EMBO/SourceData huggingface dataset:
Figure 7(A) siRNA-based knockdown of Pex3, Pex16, and Pex19. HeLa cell lysates treated with the indicated plasmids and siRNAs were immunoblotted with the indicated antibodies.(B) A comparable amount of MITOL was detected in control, PEX3-, PEX16-, and PEX19-knockdown cells. HeLa cell lysates stably expressing HA-Parkin and 3Flag-MITOL treated with the corresponding siRNAs were immunoblotted with the indicated antibodies.(C) MITOL translocation from the mitochondria to peroxisomes is highly dependent on Pex3. HeLa cells stably expressing 3Flag-MITOL and HA-Parkin were transfected with control, PEX3, PEX16, or PEX19 siRNA, treated with 15 µM CCCP for 3 hours, and then subjected to immunocytochemistry with anti-Flag and anti-catalase antibodies. Scale bars, 10 µm.(D) Correlation statistics for the localization of 3Flag-MITOL and catalase in cells transfected with the indicated siRNAs. Dots indicate individual Pearson correlation coefficient data points. In the box-plots, the center lines indicate the medians, the box limits indicate the 25th and 75th percentiles as determined in the R software package, and the whiskers extend 1.5 times the interquartile range from the 25th and 75th percentiles. Means and the number of samples are shown on the box and X-axis, respectively. Statistical significance was calculated using a one-tailed Welch's t-test.
Figure 8(A) MITOL did not merge with Hsp60 in control siRNA-treated cells, whereas most MITOL co-localized with Hsp60 in p97/VCP knockdown cells in response to mitophagy stimuli. HeLa cells stably expressing 3Flag-MITOL and HA-Parkin were transfected with control or p97/VCP siRNA, treated with 15 µM CCCP for 3 hours, and then subjected to immunocytochemistry with anti-Flag, anti-catalase, and anti-Hsp60 antibodies. Scale bars, 10 µm.(B) HeLa cell lysates treated with control or p97/VCP siRNA were immunoblotted with anti-p97/VCP and anti-tubulin antibodies.(C) Overexpression of an p97/VCP ATP hydrolysis-defective mutant, E305Q/E578Q (p97QQ), blocked MITOL redistribution from mitochondria to peroxisomes, while overexpression of wild-type p97/VCP had no effect on MITOL redistribution. HeLa cells stably expressing GFP-Parkin were transfected with MITOL-HA and Flag-p97/VCP wild-type or p97QQ, treated with 15 µM CCCP for 3 hours, and then subjected to immunocytochemistry with anti-HA and anti-catalase antibodies. Higher magnification images of the boxed regions are shown in the small panel. Scale bars, 10 µm. Arrowheads indicate representative examples of MITOL-peroxisome co-localization that was only observed in the presence of a functional VCP.(D) NMS-873, a specific inhibitor of p97/VCP, prevented MITOL translocation following CCCP-treatment. HeLa cells stably expressing HA-Parkin were transfected with 3Flag-MITOL, treated with 15 µM CCCP in the presence or absence of 10 µM NMS-873 for 3 hours, and then subjected to immuno-staining with anti-Flag, anti-catalase, and anti-HA antibodies. Higher magnification images of the boxed regions are shown in the small panel. Scale bars, 10 µm. Arrowheads indicate representative examples of MITOL-peroxisome co-localization that was only observed in the presence of a functional VCP.(E) Correlation statistics for the localization of 3Flag-MITOL and catalase in the presence of NMS-873. Dots indicate individual Pearson correlation coefficient data points. In the box-plots, the center lines indicate the medians, the box limits indicate the 25th and 75th percentiles as determined in the R software package, and the whiskers extend 1.5 times the interquartile range from the 25th and 75th percentiles. Means and the number of samples are shown on the box and X-axis, respectively. Statistical significance was calculated using a one-tailed Welch's t-test.
