Figure 1.

The regulation of Ecad-mediated intercellular adhesion at single-molecule resolution. (A) Schematic of the methodology used to measure Ecad/Ecad bond strength between adjoining live cells at single-molecule resolution. An AFM loaded with living cells is brought into contact with cells plated on uncoated or ECM-coated dishes. The cartoon on the right depicts the central question investigated in this work: how do changes in intracellular β-catenin and changes in extracellular ECM affect intercellular adhesion via modulation of single Ecad/Ecad bond strength. (B) Representative force-displacement curves obtained during the controlled retraction of the AFM cantilever at a speed of 20 μm/s. Red arrows mark bond rupture events; the height of the fall corresponds to the bond strength expressed in pico-Newton. Green arrows mark multiple rupture events. Only the last bond rupture was counted toward the determination of mean bond strength. (C) Distribution of occurrence of single and multiple rupture events followed Poisson statistics, shown for HCT116 cells expressing only WT (β^WT/−), only ΔS45 β-catenin (β^−/Δ45), and with β-catenin depleted (β^WT/−(KD)). (D) The frequency of bond rupture with and without function-blocking antibody, together showing that the recorded rupture events predominantly reflect the rupture of Ecad/Ecad bonds. All error bars designate SEM.