Functional regulation of Slug/Snail2 is dependent on GSK-3β-mediated phosphorylation.

Snail family proteins regulate transcription of molecules for cell-cell adhesion during epithelial-mesenchymal transition (EMT). Based on putative glycogen synthase kinase 3β (GSK-3β) phosphorylation sites within the Slug/Snail2, we explored the significance of GSK-3β-mediated phosphorylation in Slug/Snail2 expression during EMT. Mutation of the putative GSK-3β phosphorylation sites (S92/96A or S100/104A) enhanced the Slug/Snail2-mediated EMT properties of E-cadherin repression and vimentin induction, compared with wild-type Slug/Snail2. S92/96A mutation inhibited degradation of Slug/Snail2 and S100/104A mutation extended nuclear stabilization. Inhibition of GSK-3β activity caused similar effects, as did the phosphorylation mutations. Thus, our study suggests that GSK-3β-mediated phosphorylation of Slug/Snail2 controls its turnover and localization during EMT.