Figure 9(A) MITOL was ubiquitylated only in the presence of Parkin when the mitochondrial membrane was decreased. After 15 µM CCCP treatment for 3 hours, HeLa cells stably expressing HA-Parkin and 3Flag-MITOL were immunoprecipitated with anti-Flag magnetic beads, and then immunoblotted with the indicated antibodies. Red bars indicate ubiquitylation; the black arrowhead indicates 3Flag-MITOL.(B) The characteristic ubiquitylation ladder was observed for wild-type MITOL, but was absent in the K268A and K54A/K268A mutants. Black arrowhead indicates 3Flag-MITOL.(C) The MITOL K268A and K268R mutants were targeted to mitochondria under steady-state conditions, whereas peroxisomal localization following CCCP treatment was considerably disrupted. HeLa cells stably expressing HA-Parkin were transfected with 3Flag-MITOL wild-type, K268A, or K268R mutants, treated with 15 µM CCCP for 3 hours, and then subjected to immuno-staining with anti-Flag and anti-catalase antibodies. Scale bars, 10 µm.(D) The double K54/K268 mutation did not change the MITOL localization pattern. The subcellular localization of the MITOL K268A or K268R mutants was not drastically changed by inclusion of the K54A or K54R mutations. Scale bars, 10 µm.(E) Correlation statistics for the localization of 3Flag-MITOL wild-type, K268A, or K268R mutants with catalase. Dots indicate individual Pearson correlation coefficient data points. In the box-plots, the center lines indicate the medians, the box limits indicate the 25th and 75th percentiles as determined in the R software package, and the whiskers extend 1.5 times the interquartile range from the 25th and 75th percentiles. Means and the number of samples are shown on the box and X-axis, respectively. Statistical significance was calculated using a one-tailed Welch's t-test.(F) The fold change in ubiquitylation of MITOL K268, K40, and K54 in valinomycin-treated samples versus untreated samples. After 3 hours of valinomycin treatment, PEX19 -/- HCT116 cells stably expressing HA-Parkin and 3Flag-MITOL were immunoprecipitated with anti-Flag magnetic beads, and then subjected to LC-MS/MS analysis for label-free quantification of ubiquitylated peptides. Error bars represent the mean ± s.e.m in three biological replicates.
Figure 10(A) To generate MITOL-3Flag knock-in (KI) HCT116 cell lines, 3xFlag gene cassettes were inserted upstream of the MITOL stop codon using CRISPR/Cas9-based gene editing. Insertion of the 3Flag-tag was verified by immunoblotting with an anti-Flag antibody. Asterisk indicates a cross-reacting band.(B) The MITOL subcellular localization was observed in MITOL-3Flag KI HCT116 cells stably expressing HA-Parkin with anti-Flag, anti-catalase, and anti-Hsp60 antibodies. Endogenous MITOL (detectable with an anti-Flag antibody) overlapped with Hsp60 under steady-state conditions, whereas 3 hours of valinomycin (10 µM) treatment induced translocation of endogenous MITOL from mitochondria to peroxisomes. Higher magnification images of the boxed regions are shown in the bottom panel. Scale bars, 10 µm.(C) Correlation statistics for the localization of endogenous MITOL-3Flag with catalase. Dots indicate individual Pearson correlation coefficient data points. In the box-plots, the center lines show the medians, box limits indicate the 25th and 75th percentiles as determined by the R software package, and whiskers extend 1.5 times the interquartile range from the 25th and 75th percentiles. Means and the number of samples are shown on the box and the X-axis, respectively. Statistical significance was calculated using a one-tailed Welch's t-test.(D) The extraction of endogenous MITOL from depolarized mitochondria is blocked by the p97/VCP inhibitor NMS-873. Higher magnification images of the boxed regions are shown in the lower panel. Scale bars, 10 µm.(E) Correlation statistics for the localization of endogenous MITOL and PMP70 in the presence of NMS-873. Dots indicate individual Pearson correlation coefficient data points. In the box-plots, the center lines show the medians, box limits indicate the 25th and 75th percentiles as determined by the R software package, and whiskers extend 1.5 times the interquartile range from the 25th and 75th percentiles. Means and the number of samples are shown on the box and the X-axis, respectively. Statistical significance was calculated using a one-tailed Welch's t-test.(F) Endogenous MITOL is ubiquitylated following valinomycin treatment. After MITOL-3Flag KI HCT116 cells stably expressing HA-Parkin were treated with valinomycin for 3 hours, the collected cell lysates were immunoprecipitated with anti-Flag magnetic beads. The immunoprecipitates were blotted using anti-Flag and anti-ubiquitin antibodies. Red bars indicate ubiquitylation; the black arrowhead indicates MITOL-3Flag.
