍元素進行不準確的跳出跳動，取得無功能的dDcp1對偶基因。三，分析dDcp1無功能對偶基因所產生的性狀，期藉此得到直接的證據證實dDcp1為TGF-β訊息傳遞之成員。
經酵母菌融合實驗證實，dDcp1不但與果蠅的Co-Smad，Medea，具有相互作用的能力，且與果蠅的兩個R-Smad，Mad以及dSmad2，亦能相互作用；此外，dDcp1與Co-Smad以及R-Smad可以形成三複體。dDcp1也具有活化轉錄的能力，本身也能與自己形成複體。這些結果指出dDcp1很可能是一個TGF-β訊息傳遞中的轉錄共同調控蛋白。
經兩次P跳躍元素不準確的跳出篩選，dDcp1442pop被證實是一個沒有蛋白質表現的無功能對偶基因。dDcp1442pop使成蟲盤組織細胞以及幼蟲腦的視葉無法發育，並且幼蟲腦的EcR-B1蛋白質表現受到影響。這些現象顯示dDcp1很有可能是一個具有組織特異性之TGF-β訊息傳遞的轉錄共同調控蛋白。

關鍵字

果蠅, TGF-β

並列摘要

CG11183 is the Drosophila homology of SMIF and was named as dSMIF first. SMIF is identified as a transcriptional co-activator in transforming growth factor-β (TGF-β) signaling pathway and it also has decapping activity. Therefore, SMIF is also named as hDcp1a. However, there is no genetic evidence to link CG11183 with Drosophila TGF-β signaling. Moreover, CG11183 was later found to have the intrinsic decapping activity. Therefore, we named CG11183 as Drosophila decapping protein 1(dDcp1).
In order to clarify the relationship between dDcp1 and TGF-β signaling pathway, we approached this aim in three aspects. First, to investigate the possible interaction between dDcp1 and the members in Drosophila TGF-β signaling pathway by yeast two/three-hybrid assay. Second, to create a dDcp1 null allele by imprecise excision screen. Third, to analyze the dDcp1 null phenotype and try to get the direct evidences to connect dDcp1 with TGF-β signaling.
From the one/two/three-hybrid assay, we proved that dDcp1 can interact not only with the Drosophila Co-Smad, Medea, but also with the two Drosophila R-Smads, Mad and dSmad2. It was also certified that dDcp1, R-Smad and Co-Smad form a trimer. Further, dDcp1 is considered to have the ability to form oligomer and has the transactivation activity at the C-terminal. These results imply that dDcp1 is a putative transcriptional co-activator in TGF-β signaling.
After two imprecise excision screens, dDcp1442pop was verified as a null allele. The imaginal discs and potic lobes can not development in dDcp1442pop larvae. Moreover, dDcp1442pop larvae displayed lower EcR-B1 expression in the central brain. These indicate that dDcp1 is a putative tissue-specific transcriptional co-activator in TGF-β signaling.

並列關鍵字

Drosophila, TGF-β

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