Liu Pei Feng, Chang Wen Chi, Wang Yung Kai, Chang Hwan You, Pan Rong Long
Department of Life Sciences, National Tsing Hua University, Hsin Chu, Taiwan 30043, Republic of China.
Biochim Biophys Acta. 2008 Mar;1779(3):164-74. doi: 10.1016/j.bbagrm.2007.12.005. Epub 2007 Dec 15.
The Ku heterodimer facilitates the regulation of DNA repair, DNA replication, cell cycle, and telomere maintenance. The plant hormone abscisic acid (ABA) is a plant growth inhibitor. This study investigates how Arabidopsis thaliana Ku (AtKu) genes are regulated by ABA in 3-week-old seedlings. First, beta-Glucuronidase assay and real time quantitative PCR analysis results indicate that ABA represses the AtKu gene in a time- and concentration-dependent manner. However, adding of ABA biosynthesis inhibitors, fluride and tungate, did not eliminate AtKu suppression. Moreover, analysis of inhibitor treatments and ABA-responsive mutants suggested that AtKu repression by ABA was mediated through the pathway of extracellular Ca(2+), phospholipase D alpha, p38-type mitogen-activated protein kinase (MAPK), MAPK6 and ABA transcription factors, ABI3 and ABI5. Finally, no cross-talk in modulating AtKu gene expression existed between ABA and antagonist hormones (auxins and gibberellic acid).
Ku异二聚体有助于调节DNA修复、DNA复制、细胞周期和端粒维持。植物激素脱落酸（ABA）是一种植物生长抑制剂。本研究调查了3周龄拟南芥幼苗中AtKu基因是如何受ABA调控的。首先，β-葡萄糖醛酸酶分析和实时定量PCR分析结果表明，ABA以时间和浓度依赖性方式抑制AtKu基因。然而，添加ABA生物合成抑制剂氟化物和钨酸盐并不能消除对AtKu的抑制作用。此外，对抑制剂处理和ABA反应突变体的分析表明，ABA对AtKu的抑制是通过细胞外Ca(2+)、磷脂酶Dα、p38型丝裂原活化蛋白激酶（MAPK）、MAPK6以及ABA转录因子ABI3和ABI5的途径介导的。最后，在调节AtKu基因表达方面，ABA与拮抗激素（生长素和赤霉素）之间不存在相互作用。
