Use of photoactivation and photobleaching to monitor the dynamic regulation of E-cadherin at the plasma membrane.

The dynamic control of E-cadherin is critical for establishing and maintaining cell-cell junctions in epithelial cells. The concentration of E-cadherin molecules at adherens junctions (AJs) is regulated by lateral movement of E-cadherin within the plasma membrane and endocytosis. Here we set out to study the interplay between these processes and their contribution to E-cadherin dynamics. Using photoactivation (PA) and fluorescence recovery after photobleaching (FRAP) we were able to monitor the fate of E-cadherin molecules within the plasma membrane. Our results suggest that the motility of E-cadherin within, and away from, the cell surface are not exclusive or independent mechanisms and there is a fine balance between the two which when perturbed can have dramatic effects on the regulation of AJs.