EMBO/SourceData huggingface dataset:
figf1(b) MAPPIT screen identified RAL-interacting proteins. A MAPPIT array covering close to 8,500 preys was screened with RALA-G23V as bait. Data are shown in a volcano plot of the log ratio of normalized MAPPIT luciferase activity versus P value Source data can be found in Supplementary Table S1.(c) MAPPIT assay confirmed interaction between the RAL proteins and USP33. RALA-G23V or RALB-G23V baits were introduced into HEK293T cells together with the indicated preys. The results are expressed as a mean of normalized luciferase activity ± s.d (leptin-treated cells versus leptin-untreated cells) for three independent experiments. Statistics source data can be found in Supplementary Table S1.(d,e) USP33 interacts with both RALA and RALB. At 48 h post-transfection with tagged USP33 and RAL expression constructs, the indicated proteins were then immunoprecipitated with anti-Flag (M2) or anti-HA-agarose, followed by immunoblotting using anti-Flag or anti-HA antibodies. WCL, whole-cell lysate; IP, immunoprecipitates.(f) Endogenous USP33 interacts with RALB. Flag-RALB was immunoprecipitated using anti-Flag (M2) agarose and analysed for co-precipitation with endogenous USP33 using anti-USP33 antibody. Cells expressing USP33 shRNA were used as a negative control.(g) GTP binding is not required for interaction between USP33 and the RAL proteins. The GST-tagged RALA and RALB were isolated with glutathione-agarose and mixed with lysates derived from HEK293T cells expressing Flag-USP33 in the presence of GTPγS or excess of GDP followed by immunoblotting with Flag-specific antibody.(h) USP33 affects ubiquitylation of RALB, but not RALA. 6xHis-tagged ubiquitin and Flag-RAL-G23V mutants were introduced into HEK293T cells stably expressing GFP shRNA or USP33 shRNA. Ubiquitylated RAL proteins were purified by Co2+ metal affinity chromatography and detected by antibodies specific to RALA or RALB. Uncropped images of blots are shown in Supplementary Fig. S7.(g) GTP binding is not required for interaction between USP33 and the RAL proteins. The USP33-tagged RALA and RALB were isolated with glutathione-agarose and mixed with lysates derived from HEK293T cells expressing Flag-USP33 in the presence of GTPγS or excess of GDP followed by immunoblotting with Flag-specific antibody.
figf2(a) Tandem affinity purification of ubiquitylated RALB. 6xHis-ubiquitin and Flag-RALB-G23V were co-transfected into HEK293T cells, and ubiquitylated RALB was purified using anti-Flag resin followed by Co2+ metal affinity chromatography. Isolated RALB was visualized by immunoblotting using anti-RALB antibody.(b) RALB undergoes ubiquitylation on multiple sites. Schematic diagram of the RALB domains (upper panel). RALB ubiquitylation sites were identified in two independent tandem mass spectrometry analyses with a total coverage of 63% of the RALB amino acid sequence (Supplementary Fig. S4a). The major identified ubiquitylation sites, Lys 47 and Lys 160, are located in the effector-interacting domain (green) and the G5 box (red), respectively.(c) Substitution of arginine for lysine at position 47 significantly inhibits ubiquitylation of RALB. ((d) USP33 regulates RALB ubiquitylation at Lys 47. (e) The GTP-GDP status of RALB affects RALB ubiquitylation at Lys 47. For c-e, 6xHis-tagged ubiquitin and the indicated RALB mutants were introduced into HEK293T cells expressing GFP shRNA or USP33 shRNA. Ubiquitylated RALB was purified by Co2+ metal affinity chromatography and detected by antibodies specific to RALB. WT, wild type.(f) Lack of ubiquitylation at Lys 47 inhibits RALB binding to SEC5. The indicated Flag-tagged RALB mutants were overexpressed in HEK293T cells and then immunoprecipitated with anti-Flag (M2) agarose followed by immunoblotting using anti-SEC5 antibody.g) Ubiquitylation at Lys 47 impairs RALB binding to EXO84. Flag-tagged RALB mutants were overexpressed in HEK293T cells and then immunoprecipitated with anti-Flag (M2) agarose followed by immunoblotting using anti-EXO84 antibody.(h) Ubiquitylation at Lys 47 does not affect RALB activity. The activity of RALB mutants was determined by a RALBP1-RBD binding assay.(i) The Rosetta v3 protocol described in ref. was used for ubiquitin-docking simulations. The plot represents the energies of the produced decoys distributed by the root-mean-square deviation (RMSD) of ubiquitin position relative to RALA from an arbitrarily chosen decoy.(j) Rosetta modelling of ubiquitylated-RALA-SEC5-RBD and ubiquitylated-RALA-EXO84-RBD complexes. Superposition of the top ten refined solutions of ubiquitylated-RALA-SEC5-RBD complex, selected by combined scores of two independent docking simulations of ubiquitylated-RALA-SEC5-RBD and ubiquitylated-RALA (left). Simulated ubiquitin positions linked to Lys 47 of RALA were combined with the RALA-EXO84 complex (right). Uncropped images of blots are shown in Supplementary Fig. S7.
