鑑定α1-acid glycoprotein?動子 DNA 序則結合之蛋白質因數

Abstract

α1 - acid glycoprotein ( AGP)為一在急性發炎反應 ( acute phase)時增加的蛋白質，在其5 端序列中本實驗室定出 A -E 等五個結合區（cis - elememt ) ，並且選殖到一個轉錄子 AGP / EBP 能和 A , C , D , E 四個結合區生成結合，經序列的比較發現 D 結合區的序列和 6 - 16 , ISG54 , β-interferon , angiotensinogen ，等的起動子（ promoter） 之部份序列有很大的相似性，而這些序列分別為 NF - KB , ISGF3 的結合區，而且這些序列對這些基因的調控非常重要． 本論文利用大鼠肝細胞萃取液做為研究的材料， D 結合區做為探針，利用 band shift assay ，並配合 heparin- agarose 管柱層析的技術，發現在細胞質萃取液中具有能和 D 結合區生成結合的活性存在，同時經由cross -competition 的方式證實其並非 NF–KB 或 ISGF3 ，而且在細胞核萃取液中亦有類似的活性存在，並且對此細胞質因數做了熱安定性，分子量和組織特異性等理化特性的鑑定．至於此細胞質因數in vivo中所扮演的角色，還有其是否有轉移到核中都需要進一步的研究。

α1-acid glycoprotein (AGP) is an acute phase protein, whose concentration of mRNA and protein increased 10 to 100 folds within acute phase reaction. These increases are attributed to AGP gene transcriptional rate. Regulation of transcription in higher eukaryotes is partially mediated by cis-acting DNA element recognized by some transcription factors. We have identified five cis-elements, named A-D, in the 5-flanking region of the Agp gene. We also have cloned a transcription factor, AGP/EBP, could be bound four of them. Factors which bind to the sequence over laping with the D motif has been detected by band shift assay. The sequence recognized by these factors is similary to the one recognized by NF-KB or interferon-stimulated gene factor (ISGF). However these factors are distinct from NF-KB or ISGF. Moreover these factors could be detected in the cytop lasm. The molecular weight , heat stability, tissue-distribuction of these factors have been determined, How these factors contributed in AGP regulation will be studied further.