Abstract
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.