Effect of the <i>CTNND2</i> G810R mutation on intracellular distribution of δ-catenin and Aβ secretion in HEK293 cells stably expressing human APP with the Swedish mutation (APP_sw).

<p><b>A.</b> HEK293 APP_sw cells were transfected with empty vector, wild type delta-catenin or G810R mutant delta-catenin (n = 3 each). Effect of G810R on cell morphology. In contrast to wild type δ-catenin, mutant δ-catenin is predominantly located at/under the cell surface and G810R mutant cells show a more elaborate network of protrusions (white arrows), suggesting that it may be altering interactions of the plasma membrane with the underlying actin cytoskeleton. Lower panels show detail for apical segments (red rectangles) at a higher magnification. <b>B.</b> Semi-quantitative analysis shows significantly more protrusions extending from apical segments in cells with G810R mutation (p = 0.006). Error bars represent the standard deviation. <b>C.</b> Effect of G810R on Aβ secretion. Conditioned media was collected at 16 hours and assayed for Aβ_1–40 and Aβ_1–42. Aβ concentrations were corrected for total protein levels. Error bars represent the standard deviation. When compared to empty vector controls, wild type δ-catenin had no effect on secreted Aβ levels. In contrast, cells expressing mutant δ-catenin displayed a significant and specific increase in the secretion of Aβ_1–42 (p = 0.02).