Figure 11(A) Distribution of exogenous 3Flag-MITOL in the mitochondria‐rich or peroxisome-rich fraction following cellular fractionation. HCT116 cells stably expressing HA-Parkin and 3Flag-MITOL were subjected to fractionation and detected using anti‐Tom20, anti‐PMP70, and anti‐Flag antibodies. Tom20 and PMP70 were used as mitochondrial and peroxisomal markers, respectively. The 3,000 g and 100,000 g pellets represent the mitochondria‐rich and peroxisomes-rich fractions.(B) The recovery ratio of 3Flag-MITOL between the mitochondria-enriched (3,000 g pellet) and peroxisome-enriched fraction (100,000 g pellet) following valinomycin treatment for the indicated times. The ratio of peroxisome-localized 3Flag-MITOL to mitochondria-localized 3Flag-MITOL increased with valinomycin treatment for 3 hours. Graphic data represent results of two biological replicates. In scatter plot, dots indicate individual data points. Black dots indicate the ratio of 3Flag-MITOL collected in the mitochondria-enriched fractions, and red dots are the ratio of 3Flag-MITOL collected in the peroxisome-enriched fractions. Mean values are also shown.Distribution of endogenous MITOL in the mitochondria‐rich or peroxisome-rich fraction following cellular fractionation. The distribution of endogenous MITOL was examined using MITOL-3Flag knock-in HCT116 cells. Treatment of cells with valinomycin for 3 hours reduced the amount of endogenous MITOL in the mitochondria-enriched fraction, but concomitantly increased endogenous MITOL in the peroxisomes-enriched fraction.Distribution of endogenous MITOL in the mitochondria‐rich or peroxisome-rich fraction following cellular fractionation. The distribution of endogenous MITOL was examined using MITOL-3Flag knock-in HCT116 cells. Graphic data represent results of two biological replicates. In scatter plot, dots indicate individual data points. Black dots indicate the ratio of MITOL-3Flag collected in mitochondria-enriched fractions, and red dots are the ratio of MITOL-3Flag collected in the peroxisome-enriched fractions. Mean values are also shown.
Figure 12(A) HeLa cells expressing HA-Parkin and wild type 3Flag-MITOL or 3Flag-MITOL lacking C-terminal 8 amino acids (∆C8) were treated with 15 µM CCCP for 3 hours, and then subjected to immunocytochemistry with anti-Flag and anti-PMP70 antibodies. Expanded peroxisomes were observed in MITOL∆C8-expressing cells. Higher magnification images of the boxed regions are shown in the small panel. Scale bars, 10 µm.(B) 3Flag-MITOL∆C8 with the E3-inactive Cys65Ser/Cys68Ser (CS) and H43W mutations were transfected into HeLa cells stably expressing HA-Parkin, treated with 15 µM CCCP, and then subjected to immunocytochemistry with anti-Flag and anti-PMP70 antibodies. After 3 hours of CCCP treatment, both the CS and H43W mutants localized on peroxisomes but expansion was not observed. Scale bars, 10 µm.(C) HeLa cells expressing HA-Parkin and MITOL wild-type or ∆C8 were treated with 15 µM CCCP for 3 hours, and the number of peroxisomes was counted as PMP70-positive dots per 100 μm2. In the box-plots, dots indicate individual data points, the center lines show the medians, box limits indicate the 25th and 75th percentiles as determined by the R software package, and whiskers extend 1.5 times the interquartile range from the 25th and 75th percentiles. Means and the number of samples are shown on the box and the X-axis, respectively. Statistical significance was calculated using a one-tailed Welch's t-test. The abundance of peroxisomes in cells expressing MITOL∆C8 was significantly decreased as compared with cells expressing wild-type MITOL.(D) MITOL∆C8 causes a drastic expansion of peroxisomes following CCCP treatment. HeLa cells expressing HA-Parkin and wild-type or ∆C8 MITOL were treated with 15 µM CCCP for 3 hours, and the approximate size of peroxisomes was determined as the number of pixels occupied by one peroxisome. The PMP70-positive pixels per 100 µm2 were divided by the number of peroxisomes in the same area. In the box-plots, dots indicate individual data points, the center lines show the medians, box limits indicate the 25th and 75th percentiles as determined by the R software package, and whiskers extend 1.5 times the interquartile range from the 25th and 75th percentiles. Means and the number of samples are shown on the box and the X-axis, respectively. Statistical significance was calculated using a one-tailed Welch's t-test.
