Ku蛋白是在1981年發現於自體免疫缺失病人血清中的一種自體抗原，它是由兩個次單元以非共價結合的方式形成的異分子雙體蛋白，其次單元分子量分別為70千道耳吞和80千道耳吞。現在已知當DNA在紫外光或自由基反應下產生末端的斷裂，Ku蛋白可以和雙股斷裂的DNA末端結合，並參與DNA雙股斷裂的修補。最近的研究發現在高等植物阿拉伯芥中也發現Ku70和Ku80的同源基因，而且它們的功能與哺乳動物中的Ku相類似。比較不同的地方在於動物細胞中Ku基因是持續性的表現，而且表現量很高，而在阿拉伯芥中Ku基因雖然在很多組織都有表現，但普遍表現量卻非常低。另外也有研究指出在植物發育的時候，Ku基因的表現會有增高的現象。
然而到目前為止，並沒有報告針對植物體中Ku基因如何被調控進行研究。為了探討Ku基因在植物體中的調控機制，我們在阿拉伯芥中篩選了Ku70 和Ku80的啟動子序列，利用生物資料庫分析得到在阿拉伯芥Ku基因的啟動子區域存在許多與抗壓性　（抗熱、抗冷、抗乾、抗組織受傷等）和荷爾蒙　（離層酸、乙烯、吉貝素）有關之序列。另外我們亦發現阿拉伯芥Ku70和Ku80啟動子上有一些重複性的序列區域，我們相信這些重複性序列應該和啟動子的功能活性有密切的關係。另一方面，我們將阿拉伯芥Ku70啟動子序列切割成不同長度的片度並將其結合在報導基因 (GUS reporter gene) 上游，並使用基因槍將此重組過的DNA質體送入洋蔥組織中，借以測試啟動子的活性是否因而改變。結果顯示，阿拉伯芥Ku70基因啟動子上的重複性序列被去除後，Ku70基因的表現確實有顯著的降低，可見此序列確實對Ku70基因的表現有重要影響。另外也利用不同荷爾蒙處理來找出啟動子片段上與各荷爾蒙相關的片段位置。

Ku protein is firstly defined as an autoantigen in sera from patients with autoimmune disease. It has been well known that Ku protein can bind double strand break ends and involve in double-strand break (DSBs) repair. Ku70 and Ku80 form a heterodimer during non-homologous end joining (NHEJ). Recently, Ku70 and Ku80 have been identified in Arabidopsis thaliana and their functions are similar to those in mammalian cells. The expression of Ku gene is constitutively at high levels in mammalian cell, although several studies indicate that the expression of Ku is dependent upon an entry into the cell cycle. However, AtKu gene is expressed widely, but at low level in plant tissues, and is probably induced during plant development. Nevertheless, there is no report on how AtKu genes are regulated in plants. In this study, we isolated promoter regions of AtKu70 and AtKu80. From database, we predicted several stress, hormone responsive elements, and repeat regions on AtKu promoters. We established several deletions constructs of AtKu70 promoter and used bombardment method to observe how the constructs work under different treatments and identify several important segments relative to AtKu70 expression.

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