(A–B) HeLa-MZ cells were transfected with plasmids encoding wild-type or a S9A mutant of GSK3B 24 hr before the addition of Wnt-3a- or control-conditioned media (CM) for a further 24 hr. Cells were fixed, labeled with BODIPY (lipid droplets, green) and Hoechst 33342 (nuclei, magenta), and imaged by light microscopy. In (B) the number of lipid droplets was quantified by automated microscopy (bar graph), and the data are presented as the mean number of lipid droplets per cell of five independent experiments ± SEM, normalized to the control condition. (C–D) As in (A), except that HeLa-MZ cells (C) or L Cells (D) were transfected with siRNAs against the indicated targets for 48 hr, before the addition of Wnt3a. Efficient silencing was confirmed by qPCR (Figure 1—figure supplement 1B) and the data are presented as the mean number of lipid droplets per cell of 3 independent experiments ± SEM, normalized to the control condition. (E) L cells were incubated with the indicated compounds together with Wnt3a for 24 hr, processed and analyzed as in (A) and the data are presented as the mean number of lipid droplets per cell of five independent experiments ± SEM, normalized to the control condition. (F) Evolutionary relationship of the 19 Wnt ligands. Color indicates ability to induce lipid droplets as detailed in (G). (G) L Cells were transfected with plasmids containing each of Wnt ligand for 48 hr, imaged and analyzed as in (A). Data are normalized to the empty vector control and were tested for significance and are presented as the mean number of lipid droplets per cell of two independent replicates of the screen ± SEM, normalized to the control condition. The data are color-coded from a high (light) to a low (dark) number of lipid droplets induced by each Wnt ligand. (H–I) High-content image-based screen of a library of compounds that affect the Wnt pathway in HeLa-MZ cells. Cells were incubated for 24 hr with Wnt-3a- or control-conditioned media for 24 hr in the presence of the compounds at 1 µM and 10 µM, fixed, labeled with BODIPY (lipid droplets) and Hoechst 33342 (nuclei) and imaged by automated microscopy. The number of droplets per cell was counted and the zscores established, in order to quantify the ability of each compounds to induce lipid droplets in untreated cells (H, left panel), or to inhibit lipid droplet formation in Wnt3a-treated cells (H, right panel). Panel I illustrates the effects of compounds that induce droplet formation (left column) or that do (Trichostatin A) or do not (niclosamide, hexachlorophene) inhibit droplet formation (right column) in Wnt3a-treated cells. Nuclei are in magenta, and lipid droplets in green. Green bars, control-conditioned media (control CM); Red bars, Wnt3a-conditioned media (Wnt3a CM). In this figure, pValues are indicate as: *,<0.05; **, <0.005, and n.s., not significant.