Figure 2Western blot analysis showing the depletion of PEX1 and PEX14 and the normal processing of Shh protein in the PEX1−/− and PEX14−/− hTERT-RPE1 cell clones. GAPDH served as a loading control.Immunostaining with anti-PEX1 (red) or PEX14 (red), anti-PMP70 (green), anti-ninein (blue), and anti-acetylated tubulin (white) in wild-type, PEX1−/−, and PEX14−/− hTERT-RPE1 cells in quiescent G0 phase. Arrowheads indicate primary cilia. Scale bar, 10 μm. Quantification of the number of PMP70-positive peroxisomes per cell from (B). Peroxisome formation in PEX1−/− and PEX14−/− hTERT-RPE1 cells was significantly impaired compared with that of the parental cells (mean ± s.d.: ***p<0.001: one-way ANOVA with Tukey's HSD, n=3: 20-25 cells per experiment). Quantification of proportion of ciliated cells from (B). Ciliogenesis in PEX1−/− and PEX14−/− hTERT-RPE1 cells was not significantly altered compared with that of the parental cells (mean ± s.d.: one-way ANOVA with Tukey's HSD, n=3: 190-200 cells per experiment).Quiescent G0-phase wild-type, PEX1−/−, and PEX14−/− hTERT-RPE1 cells transfected with AcGFP1-tagged D4 as a cholesterol probe were immunostained with anti-pericentrin (white) and anti-acetylated tubulin (blue) antibodies. Cholesterol was stained with Filipin III (red). Arrows and arrowheads indicate primary cilia and cytosolic accumulations of AcGFP1-tagged D4, respectively. Scale bar, 5 μm. Quantification of the Filipin III intensity at primary cilia from (E). PEX1−/− and PEX14−/− hTERT-RPE1 cells had significant reductions in the ciliary signal of Filipin III (***p<0.001: one-way ANOVA with Tukey's HSD, n=3: 40-50 cells per experiment). In the boxplot, medians, 25th/75th percentile and min/max were represented by the central lines, the box limits, and the whiskers/error bars, representatively. Quantification of the AcGFP1-tagged D4 intensity at primary cilia from (E). The ciliary signal of AcGFP1-tagged D4 in PEX1−/− and PEX14−/− hTERT-RPE1 cells was significantly diminished (***p<0.001: one-way ANOVA with Tukey's HSD, n=3: 25-30 cells per experiment). In the boxplot, medians, 25th/75th percentile and min/max were represented by the central lines, the box limits, and the whiskers/error bars, representatively.Quiescent G0-phase wild-type, PEX1−/−, and PEX14−/− hTERT-RPE1 cells were treated with or without 1.5% methyl-β-cyclodextrin for 45 min, and then incubated with or without cholesterol (cholesterol/methyl-β-cyclodextrin complex) for 1 h. After removing exogenous cholesterol, they were stimulated with 50 nM Shh-N for 24 h in the presence of pravastatin, and then immunostained with anti-Smo (green), anti-acetylated-tubulin (blue), and anti-γ-tubulin (red) antibodies. For the alternative cholesterol complementation, LDL (0.06 mg/ml) was co-incubated with Shh-N and pravastatin for 24 h after methyl-β-cyclodextrin-mediated cholesterol depletion. Scale bar, 2.5 μm. Quantification of the Smo intensity at primary cilia in wild-type, PEX1−/−, and PEX14−/− hTERT-RPE1 cells from (H). PEX1−/− and PEX14−/− hTERT-RPE1 cells exhibited the dampened Shh-N ligand-induced ciliary accumulation of Smo. The complementation of exogenous cholesterol (cholesterol/methyl-β-cyclodextrin complex) restored the ciliary accumulation of Smo in both PEX-knockout cells, while the LDL complementation did not rescue the ciliary phenotypes efficiently (*p<0.05, **p<0.01, ***p<0.001: one-way ANOVA with Tukey's HSD, n=3: 90-100 cells per experiment). In the boxplot, medians, 25th/75th percentile and min/max were represented by the central lines, the box limits, and the whiskers/error bars, representatively.