Figure 13(A and B) HeLa cells expressing HA-Parkin and MITOL∆C8 (A) or MITOL∆C8 lacking E3 activity (B) were treated with 15 µM CCCP for 3 hours, and then subjected to immunocytochemistry with anti-Flag and anti-ubiquitin antibodies. Expanded peroxisomes were ubiquitylated upon E3 activity of MITOL. Higher magnification images of the boxed regions are shown in the small panel. Scale bars, 10 µm.
Figure 5(A) Representative 5-day-old seedlings of wild-type Arabidopsis thaliana Col-0 and TF mutants gata12 and wri3 grown in the dark. Scale bar, 1 mm.(B) Heat map indicates which TFs significantly affects hypocotyl length, root length and the composite trait of root to total length in dark-grown seedlings and whether the effects of TFs are dependent on condition. TFs are hierarchically clustered using Euclidean distance.(C) Heat map of the average relative effects of TF mutant alleles on hypocotyl length, root length and the ratio of root to total length reveal that TF lesions significantly perturbed TCA cycle-dependent growth. Mutant alleles are listed in rows and traits in columns. Cells of TF mutant alleles in heat map are colored if the AGI or AGI:TCA Metabolite linear model terms for each trait are statistically significant (P < 0.05, two-way ANOVA, 16-20 seedlings per genotype per condition across two experiments per genotype). Mutant alleles are hierarchically clustered using Euclidean distance.
Figure 6(A) Heat map indicates which TFs significantly affects rosette area, growth rate, shoot biomass, flowering time and seed yield and whether the effects of TFs are dependent on salt treatment. TFs are hierarchically clustered using Euclidean distance.(C) Rosette area of mutant allele of BPC4 from day 7 to day 21 post-germination. Linear model for two-way ANOVA considers AGI, salt treatment, day post-germination and their interactions. The AGI and AGI:Salt Condition terms are statistically signification (P < 0.001, P < 0.01, respectively). Heat map under line plot indicates which term in linear model is statistically significant (P < 0.05) using two-way ANOVA for each day from 9 biological replicates per condition. Solid lines, Col-0; dashed line, bpc4; circle, control condition; triangle, 50 mM NaCl.
Figure 2(A) Hybridization Chain Reaction (HCR) detection of CGG repeat RNA along with immunocytochemistry (ICC) to detect SRSF1-FLAG in U2OS cells. Expanded view of merged channels shows the CGG RNA foci (arrowhead) and an example of SRSF1-CGG RNA foci co-localization (arrow). DAPI marks the nucleus. Scale bars are 10 µm.(B) Co-localization analysis of CGG RNA (red traces) and SRSF1 (green traces) showing overlaps of CGG RNA and SRSF1. (a.u. = arbitrary unit)(C) Co-immunoprecipitation of indicated SRSF proteins with PP7-tagged control sequence (partial nLUC sequence) to correct for non-specific binding, AUG and CGG reporter RNAs. SRSF1 and 2 specifically immunoprecipitated with PP7-tagged CGG reporter.
Figure 3(D) Representative photographs of fly eyes and quantitation (below) of rough eye scores with fly SRSF1 overexpression (dSF2 OE); n=20-32/genotype. Error bars represent mean +/- SD. Data information: For eye scoring, target siRNA lines were compared to non-targeting control siRNA lines using a two-tailed student's t test with Welch's correction for multiple comparisons. ∗∗p < 0.01; ∗∗∗p < 0.001; ∗∗∗∗p < 0.0001. Human orthologs of fly genes are used for labeling.(F) Quantitation of (GGGGCC)28-EGFP rough eye phenotype with SRSF modifiers (n > 30 flies/ genotype). Error bars represent mean +/- SD. Data information: For eye scoring, target siRNA lines were compared to non-targeting control siRNA lines using a two-tailed student's t test with Welch's correction for multiple comparisons. ∗∗p < 0.01; ∗∗∗p < 0.001; ∗∗∗∗p < 0.0001. Human orthologs of fly genes are used for labeling.(G) Representative photographs of fly eyes expressing GMR-GAL4 driven (GGGGCC)28-EGFP at 29˚C along with the quantifications of necrosis and eye width. n=28-30/genotype. Error bars represent mean +/- SD.(H-I) Survival assays of flies expressing (CGG)90-EGFP under Tub5-GS (H) and ELAV-GS (I) drivers with control or SRSF1 siRNAs. Expression of (CGG)90-EGFP was initiated with addition of drug starting 1 day post eclosion and continued through experiment (Log-rank Mantel-Cox test; n=98-101/genotype for Tub-GS and n=120-141/genotype for ELAV-GS flies) ∗p < 0.05, ∗∗p < 0.01. (J) Survival assays of (GGGGCC)28-EGFP expressing fly under Tub5-GS driver (Log-rank Mantel-Cox test; n=71-93/genotype) with control or SRSF1 siRNAs. ∗∗p < 0.01.
