The research group of Jianxiang Liu report the biological function of NAC103 in a novel transcriptional regulatory cascade
The unfolded protein response (UPR) plays important roles in plant development, plant-pathogen interactions, as well as in plant adaptation to adverse environmental stresses. Previously bZIP28 and bZIP60 have been identified as the important UPR regulators for mitigating the endoplasmic reticulum (ER) stress in Arabidopsis (Arabidopsis thaliana). Here we report the biological function of NAC103 in a novel transcriptional regulatory cascade, connecting bZIP60 to the UPR downstream genes in Arabidopsis. The expression of NAC103 was induced by ER stress, which was completely abolished in the bZIP60 null mutant. A new ER stress responsive cis-element UPRE-III (TCATCG) on the NAC103 promoter was identified, and the trans-activation of UPRE-III by bZIP60 was reconstructed in both yeast cells and Arabidopsis protoplasts. The direct binding of bZIP60 to UPRE-III-containing DNA was also demonstrated in an Electrophoretic Mobility Shift Assay (EMSA). NAC103 formed homodimer in Y2H and BiFC assays. It had transcriptional activation activity and localized in the nucleus. Over-expression of NAC103 had pleiotropic effects on plant growth and induced several UPR downstream genes in Arabidopsis under normal growth condition. The activation of UPR gene promoters by NAC103 was also confirmed in the effector-reporter protoplast assays. Thus, our study establishes a new transcriptional regulatory cascade in which NAC103 relays ER stress signal from bZIP60 to UPR downstream genes through a newly identified ER stress cis-element UPRE-III and the transcriptional activation activity of its encoding protein NAC103.
After joining in the life school by the end of 2009, Dr. Jianxiang Liu had published many papers as corresponding author in The Plant Cell, The Plant Journal, Molecular Plant and other international academic journals papers.