Insufficiency of ciliary cholesterol in hereditary Zellweger syndrome (2020)
Figure 3

Figure 3 Peroxisomes accompanied by cholesterol move along the microtubules to interact with the ciliary pocket structure

(A) Quiescent G0-phase hTERT-RPE1 cells were immunostained with anti-PEX14 (red), anti-ninein (white), and anti-acetylated tubulin (blue) antibodies. Cholesterol was stained with Filipin III (Green). Magnified images of the boxed regions showing peroxisome accompanied by cholesterol (arrows). Three-dimensional reconstitution of the same cell indicates that Filipin III stains the membrane regions of ciliary axonemes and peroxisomes. The scale bars indicate 2.5 μm and 1.25 μm in lower- and higher-magnified images, respectively.

(B) Quiescent G0-phase wild-type hTERT-RPE1 cells treated with Cytochalasin-D (200 nM), colcemid (50 nM), or Ciliobrevin-D (10 μM) for 6 h were immunostained with anti-ARL13B (blue), anti-phospho-S473-Akt (red), anti-ninein (green), and anti-PMP70 (white) antibodies. Arrows indicate the peroxisomes interacting with the ciliary pocket. Scale bar, 5 μm.

(C) Quantification of proportion of primary cilia interacting with peroxisomes from (B). Colcemid (50 nM) and Ciliobrevin-D (10 μM) significantly inhibited the spatial interaction between peroxisomes and primary cilia (mean ± s.d.: ***p<0.001: one-way ANOVA with Tukey's HSD, n=3: 45-50 cells per experiment).

(D) Quiescent G0-phase wild-type hTERT-RPE1 cells were treated with Cytochalasin-D (200 nM), Colcemid (50 nM), or Ciliobrevin-D (10 μM) for 6 h and then immunostained with anti-acetylated tubulin (blue) and anti-pericentrin (green) antibodies. Cholesterol was stained with Filipin III (green). Arrows indicate primary cilia. Scale bar, 2.5 μm.

(E) Quantification of the Filipin III intensity at primary cilia from (D). Colcemid and Ciliobrevin-D interfered with the distribution of cholesterol in the ciliary membrane (***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.

(F) hTERT-RPE1 cells were transfected with AcGFP1-tagged EHD3 and cultured without serum for 24 h before immunostaining with anti-GFP (green), anti-ARL13B (blue), anti-PMP70 (white), and anti-phospho-S473-Akt (red) antibodies. The scale bars represent 2.5 μm.

(G) 3×FLAG-tagged EHD1 or EHD3 and AcGFP1-tagged PEX14 were coexpressed in HEK293T cells and then immunoprecipitated from whole-cell lysates using the anti-FLAG antibody. AcGFP1-tagged PEX14 and 3×FLAG-tagged EHD1 or EHD3 fragments in the IP fractions and inputs were detected by western blotting.

(H) Recombinant GST (0.2 μg) or GST fused to PEX14 proteins (1 μg) and 6×His-EHD3 protein (1 μg) were pulled down using glutathione-Sepharose beads. GST-tagged PEX14 and 6×His-tagged EHD3 proteins in the pull-down fractions and inputs were detected by western blotting.

(I) 3D reconstitution of the quiescent G0-phase hTERT-RPE1 cells transfected with AcGFP1-tagged EHD3 (white) immunostained with anti-acetylated-tubulin (blue) and anti-PEX14 (red) antibodies. Cholesterol was stained with Filipin III (green). Cholesterol-containing peroxisome interacted with the ciliary pocket (arrow). The scale bars indicate 2 μm.