EMBO/SourceData huggingface dataset:
Figure 2B, C The immunoprecipitation analysis. Co-precipitation was impaired by either the WW domain deletion of ITCH or the mutation in the PPxY motifs of ENTREP. Data shown are representative of at least two independent experiments. IP, immunoprecipitation; IB, immunoblot.E Representative images of the proximity ligation assay (PLA) using Cos7 cells transfected with indicated vectors. PLA signals, granular dots of green color, were presented with DAPI images. Arrowheads, the plasma membrane. Scale bar, 10mm. F The box-and-whisker plot presentation of the PLA. A minimum of 10 cells per condition were counted from two independent experiments. P-values obtained by Student's t-tests and P < 0.05 was considered as statistically significant. * P < 0.05. Box-whisker plot represents the interquartile range (25th and 75th percentiles) as a box and the median as a line. The maximn and minimun values within 1.5 x interquartile range are shown as whiskers.
Figure 3A The nickel-pull down assay using myc/HIS-tagged ENTREP along with HA-tagged ubiquitin. Arrows indicate HA-ubiquitin-incorporating ENTREP. Arrowhead indicates ENTREP without ubiquitination. Data shown are representative of three independent experiments.
Figure 4A The immunoprecipitation analysis. The cytoplasmic ENTREP (wild or mut1+2 mutant) co-precipitated with EPN1myc in the presence of ITCH wild or C830A. The blot bands were semi-quantified using ImageJ software. ENTREP ratio was caluculated as a ratio of ENTREP in the myc-coprecipitaed sample to that of the total lysate. The ratios shown as mean ± SD from three biological replicates. P-values were obtained by Student's t-tests and P < 0.005 was considered as statistically significant. No significant difference was observed.B Representative images of the proximity ligation assay (PLA) using Cos7 cells transfected with indicated vectors. PLA signals, granular dots of green color, were presented with DAPI images. Scale bar, 10mm. C The box-and-whisker plot presentation of the PLA. A minimum of 10 cells per condition were counted from two independent experiments. P-values obtained by Student's t-tests and P < 0.05 was considered as statistically significant. * P < 0.05. Box-whisker plot represents the interquartile range (25th and 75th percentiles) as a box and the median as a line. The maximn and minimun values within 1.5 x interquartile range are shown as whiskers.
Figure 5B The immunoprecipitation analysis. Cytoplasmic ENTREP co-precipitated with either ITCH C830A, delWW12 or delWW34 but not with delWW14. Data shown are representative of at least two independent experiments. C The immunoprecipitation analysis. HA-CXCR4SS-DsRed hardly co-precipitated with either ITCHC830A or delWW mutants. HA-CXCR4DD-DsRed co-precipitated with ITCH C830A and delWW12 but not with delWW14 and delWW34. Data shown are representative of at least two independent experiments.F The nickel-pull down assay using indicated vectors along with HISx6-tagged wild type ubiquitin vector. HA-tagged DsRed was used as a control for HA-CXCR4DD-DsRed. Arrowhead, FLAG-tagged ITCH (wild or C830A); arrow, FLAG-ENTREP wild cyt. Data shown are representative of at least two independent experiments. G Co-localization of ENTREP and CXCR4 in the endosome. Cos7 cells were transfected with ENTREP-FLAG, CXCR4-DsRed and Halo-ITCH wild vectors and treated with CXCL12. ENTREP-FLAG and CXCR4-DsRed co-localized in the RAB7-positive endosome. Inserts, the high-magnification images of the marked area indicating the colocalizaion of ENTREP-FLAG, CXCR4-DsRed and RAB7. Scale bar 10mm. The image is representative of at least two independent experiments.
Figure 6C The expression of endogenous CXCR4 in lentivirally-transduced MCF-7 ENTREP-KO cells. CXCL12 (+) and (-) indicate the presence and absence of CXCL12 treatment. In CXCL12-treated ENTREP-EGFP expressing cells, a non-negligible amount of CXCR4 was observed in the cytoplasm, in which CXCR4 was overlapped with ENTREP-EGFP. CXCR4 expression on the cell surface still remained (arrows). Scale bar 10 mm. The images are representative of at least three independet experiments.
