Differential regulation of Ku gene expression in etiolated mung bean hypocotyls by auxins.
Plant Ku genes were identified very recently in Arabidopsis thaliana, and their roles in repair of double-stranded break DNA and maintenance of telomere integrity were scrutinized. In this study, the cDNAs encoding Ku70 (VrKu70) and Ku80 (VrKu80) were isolated from mung bean (Vigna radiata L.) hypocotyls. Both genes were expressed widely among different tissues of mung bean with the highest levels in hypocotyls and leaves. The VrKu gene expression was stimulated by exogenous auxins in a concentration- and time-dependent manner. The stimulation could be abolished by auxin transport inhibitors, N-(1-naphthyl) phthalamic acid and 2,3,5-triiodobenzoic acid implicating that exogenous auxins triggered the effects following their uptake by the cells. Further analysis using specific inhibitors of auxin signaling showed that the stimulation of VrKu expression by 2,4-dichlorophenoxyacetic acid (2,4-D) was suppressed by intracellular Ca(2+) chelators, calmodulin antagonists, and calcium/calmodulin dependent protein kinase inhibitors, suggesting the involvement of calmodulin in the signaling pathway. On the other hand, exogenous indole-3-acetic acid (IAA) and alpha-naphthalene acetic acid (NAA) stimulated VrKu expression through the mitogen-activated protein kinase/extracellular signal-regulated kinase pathway. Altogether, it is thus proposed that 2,4-D and IAA (or NAA) regulate the expression of VrKu through two distinct pathways.
Liu
Pei-Feng
PF
Department of Life Sciences and Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsin Chu, Taiwan 30043, Republic of China.
Chang
Wen-Chi
WC
Wang
Yung-Kai
YK
Munisamy
Suresh-Babu
SB
Hsu
Shen-Hsing
SH
Chang
Hwan-You
HY
Wu
Shu-Hsing
SH
Pan
Rong-Long
RL
D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D003624:Darkness; D007887:Fabaceae / Q000187:drug effects / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000502:physiology*; D007210:Indoleacetic Acids / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009280:Naphthaleneacetic Acids / Q000494:pharmacology; D010940:Plant Proteins / Q000096:biosynthesis*; D016415:Sequence Alignment
D004268:DNA-Binding Proteins; D007210:Indoleacetic Acids; D009280:Naphthaleneacetic Acids; D010940:Plant Proteins; D015084:2,4-Dichlorophenoxyacetic Acid; C034182:1-naphthaleneacetic acid; C030737:indoleacetic acid