Fig. 6: Oncogenic APC alters interactions between Wnt receptors and their effectors.

To examine the effect of oncogenic APC on interactions between Wnt receptors and key lipids, cells co-expressing EGFP-tagged A, C Fzd7 or B, D LRP6 and mCherry-tagged A, B D4H or C, D pleckstrin homology (PH) ___domain of phospholipase C δ1 (PLC-δ1, PI(4,5)P₂ sensor) were used to perform FLIM FRET. E To examine the effect of oncogenic APC on PI(4,5)P₂ plasma membrane levels, cells expressing EGFP-tagged PLC-δ1-PH were used to measure membrane-associated EGFP fluorescence intensity using flow cytometry. EGFP plasma membrane fluorescence intensity was normalized to total EGFP fluorescence intensity. To examine the effect of oncogenic APC on the interactions between Dvl1 and key lipids, cell co-expressing EGFP-tagged F, G Dvl1 and mCherry-tagged F D4H or G PLC-δ1 were used to perform FLIM FRET. YAMC, IMCE, and IMCE βcat cells were pre-treated with mevastatin (5 µM, 24 h), MβCD (10 mM, 30 min), or phenylarsine oxide (PAO) (20 µM, 30 min) and washed, as indicated. Subsequently, cells were incubated with Wnt3a-conditioned media or control media without Wnt3a for 30 min, washed, fixed, and imaged. For FLIM-FRET experiments, the apparent FRET efficiency was calculated from FLIM data averaged per FOV (mean ± SD, n = 10–15 FOVs containing 3–8 cells were examined per condition, exact n value is shown in each graph). For flow cytometry IL PI(4,5)P₂ experiments, cells were imaged to calculate EGFP fluorescence intensity (mean ± SEM, from n = 3 independent biological replicates, total number of cells analyzed is provided below each bar). For all experiments, statistical significance was determined by two-way ANOVA and post Tukey’s multiple comparison test. Different letters indicate significant differences between WT APC (control) and mutant APC/treatment groups (experimental) (P < 0.05). Source data are provided as a Source data file.