Figure 7A Dot plot presentation of the chemotaxis analyses using the Boyden chamber. CXCL12 (+) and (-) indicate the presence and absence of CXCL12 as an attractant in the bottom chambers. ENTREP-knockout enhanced the chemotaxis toward CXCL12, which was blocked by pre-treatment with AMD3100 (upper panel). The doxycyclin (DOX)-induced ENTREP expression suppressed the chemotaxis of mouse 4T1-Luc cells toward CXCL12 (lower panel). Ratio of migrated cells into the bottom chamber against the applied cells on the top chambers was normalized by the results of non-treated cells (n=7, upper panel, and n=9, lower panel, from at least two independent experiments, respectively). P-values were obtained by Student's t-tests and P < 0.005 was considered as statistically significant. Insert, the immunoblot analysis of the DOX-induced ENTREP expression in 4T1-Luc cells. NS, not significant.B Dot plot presentation of mammosphere assay (left panel) and the images of mammosphere (right panel). Each mark in dot plot presentation indicates the number of mammosphere from 3,000 cells per well in an ultra-low attachment plate from two independent experiments. To estimate the effect of CXCL12/CXCR4 pathway, 100 ng/ml of CXCL12 and 12 μM of AMD3100 were applied as indicated. For statistical analysis, variance was assessed using two-way ANOVA and significance was calculated using Tukey post hoc test correcting for multiple comparison. NS, not significant. Scale bar in the images of mammosphere 100 mm.
Figure 1C Co-crystal structure of gephyrin E-domain (blue) and bound GlyR ß-loop (red - PDB code 2FTS (Kim et al., 2006)). The mutated gephyrin Gly375 residue is shown in orange.
Figure 2A Representative images of GFP-gephyrin and GFP-G375D, expressed in hippocampal neurons at 9 + 4 days in vitro. Inset shows higher magnification. Scale bar = 20 µm.B Relative distribution of cluster density of gephyrin variants on dendrites from transfected neurons. Number of gephyrin clusters in each dendrite is normalized to 20 µm segments.C Representative segments of dendrites expressing GFP-gephyrin or GFP-G375D and immunostained with the presynaptic marker VGAT. Arrowheads show co-localization of gephyrin and VGAT clusters. Scale bar = 10 µm.D Quantification of co-localization between gephyrin and VGAT clusters (gephyrin-VGAT 77.4±2.9 %, G375D-VGAT 30±4.4 %). 31 GFP-gephyrin and 30 GFP-G375D neurons from three independent cultures were used for quantifications. Results are expressed as mean ± SEM
Figure 4A Representative neurons expressing myc-tagged gephyrin or G375D and pHluorin-tagged GABAAR γ2. Surface-expressed γ2-subunits were immunolabelled with GFP-antibodies in red, and the pHluorin-fluorescence (total γ2 levels) are shown in green.B Size and C fluorescence (fl.) intensity of surface-expressed γ2 clusters in myc-gephyrin and myc-G375D-expressing dendrites (n = 20 myc-gephyrin and 21 myc-G375D neurons in B and 18 myc-gephyrin and myc-G375D neurons in C)D Mean γ2-pHluorin fluorescence in myc-gephyrin and myc-G375D-expressing dendrites (n = 20 and 18 myc-gephyrin and myc-G375D expressing neurons).E Number of surface γ2 clusters on dendrites normalized to 20 µm segments (n = 18 myc-gephyrin and myc-G375D expressing neurons). At least three independent cultures were used for each experiment. Results are expressed as mean ± SEM; Data were analyzed by t-test.F Representative traces of miniature recordings on cultured hippocampal neurons transfected either with GFP-gephyrin or GFP-G375D.G mIPSC amplitudes from neurons expressing GFP-gephyrin or GFP-G375D. Numbers show analyzed cell-numbers. Data were analyzed by one-way ANOVA and post-hoc Tukey test.H Frequency of the mIPSCs from neurons expressing GFP-gephyrin or GFP-G375D. The horizontal line within the boxes indicates the median frequency for the represented condition (bottom/top boundary indicates the 25th /75th percentile). Top and bottom error bars indicate the 90th and 10th percentiles, respectively. Analysis by Kruskal-Wallis test followed by post-hoc Mann-Whitney test.