figf3(a) USP33 does not affect RALB activity. The activity of RALB was determined in HEK293T cells expressing GFP shRNA or USP33 shRNA and empty vector (V) or HA-tagged USP33 by RALBP1-RBD binding assay.(b) USP33 modulates interaction between RALB and SEC5. Flag-tagged RALB was overexpressed in HEK293T cells expressing GFP shRNA, USP33 shRNA, empty vector (V) or HA-tagged USP33. The indicated proteins were then immunoprecipitated with anti-Flag (M2) agarose followed by immunoblotting using anti-Flag or anti-SEC5 antibodies.(c) USP33 regulates RALB binding to EXO84. Flag-tagged RALB was immunoprecipitated using anti-Flag (M2) agarose from HEK293T cells expressing the indicated constructs. The presence of EXO84 in RALB complexes was analysed by immunoblotting using anti-HA or anti-EXO84 antibody.(d) Activated RALB co-localizes with both EXO84 and SEC5. At 24 h after co-transfection with RALB-G23V-EGFP and HA-EXO84, HeLa cells were immunostained with anti-HA and anti-SEC5 antibodies. Scale bars, 10 μm. The outlined areas are shown at higher magnification in the bottom panels.(e) RALB ubiquitylation controls interaction between EXO84 and SEC5. Flag-tagged SEC5 was immunoprecipitated using anti-Flag (M2) agarose from HEK293T cells overexpressing RALB-G23V or RALB-G23V-K47R. The presence of EXO84 in SEC5 complexes was analysed by immunoblotting using anti-EXO84 antibody.(f) USP33 regulates EXO84-SEC5 complex formation. Flag-tagged SEC5 was immunoprecipitated using anti-Flag (M2) agarose from HEK293T cells expressing the indicated constructs followed by immunoblotting using anti-EXO84 antibody.(g) Suppression of SEC5 affects RALB binding to EXO84. HA-tagged RALB-G23V was immunoprecipitated from HEK293T cells expressing the indicated constructs. The presence of EXO84 in RALB complexes was analysed by immunoblotting using anti-EXO84 antibody. For a-c,f,g immunoblotting using antibodies specific for USP33, anti-Flag (M2) or anti-HA determined the levels of USP33 suppression or overexpression. Immunoblot analysis was performed using the indicated antibodies. Uncropped images of blots are shown in Supplementary Fig. S7.