Figure 4(A, B) Representative (A) photographs of fly eyes and (B) quantitation with siRNA mediated knockdown of SRPK1 (dSRPK1); n=30-34/genotype. Error bars represent mean +/- SD. Data information: Statistical analysis was performed using two-tailed Student's t test with Welch's correction, ∗∗∗p < 0.001; ∗∗∗∗p < 0.0001.(C) Representative photographs of fly eyes expressing GMR-GAL4 driven (GGGGCC)28-EGFP with siRNA mediated knockdown of SRPK1 or disruption by insertion. (D) Quantitation of rough eye phenotypes. t-test with Welch corrections for comparisons with the control; n= 31-34 flies/ genotype. Error bars represent mean +/- SD. Data information: Statistical analysis was performed using two-tailed Student's t test with Welch's correction, ∗∗∗p < 0.001; ∗∗∗∗p < 0.0001.(E) Representative external eye imaging for detection of GFP aggregates caused by (CGG)90-EGFP transgene expression (top). Converted images used to quantify total intensity of GFP puncta (bottom). (F) Depletion of SRSF1 or SRPK1 by RNAi results in reduced (CGG)90-EGFP puncta compared to control siRNA as quantified by total intensity (a.u. = arbitrary unit). n=13-15 flies/genotype. Error bars represent mean +/- SD. Data information: Statistical analysis was performed using two-tailed Student's t test with Welch's correction, ∗∗∗p < 0.001; ∗∗∗∗p < 0.0001.
Figure 5(B) Anti-FLAG immunoblot of DMSO and SRPIN340 pre-treated HEK293T cells expressing AUG-nLuc-3xFLAG control or CGG-nLuc-3xFLAG RAN translation reporters. β-Actin is used as a loading control. To prevent signal saturation, AUG-nLuc lysate was diluted 1:3 in sample buffer prior to loading (n=3 biological replicates). Schematics of the AUG-nLUC-3xFLAG and +1CGG(100)-nLuc-3xFLAG reporters presented on top. Data information: Error bars represent mean +/- SD. Statistical analysis was performed using two-tailed Student's t test with Welch's correction. ∗p < 0.05; ∗∗p < 0.01, ∗∗∗p < 0.001 and ∗∗∗∗p < 0.0001. To prevent over-exposure, the AUG-nLuc lysate was diluted 1:3 in sample buffer.(D) Anti-FLAG immunoblot of DMSO and SRPIN340 pre-treated HEK293T cells expressing GGGGCC-nLuc-3xFLAG (GA70) and +2CGG-nLuc-3xFLAG (FMRpolyA) RAN translation reporters (n=3 biological replicates). Schematics of the GA70 (GGGGCCx70) and +2CGG reporters presented on top. Data information: Error bars represent mean +/- SD. Statistical analysis was performed using two-tailed Student's t test with Welch's correction. ∗p < 0.05; ∗∗p < 0.01, ∗∗∗p < 0.001 and ∗∗∗∗p < 0.0001.(E) Immunoblot of DMSO and SPHINX31 pre-treated HEK293T cells expressing AUG-nLuc-3xFLAG control or CGG-nLuc-3xFLAG RAN translation reporters. (n=3 biological replicates). (F) Anti-FLAG of DMSO and SPHINX31 pre-treated HEK293T cells expressing GGGGCC-nLuc-3xFLAG (GA70) and +2CGG-nLuc-3xFLAG (FMRpolyA) RAN translation reporters (n=3 biological replicates). Data information: Error bars represent mean +/- SD. Statistical analysis was performed using two-tailed Student's t test with Welch's correction. ∗p < 0.05; ∗∗p < 0.01, ∗∗∗p < 0.001 and ∗∗∗∗p < 0.0001.