Figure 5A Western blot of HEK293 cells expressing GFP-tagged gephyrin or G375D using GFP-specific and polyclonal gephyrin antibodies. Note that both gephyrin variants are stably expressed and show no degradation in the cells. Asterisk in the poly-gephyrin blot shows endogenous gephyrin.B SDS-PAGE of E. coli expressed and purified 6His-gephyrins and CD spectra. Mean residue ellipticity of gephyrin and G375D show profiles with minima at 208 nm and 222 nm.C Size-exclusion chromatography of purified 6His-gephyrin and isolated E-domain variants. Full-length gephyrins and isolated E-domains were loaded onto a Superose 6 gel filtration column and elution of the protein was monitored by measuring absorbance at 280 nm (mAU, milliabsorbance units).D Co-immunoprecipitation of HEK293 cell lysates expressing myc-tagged gephyrin together with GFP-tagged gephyrin or G375D using myc-specific antibodies. Control IgG were used to show specificity of the assay.
Figure 6B Representative pulldown-experiment and quantification of 6His-tagged gephyrin and G375D using immobilized α3-peptide. 6His-tagged gephyrin variants were expressed in E. coli cells, purified to homogeneity and incubated with α3-peptides immobilized to NeutrAvidin beads. n = 3, normalized to 6His-gephyrin. 38.9±1.5% G375D were pulled down.C Representative SPR sensograms of 6His-gephyrin and 6His-G375D binding to immobilized GABAAR α3-peptide. Response units are plotted against time. Injected gephyrin concentrations were 0.5, 2, 10, 25, 40 µM.D SPR binding isotherms of a representative experiment as in C. Calculated KD values of 3.2 and 10 µM for gephyrin and G375D, respectively, are indicated by vertical lines. The experiment was repeated three times with two independently purified protein batches and two sensor chips.E Representative ITC binding isotherms of the cytoplasmic loop of the GlyR ß-subunit (GlyR-ßL, residue 378-426) and 6His-tagged gephyrin or G375D. The GlyR-ßL-gephyrin binding data (black) were fitted in a two-side model, whereas G375D binding could only be fitted to a single binding site. Dissociation constants KD and stoichiometry (N = number of binding sites) are given for each binding component. n = 5 from two independently purified protein batches. Results are expressed as mean ± SEM.
figf1(b) Parkin is recruited selectively to depolarized mitochondria and directs mitophagy. HeLa cells transfected with HA-Parkin were treated with CCCP for the indicated times. Mitochondria were stained by anti-TOM20 (pseudo coloured; blue) and a ΔΨm dependent MitoTracker (red). Parkin was stained with anti-HA (green). Without treatment, mitochondria are intact and stained by both mitochondrial markers, whereas Parkin is equally distributed in the cytoplasm. After 2 h of CCCP treatment, mitochondria are depolarized as shown by the loss of MitoTracker staining. Parkin completely translocates to mitochondria clustering at perinuclear regions. After 24 h of CCCP treatment, massive loss of mitochondria is observed as shown by the disappearance of the mitochondrial marker. Only Parkin-positive cells show mitochondrial clustering and clearance, in contrast to adjacent untransfected cells. Scale bars, 10 μm.(c) Pathogenic Parkin mutations abrogate mitochondrial translocation and/or clearance. HeLa cells transfected with Flag-Parkin wild-type or pathogenic mutants were treated with CCCP and stained with anti-Flag (green), anti-TOM20 (red) and Hoechst33342 (blue). Representative merged images are shown. Scale bars, 10 μm. Immunostaining of cells transfected with non-functional cysteine mutants and functional Parkin variants is shown in Supplementary Information, Fig. S1a and S1b, respectively.(d, e) Based on the mitochondrial effects, Parkin mutants can be classified into functional and non-functional classes. (d) Quantification of Parkin translocation to damaged mitochondria after 2 h of CCCP treatment, as defined by complete colocalization of Parkin with the mitochondrial marker (n = 3). (e) Quantification of cells with uncleared mitochondria after 24 h of CCCP treatment, as shown by complete loss of mitochondrial staining (n = 3). Data represent the mean ± s.d., *P ≤ 0.05, **P ≤ 0.005, ***P ≤ 0.0005 compared with wild-type. WT, wild-type.