figf4(a) Suppression of USP33 facilitates TBK1-SEC5 complex formation. Flag-tagged SEC5 was introduced into HEK293T cells expressing empty vector (V) or HA-tagged RALB-G23V together with GFP shRNA or USP33 shRNA as indicated, and then immunoprecipitated with anti-Flag (M2) agarose followed by immunoblotting using antibody specific for TBK1.(c) RALB ubiquitylation at Lys 47 is crucial for formation of the RALB-SEC5 complex in response to poly(I:C) treatment. Flag-tagged SEC5 and the indicated HA-tagged RALB mutants were introduced into 293-hTLR3 cells. At 48 h after transfection cells were treated 100 μg ml−1 of poly(I:C) for 6 h. Flag-tagged SEC5 was immunoprecipitated with anti-Flag (M2), and analysed for co-precipitation by immunoblotting using anti-HA antibody.(c) RALB ubiquitylation at Lys 47 is crucial for formation of the RALB-SEC5 complex in response to poly(I:C) treatment. Flag-tagged SEC5 and the indicated HA-tagged RALB mutants were introduced into 293-hTLR3 cells. At 48 h after transfection cells were treated 100 μg ml−1 of poly(I:C) for 6 h. Flag-tagged SEC5 was immunoprecipitated with anti-Flag (M2), and analysed for co-precipitation by immunoblotting using anti-HA antibody.(d) RALB ubiquitylation at Lys 47 affects activation of TBK1 and IRF3. At 48 h after transfection with empty vector (V), Flag-RALB-G23V and Flag-RALB-G23V-K47R, 293-hTLR3 cells were treated with 10 μg ml−1 of poly(I:C) for 6 h. Immunoblot analysis was performed using the indicated antibodies. Uncropped images of blots are shown in Supplementary Fig. S7.
figf5(a-d) USP33 inhibits assembly of SEC5-beclin-1 complexes. The indicated proteins were immunoprecipitated from cells expressing GFP shRNA or USP33 shRNA with anti-Flag (M2), anti-HA or anti-SEC5 antibody and analysed for co-precipitation by immunoblotting using specific antibodies as indicated.(e) USP33 potentiates the interaction between EXO84 and beclin 1. Endogenous beclin 1 was immunoprecipitated from HEK293T cells, expressing either empty vector (V), HA-USP33 wild type (WT) or the catalytically inactive mutant C194S-H683Q, using anti-beclin 1 antibody. Immunoprecipitates were analysed for co-precipitation by immunoblotting using anti-EXO84 or anti-beclin 1 antibodies.(f,g) RALB but not RALA undergoes deubiquitylation under nutrient deprivation. 6xHis-tagged ubiquitin and the indicated RAL mutants were overexpressed in HEK293T cells. At 48 h after transfection cells were deprived of nutrients and incubated in Hank's buffered salt solution (HBSS) medium for 90 min. Ubiquitylated RALproteins were purified by Co2+ metal affinity chromatography and analysed by immunoblotting using anti-RALA or anti-RALB antibodies.(h) Nutrient starvation results in the accumulation of USP33. HEK TE cells were incubated in HBSS medium for the indicated periods of time. Immunoblotting was performed using anti-USP33 antibody.(i) USP33 co-localizes with RALB-positive vesicles in the absence of nutrients. At 48 h after co-transfection with RALB-G23V-EGFP and USP33-mCherry, HeLa cells were incubated in HBSS medium for 90 min. Cells were imaged for EGFP and mCherry fluorescence. Scale bars, 10 μm. The outlined areas are shown at higher magnification in the bottom panels. Arrows indicate USP33 co-localization to RALB-positive vesicles.(j) Beclin 1 co-localizes with USP33. HeLa cells were transfected with beclin-1-HA and USP33-mCherry. At 48 h after transfection, cells were incubated in HBSS medium for 90 minutes and treated as in i. Scale bars, 10 μm. The outlined areas are shown at higher magnification in the bottom panels. Uncropped images of blots are shown in Supplementary Fig. S7.
