During morphogenesis junctions between epithelial cells are rapidly assembled and disassembled in order to allow cell movements and shaping of organs and tissues. We found that dynamic post-translational modifications and specifically the SUMO machinery play a role in the regulation of the flexibility of cell junctions during Caenorhabditis elegans epidermal morphogenesis. We identified the SUMO protease ULP-2 as a regulator of adherens junctions (AJ) assembly and show that dysregulated ULP-2 activity impairs epidermal morphogenesis in C. elegans embryos. The conserved cytoplasmic tail of HMR-1/E-cadherin is sumoylated and is a target of ULP-2 desumoylation activity. Coupled sumoylation and desumoylation of HMR-1 are required for its recruitment to the subapical membrane during AJ assembly and the formation of the linkages between AJs and the apical actin cytoskeleton. Sumoylation weakens HMR-1 binding to HMP-2/β-catenin. Our study provides a mechanistic link between the dynamic nature of the SUMO machinery and AJs plasticity and highlight sumoylation as a molecular switch that modulate the binding of E-cadherin to the actin cytoskeleton. We are currently studying how ULP-2 activity is regulated during epidermal morphogenesis.