Figure 4.

Lung progenitor cultures generated from iPSCs from three different donors with the nonsense mutation W1282X exhibit differential phenotypic responses to modulators

(A) Heatmap of peak responses generated from non-CF culture stimulated with 10 μM forskolin (FSK) (left) and CF culture (W1282X) treated with a combination of small molecules (A–H, concentrations defined in Table S1; see also Video S1 for movie showing dynamic CFTR activation in the assay).

(B) Bar graph showing the peak response of W1282X CFTR treated with DMSO (0.1%) or small molecules (defined on y axis with concentrations indicated in Table S1). After a 5 min baseline, the cells were stimulated with DMSO or FSK ± 1 μM VX-770 (VX) or 1.5 μM AP2 (AC). Mean peak responses (of 4 wells in a 96 well plate) after agonist and potentiator are shown for each small-molecule combination as a solid circle. The horizontal line in each bar, indicates the range amongst the mean measurements. Three patients homozygous for W1282X were studied (CF5, 6, and 7). For CF5, 5 plates generated from four differentiations from iPSCs were studied. For CF6, 3 plates from one differentiation were studied, and for CF7, 5 plates from two differentiations were studied. CFTR modulators (VX-809 or AC1 + AC2-2), in combination with SMG1i, were effective in increasing the abundance of the truncated W1282X protein in lung progenitor cultures (Figure S4).

(C) Correlation plot between FLIPR peak response and Ussing chamber studies (data from Laselva et al., 2020a).

(D) Basal W1282X-CFTR transcript (left) expression in primary nasal epithelial cultures (nasal) and submerged iPSC-derived lung progenitor cultures (SC) from three donors. The vertical line in each bar shows the range in CFTR expression amongst the three donors.