Role of N-Cadherin <i>cis</i> and <i>trans</i> Interfaces in the Dynamics of Adherens Junctions in Living Cells

<div><p>Cadherins, Ca²⁺-dependent adhesion molecules, are crucial for cell-cell junctions and remodeling. Cadherins form inter-junctional lattices by the formation of both <i>cis</i> and <i>trans</i> dimers. Here, we directly visualize and quantify the spatiotemporal dynamics of wild-type and dimer mutant N-cadherin interactions using time-lapse imaging of junction assembly, disassembly and a FRET reporter to assess Ca²⁺-dependent interactions. A <i>trans</i> dimer mutant (W2A) and a <i>cis</i> mutant (V81D/V174D) exhibited an increased Ca²⁺-sensitivity for the disassembly of <i>trans</i> dimers compared to the WT, while another mutant (R14E) was insensitive to Ca²⁺-chelation. Time-lapse imaging of junction assembly and disassembly, monitored in 2D and 3D (using cellular spheroids), revealed kinetic differences in the different mutants as well as different behaviors in the 2D and 3D environment. Taken together, these data provide new insights into the role that the <i>cis</i> and <i>trans</i> dimers play in the dynamic interactions of cadherins. </p>