Subcellular localization of VIP1 is regulated by phosphorylation and 14-3-3 proteins

Arabidopsis basic leucine zipper transcription factor VIRE2-interacting protein 1 (VIP1) changes its localization from the cytosol to the nucleus when cells are subjected to mechanical or hypo-osmotic stress, although the mechanism of this change is not known. In this study, we show that change in VIP1 subcellular localization is synchronized with a change in the VIP1 phosphorylation state that is induced by mechanical/hypo-osmotic stress. VIP1 has three phosphorylatable serine residues in HXRXXS motifs, which are 14-3-3-binding targets. Mutations of these residues results in the lack of 14-3-3 binding and prevents cytosolic localization of VIP1. These results suggest that dephosphorylation of VIP1 resulting from mechanical or hypo-osmotic stress induces nuclear localization via 14-3-3 dissociation.