figf2Stable Parkin wild-type or pathogenic mutants expressing SH-SY5Y cell lines were induced with doxycycline (DOX) for 72 h and treated with CCCP for the indicated times. Cells were stained with anti-Parkin (green), anti-TOM20 (red) and Hoechst33342 (blue). (a-b) CCCP treatment of stable SH-SY5Y cells for 0 h. Unstimulated control cells (- DOX) show relatively low levels of endogenous Parkin, compared to cells with induced expression of Parkin wild-type or K161N, R275W and G430D mutants (+ DOX). Immunostaining (a) and western blot analysis (b) of the induced cells demonstrate comparable levels of Parkin expression in the selected clones. β-Actin served as a loading control.(c, d) After 2 h of CCCP treatment, massive colocalization of wild-type Parkin and mitochondrial clusters can be observed in the induced cells when compared with unstimulated controls. Similarly, Parkin K161N and R275W mutants translocate to mitochondria, whereas G430D does not.(e, f) After 24 h of CCCP treatment, induced wild-type Parkin-expressing cells show full clearance of damaged mitochondria. In contrast, the pathogenic mutants analysed fail to execute mitophagy and, therefore, damaged mitochondria remain uncleared. Representative images of three independent experiments are shown. Scale bars, 10 μm (a, c and e). (d, f) Quantifications of the observed mitochondrial effects in Parkin-expressing SH-SY5Y cells (n = 3). Data represent the mean ± s.d., ***P ≤ 0.0005 compared with induced wild-type Parkin. WT, wild-type.
figf3(b) Co-immunoprecipitations of Parkin and PINK1 after mitochondrial depolarization. Endogenous Parkin and PINK1 were co-immunoprecipitated from neuronal SH-SY5Y cells after CCCP treatment with specific antibodies.(c) Western blot of PINK1 siRNA-transfected HeLa cells used in d-h demonstrates the knockdown efficiency and specificity of PINK1 silencing.d-h) PINK1-specific siRNA abrogates Parkin translocation to mitochondria after 2 h, and mitochondrial clearance after 24 h, of CCCP treatment. This can be rescued by re-transfection with wild-type PINK1, but not with a kinase-dead mutant or a PINK1 variant lacking the MTS. Control siRNA- or PINK1 siRNA-silenced HeLa cells were transfected with EGFP-Parkin wild-type and PINK1-V5 wild-type, 3×KD or ΔMTS mutants. Use of appropriate empty vector controls is depicted. Cells were treated with CCCP and stained with anti-TOM20 (pseudo coloured; blue) and anti-V5 (red) to visualize mitochondrial morphology and re-transfected PINK1, respectively. Wild-type Parkin was visualized by EGFP epifluorescence (green). Parkin-positive cells are surrounded by a line. Representative images of four independent experiments are shown. Scale bars, 10 μm.(e) Wild-type Parkin colocalization with impaired mitochondria after 2 h of CCCP treatment was analysed (n = 4). (g) Quantification of results from cells in e.(f) Uncleared mitochondria were analysed after 24 h of CCCP treatment (n = 4). (h) Quantification of results from cells in f. Data represent the mean ± s.d., **P ≤ 0.005, ***P ≤ 0.0005 compared with control siRNA-transfected cells. Immunostaining of control siRNA-transfected cells at all analysed time points is shown in Supplementary Information, Fig. S2. WT, wild-type.
