臺灣博碩士論文加值系統

在Bone morphogenetic protein (BMP)刺激下使磷酸化的BMP接受體將BMP訊息傳遞下游的Smad蛋白質活化，主要傳遞BMP訊息的接受體調節Smad蛋白質 (R-Smad proteins)分別為Smad1、Smad5和Smad8。受BMP接受體磷酸化的R-Smad和Smad4形成複合體後，進入細胞核，調節BMP目標基因的表現。BMP受接受器一號之接合分子一號 (BRAM1)可和BMP接受器1A結合。然而BRAM1在BMP訊息傳遞的定位尚未清楚。
本篇研究利用免疫沉澱法、西方點墨法和共軛焦顯微鏡來探討BRAM1與BMP接受器和Smad蛋白質間的作用。結果指出，不論是否有BMP2的存在下，BRAM1的確可以與BMP接受器結合，而且兩者的結合主要是經由BRAM1 C端的Mynd domain。在共軛焦顯微鏡來觀察BRAM1和BMP訊息傳遞中的不同蛋白質位置的關係。結果發現，BRAM1和BMP接受器及Smad5會位在同區域，Smad1則否。暗示Smad1和Smad5雖然同屬於BMP訊息傳遞中的R-Smad，但在COS7細胞株的BMP訊息傳遞中，可能扮演了不同的角色。此外，BRAM1影響BMP，顯示BRAM1可干擾BMP訊息傳遞。

Bone morphogenetic protein induces signals through the stimulation of serine/threonine kinase receptors which phosphorylated BMP signaling mediators, Smad1, Smad5 and Smad4. The phosphorylated Smad1/5/4 complex is then translocated to the nucleus and regulates the BMP target genes. BMP receptor associated molecule 1 (BRAM1) is a molecule that associates with BMP receptor IA. However its role in BMP signaling is still unclear. Thus, the specific aims of this study are examined (1) if BRAM1 affects BMP signaling; (2) If so, are the Smad proteins classical BMP signaling mediators involved?
In this study, we demonstrate that BRAM1 interacts with BMP receptor by co-immunoprecipitaion, Western blot and confocal microscopy. The results show that BRAM1 associates with wild type BMP receptor as well as the constitutively activated BMPR. The Mynd domain of BRAM1 is the main region for BRAM1-BMPR interaction. Confocal microscopy study showed that BRAM1 co-localized with BMPR and Smad5, but not with Smad1. Furthermore, BRAM1 prevents the nucleus translocation of Smad4 in response to BMP treatment. Thus the results suggest that BRAM1 may be involved in BMP signaling. This study will provide more information regarding the function of BRAM1.

Contents
English Abstract………………………………….…………….iii
Chinese Abstract……………………………………………….…iv
Introduction…………………………………………………….…1
Material and methods…………………………………………..…8
Results………………………………………………………………13
Discussion ……………………….………………………………18
Reference…………………………….………………...…………21
Figure and Table…………………….……………………………29

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