figf6(a) USP33 depletion inhibits accumulation of LC3-lipid conjugates. HEK TE cells stably expressing GFP shRNA or USP33 shRNA were incubated with DMEM or HBSS medium for 4 h, in the presence or absence of 50 μM of chloroquine (CQ). Cells were then assayed for the relative accumulation of LC3-I and LC3-II by immunoblotting analysis using anti-LC3 antibody. LC3-II/GAPDH ratios have been calculated using ImageJ densitometric analysis.(b-d) USP33 expression levels affect the accumulation of LC3punctae. Wild-type USP33 or a USP33-shRNA-resistant USP33 mutant (USP33R) was introduced into HEK TE cells stably expressing GFP shRNA or USP33 shRNA. The generated cells were incubated in HBSS medium for 4 h. USP33 was analysed by immunoblotting using anti-USP33 antibody (b). Representative images of LC3immunostaining are shown (c). Endogenous LC3punctae were quantified using the In Cell Analyser 2000 automatic imaging system and IN Cell Investigator software. The mean distribution of LC3punctae per cell is represented as the mean of two independent experiments. Statistics source data for d can be found in Supplementary Table S1 (d).(e) USP33 depletion leads to increased levels of p62. HEK TE cells expressing GFP shRNA or USP33 shRNA were incubated in HBSS medium for the indicated periods of time. Immunoblotting was performed using the indicated antibodies.(f) Overexpression of the RALB-G23V-K47R mutant leads to accumulation of LC3-lipid conjugates. HEK293T cells overexpressing the RALB-G23V or RALB-G23V-K47R mutants were assayed for the relative accumulation of LC3-I and LC3-II by immunoblotting using anti-LC3 antibody.
Figure 1(A) Western Blot detection of ATM pS1981, SMCHD1, TRF2 and hnRNPA1 loading control in wild-type and two SMCHD1 knockout (KO1 and KO2) HeLa cells transfected with shTRF2 plasmid or EV control.(B) Representative metaphase spreads from wild-type and SMCHD1 knockout HeLa cells transfected with shTRF2 plasmid or EV control. Telomeric signals were detected with Cy3-OO-(CCCTAA)3 and are false colored in red, DNA is stained with DAPI and is false colored in cyan. Scale bar: 5µm.(C) Quantification of telomere fusions from experiment Bars represent average number of fused chromosome ends. SDs were obtained from 3 independent experiments (>3,000 telomeres counted/condition/experiment). (*) P < 0.05; unpaired two-tailed Student's t-test.(D) Representative cell cycle profiles from two biological replicates of WT and SMCHD1 KO HeLa cells transfected with shTRF2 plasmid or EV control. Cells were stained with propidium iodide and analyzed by Flow cytometry.
Figure 2(A) Western Blot detection of SMCHD1, TRF2 and hnRNPA1 in SMCHD1 wild-type or SMCHD1 knockout HeLa inducible shTRF2 cells treated with or without doxycycline for the indicated number of days (d7, d8, d11).(B) Quantification of telomere fusions in SMCHD1 wild-type or SMCHD1 knockout HeLa inducible shTRF2 cells treated with or without doxycycline for the indicated number of days (d7, d8, d11). Bars represent average number of fused chromosome ends. SDs were obtained from 3 independent experiments (>1,900 telomeres counted/condition/experiment). (***) P < 0.001, (**) P< 0.01; (*) P< 0.05; unpaired two-tailed Student's t-test.(C) Terminal Restriction Fragment (TRF) analysis of telomeric DNA to detect 3'overhang processing of genomic DNA isolated from SMCHD1 wild-type or SMCHD1 knockout HeLa inducible shTRF2 cells treated as in the experiment in (B). (Left) Radiolabeled (CCCTAA)n probe was hybridized with a short run (upper panel) and long run (lower panel) native DNA gel to detect the signal of the telomeric 3' overhang. Samples used for the short and the long run were from the same digestion split into two. Exo I treatment (+ Exo) was used as a control that single stranded telomeric signal was terminal. (Right) The total TTAGGG signal in the same lane was deteced upon denaturation and hybridization with the same probe.(D) Quantification of the telomeric overhang signal at d11 after doxycyclin addition to SMCHD1 wild-type and SMCHD1 knockout HeLa shTRF2 inducible cells. The bar graph represents the average overhang signal intensity from two biological replicates as percentage of the signal in the cells untreated with doxycycline with error bars representing the standard deviation (SD) of the sample.