figf4a, b) Stable Mito-DsRed (pseudo coloured; blue)-expressing HeLa cells were transfected with Flag-Parkin wild-type or pathogenic mutants. Cells were treated with CCCP before immunostaining of Parkin with anti-Flag (green) and endogenous poly-ubiquitin with a specific antibody FK1 (red). (a) In contrast to pathogenic mutations, wild-type Parkin shows colocalization with poly-ubiquitin after 6 h of CCCP treatment at the site of condensed mitochondria. (b) After 24 h of CCCP treatment, K161N and R275W Parkin mutants colocalize with both poly-ubiquitin and mitochondria. In contrast, translocation-deficient Parkin mutants K211N, T240R and G430D lack the mitochondria-associated poly-ubiquitin signal. Representative images are shown. Scale bars, 10 μm. Complementary Parkin of untreated cells and quantification of colocalization of Parkin, mitochondria and poly-ubiquitin upon CCCP treatment are shown in Supplementary Information, Fig. S3a, b and c, respectively.(c, d) Parkin-directed mitophagy specifically involves linkage of ubiquitin through lysines 27 and 63. HeLa cells were transfected with EGFP-Parkin wild-type and ubiquitin lysine variants and treated with CCCP before immunostaining with anti-HtrA2/Omi, as a mitochondrial marker (pseudo coloured; blue) and anti-His (red) to detect ectopic ubiquitin. Parkin was visualized by its fusion to EGFP (green). (c) Note that only wild-type, K27 and K63 6×His-tagged ubiquitin variants are colocalized with condensed mitochondria and EGFP-Parkin after 6 h of CCCP treatment. All other ubiquitin mutants interfere with Parkin translocation to mitochondria. (d) Only co-expression of K27 or K63 ubiquitin recapitulates mitochondrial clearance similarly to 6×His-tagged wild-type ubiquitin after 24 h of CCCP treatment. Representative images are shown. Scale bars, 10 μm. Immunostaining of untreated cells and all other ubiquitin variant combinations tested are shown in Supplementary Information, Fig. S4a and b, c, respectively. WT, wild-type; PolyUb, poly-ubiquitin.
figf5(a, b) Stable Mito-DsRed (pseudo coloured; blue)-expressing HeLa cells were transfected with Flag-Parkin wild-type or pathogenic mutants. Cells were treated with CCCP for the indicated times before immunostaining with anti-Flag (green) and anti-p62 (red). (a) In contrast to the pathogenic mutants, wild-type Parkin colocalizes with p62 at the site of clustered mitochondria, after 6 h of CCCP treatment. (b) After 24 h of CCCP treatment, wild-type Parkin-transfected cells show complete loss of mitochondria, whereas K161N and R275W Parkin mutants colocalize with both p62 and mitochondria. In contrast, translocation-compromised mutants K211N, T240R and G430D, lacking the mitochondria-associated poly-ubiquitin signal (Fig. 4b), did not colocalize with p62. Representative images of four independent experiments are shown. Data from untreated control cells and quantification of colocalization of Parkin, mitochondria and p62 upon CCCP treatment are shown in Supplementary Information, Fig. 5a and b, c, respectively.(c, d) Control siRNA- or p62 siRNA-silenced HeLa cells were transfected with EGFP-Parkin wild-type. Cells were treated with CCCP for the indicated times and stained with anti-TOM20 (pseudo coloured; blue) to visualize mitochondrial morphology and anti-p62 (red) to monitor silencing efficiency. Parkin wild-type was visualized by EGFP epifluorescence (green). Parkin-positive cells with cleared mitochondria are surrounded by a line. ((c-f) Knockdown of p62 has no influence on Parkin translocation to mitochondria after 6 h of CCCP treatment (c-e), but completely blocks final clearance after 24 h (c, d, f). (e, f) Relative parkin translocation (e) and mitochondrial clearance (f) after p62 knockdown and CCCP treatment (n = 4). Data represent the mean ± s.d., ***P ≤ 0.0005 compared with control siRNA-transfected cells. Representative images of four independent experiments are shown. Scale bars, 10 μm. Immunostainings of control cells are shown in Supplementary Information, Fig. S5d, e.(g) Western blot of siRNA-transfected HeLa cells used in c-f demonstrates the efficiency of p62 silencing. β-Actin probing served as a loading control. WT, wild-type.