Figure 6(C, D) Expression of GGGGCC-nLuc-3xFLAG (C) and +2CGG-nLuc-3xFLAG (D) RAN translation reporters in HEK293T cells treated with 2 μM TG (for stress induction) analyzed by immunoblot (n=3 biological replicates). To evaluate effects of SRPK1 inhibition cells were pre-treated with DMSO or SRPIN340 before reporter transfection. Data information: Error bars represent mean +/- SD. Two-tailed Student's t test with Welch's correction. ∗p < 0.05; ∗∗p < 0.01; ∗∗∗p < 0.001 and ∗∗∗∗p < 0.0001.(E) SRPK1 inhibition by SRPIN340 did not alter eIF2α phosphorylation in response to 2 μM TG (for stress induction) in HEK293T cells by immunoblot (n=3 biological replicates). (F) SPRK1 inhibition suppressed eIF2α phosphorylation in HEK293T cells treated with 2 μM TG (for stress induction) in the presence of the +1CGG reporter. Cells were pre-treated with DMSO or SRPIN340 before reporter transfection (n=3 biological replicates). Data information: Error bars represent mean +/- SD. Two-tailed Student's t test with Welch's correction. ∗p < 0.05; ∗∗p < 0.01; ∗∗∗p < 0.001 and ∗∗∗∗p < 0.0001.
Figure 7(B) ICC images of FLAG-tagged SRSF1 after SRPIN340 treatment compared to vehicle (DMSO). Quantification shows the ratio of nuclear and cytoplasmic intensity of SRSF1 signal Error bars indicate mean +/- 95% CI (n= 85-126 cells/condition). Statistical analysis was performed using t test with Welch's correction, ∗∗∗∗p < 0.0001.(C) Nucleocytoplasmic distribution CGG repeat RNA after SRPIN340 treatment compared to vehicle (DMSO) as detected by HCR. Quantification shows the ratio of nuclear and cytoplasmic intensity of CGG RNA signal as parts of whole. Error bars indicate mean +/- 95% CI (n= 124-151 cells/condition). Statistical analysis was performed using t test with Welch's correction, ∗∗∗∗p < 0.0001.(D) Anti-FLAG immunoblot blot of DMSO and SRPIN340 pre-treated HEK293T cells transfected with in vitro transcribed CGG-nLuc-3xFLAG reporter RNA. β-Actin is used as a loading control. Error bars represent mean +/- SD (n=6 biological replicates). Statistical analysis was performed using Student's t test with Welch's correction. ∗p < 0.05
Figure 8(A, B) Pharmacological targeting of SPRK1 with (A) 40 μM SRPIN340 or (B) 8 μM SPHINX31 reduced the cumulative risk of death in +1(CGG)100-EGFP (encoding FMRpolyG) expressing neurons. n= # of neurons quantified for each condition; Cox proportional hazard analysis, ∗∗∗p < 0.001.
Figure 1C Quantitative analysis of lysosomal movement from kymographs. Results were expressed as percent of total lysosomes (N = 44, 49, and 16 neurons for shSc, shLAMTOR1, and shLAMTOR+rLAMTOR1 respectively from 3-10 independent experiments). Data information: Data with error bars are represented as means ± SEM. Statistical significance was assessed by two-way ANOVA with Tukey's *P < 0.05, **P < 0.01, ***P < 0.001, as compared to shSc; #P < 0.05, ###P < 0.001, as compared to shLAMTOR1 n.s., not significant.G FRAP analysis of dendritic lysosome movement. Quantitative analysis for F (N = 7, 7, and 9 neurons for shSc, shLAMTOR1, and shLAMTOR+rLAMTOR1, respectively, from 3 independent experiments). Data information: Data with error bars are represented as means ± SEM. Statistical significance was assessed by Dunnett's post-test *P < 0.05, **P < 0.01, ***P < 0.001, as compared to shSc; #P < 0.05, ###P < 0.001, as compared to shLAMTOR1 ; n.s., not significant.