figf6(a) Time-course experiment of HeLa cells transfected with Flag-Parkin wild-type and treated with CCCP for the indicated periods. Total lysates were prepared, and western blots were probed with specific anti-Parkin, anti-PINK1, anti-TOM20 and anti-VDAC1 antibodies. β-Actin probing served as a loading control. All of the proteins detected are endogenously expressed, except Flag-Parkin.(b) Pathogenic Parkin mutants fail to poly-ubiquitylate endogenous VDAC1 in response to CCCP treatment. HeLa cells were transfected with empty vector (-), Flag-Parkin wild-type or pathogenic mutants along with 6×His-tagged ubiquitin wild-type for 24 h. Cells were treated with CCCP for 6 h and subsequently protein lysates were prepared in urea buffer. Denaturing conditions of Ni-NTA affinity purifications were used to specifically pulldown only proteins covalently modified with 6xHis-tagged ubiquitin. Western blots of protein lysates and purified Ni-NTA agarose elutions were probed with anti-VDAC1, anti-TOM20 and anti-Parkin antibodies. Modification of VDAC1 was observed in cells expressing Parkin wild-type and the functional mutant G328E, whereas non-functional mutants did not have this effect. ((c) In response to CCCP treatment, Parkin catalyses predominantly K27-linked poly-ubiquitin chains on endogenous VDAC1 and is itself strongly poly-ubiquitylated. HeLa cells were transfected with an empty vector (-) or Flag-Parkin wild-type along with 6×His-tagged ubiquitin variants for 24 h. Treatment of cells, preparation of lysates and Ni-NTA purification were performed as described in c and probed for Parkin, VDAC1 and β-actin. WT, wild-type; Ub, ubiquitin.
figf7(a) Western blot analysis of parental SH-SY5Y cells treated with CCCP for the indicated times. Time-course experiments of CCCP-treated neuronal cells reveal increasing modifications of VDAC1 over time. Total lysates were prepared, and western blots were probed with specific anti-Parkin, anti-PINK1, anti-TOM20 and anti-VDAC1 antibodies. All proteins represent endogenous levels.(b) Immunoprecipitations of Parkin and VDAC1 from parental SH-SY5Y cells confirm ubiquitylation of both proteins. CCCP treatment of neuronal cells increases ubiquitylated species of endogenous Parkin and VDAC1 over time. Using specific antibodies, Parkin and VDAC1 were immunoprecipitated from lysates of parental SH-SY5Y cells at different time points, western blotted and probed with anti-ubiquitin, anti-Parkin and anti-VDAC1 antibodies.(c) Pathogenic Parkin mutations fail to poly-ubiquitylate endogenous VDAC1 in response to CCCP treatment. Western blot analysis of a time-course experiment with inducible Parkin SH-SY5Y cells after CCCP treatment. Total lysates were prepared, and western blots were probed with specific anti-Parkin and anti-VDAC1 antibodies. β-Actin probing served as a loading control in a-c. WT, wild-type; Ub, ubiquitin.
figf8VDAC1-specific siRNA abrogates Parkin translocation to mitochondria after 2 h, and mitochondrial clearance after 24 h, of CCCP treatment. Both effects can be rescued by re-transfection with wild-type VDAC1. (a) Immunofluorescence and (b) western blot of siRNA-transfected HeLa cells used in c-g demonstrate partial silencing of endogenous VDAC1. (a) Silenced cells were stained with anti-HtrA2/Omi, a mitochondrial marker (pseudo coloured; blue), and anti-VDAC1 (red) antibodies. (b) Lysates from silenced cells were subjected to western blot analysis and probed with an anti-VDAC1 antibody, while TOM20 and β-actin probing served as loading controls.(c-e) Control siRNA- or VDAC1 siRNA-silenced HeLa cells were transfected with the indicated combinations of EGFP-Parkin wild-type, VDAC1-Flag wild-type or appropriate empty vector controls. Cells were treated with CCCP for 2 h and 24 h and stained with anti-HtrA2/Omi (pseudo coloured; blue) and anti-Flag (red) to visualize mitochondrial morphology and re-transfected VDAC1, respectively. Wild-type Parkin was visualized by EGFP epifluorescence (green). Parkin-positive cells are surrounded by a line. Representative pictures of three independent experiments are shown. Scale bars, 10 μm.(f, g) Quantification of d (f) and e (g). Parkin wild-type colocalization with impaired mitochondria after 2 h (f) and uncleared mitochondria after 24 h (g) of CCCP treatment (n = 3). Data represent the mean ± s.d., *P ≤ 0.05 compared with control siRNA-transfected or with VDAC1-Flag wild-type-transfected cells.