Figure 3A Western blot detection of ATM pS1981, SMCHD, TRF2, γH2AX, and hnRNPA1 in WT or SMCHD1 KO Hela cells transfected with shTRF2 and EV control.B Representative images for CO-FISH on metaphase spreads in wild type (WT) Hela and U2OS cells. The leading strand telomeres were labeled by PNA-FISH with a (TTAGGG)3-Alexa488 probe (green), the lagging strand with a (CCCTAA)3-Cy5 probe (pink), and the DNA was stained with DAPI. Examples of telomere sister chromatid exchange (t-SCEs) events are marked with white arrows. Scale bar: 5µmC Quantification of chromosome ends with t-SCEs detected by CO-FISH. Data represent means of 2 independent experiments± SD (>700 telomeres/condition/experiment) with individual average values indicated.
Figure 4(A-C) Representative images for detection of ATM pS9181, γH2AX, and 53BP1 at telomeres in wild-type (WT) and SMCHD1 knockout HeLa cells transfected with shTRF2 plasmid and empty vector (EV) control. Immunofluoresence (IF) for ATM pS1981 (gray), γH2AX (green) and 53BP1 (yellow) was combined with telomeric (CCCTAA)3-FISH (red) and DAPI staining total DNA. Scale bars: 5µm(D) Quantification of the number of cells containing >5 Telomere dysfunction Induced Foci (TIFs) detected Data represent the mean of 4 independent experiments ± SD (>200 cells/condition/experiment) for ATM pS1981 and 3 independent experiments ± SD (>200 cells/condition/experiment) for γH2AX and 53BP1. (***) P < 0.001; unpaired two-tailed Student's t-test.(E) Quantification of the number of 53BP1 TIFs per cell detected from three independent experiments. Data represent individual values per cell with the bar representing mean ± SD. (***) P < 0.001; unpaired two-tailed Student's t-test.
Figure 5(A) Western blot detection of SMCHD1, ATMpS1981, CHK2 pT68, CHK1 pS345, RPA pS33, RPA pS4/8, γH2AX and Vinculin in wild-type or SMCHD1 KO HeLa cells γ-irradiated with 3Gy dose and harvested at the indicated times (1h, 12h, 24h) after the treatment.(B) Representative images for Immunofluoresence (IF) detection of ATMpS1981 in wild-type HeLa cells γ-irradiated with a dose of 3Gy and harvested after the indicated times. Scale bar: 5µm(C) Quantification of the average number of ATMpS1981 foci per cell detected as in (B) in wild-type and SMCHD1 KO γ-irradiated HeLa cells. Data represent mean of 3 independent experiments ± SD (>200 cells/condition/experiment) with individual average values indicated.
Figure 6(A) Western Blot detection of SMCHD1, TRF2, TPP1 and hnRNPA1 in wild-type or SMCHD1 knockout HeLa cells transfected with the indicated shRNAs (shTRF2, shTPP1, shTRF2/shTPP1) or EV control.(B) Representative metaphase spreads (Scale bar: 5µm) from HeLa cells transfected with indicated shRNAs or EV control and quantification of telomere fusions. Bars represent average number of fused chromosome ends. SDs were obtained from 3 independent experiments (>2,500 telomeres counted/condition/experiment). (***) P < 0.001; (**) P < 0.01 unpaired two-tailed Student's t-test.(C) Representative metaphase spreads (Scale bar: 5µm) from HeLa cells transfected with indicated shRNAs or EV control treated for 4 days with ATRi (VE-821) and quantification of telomere fusions. Bars represent average number of fused chromosome ends. SDs were obtained from 3 independent experiments (>2,000 telomeres counted/condition/experiment). (***) P < 0.001; (**) P < 0.01; (*) P < 0.05 unpaired two-tailed Student's t-test.
Figure 3The number of neoblasts did not change significantly following inhibition of the MTC-gene kiaa1429. Shown is FISH of smedwi-1 (A) in control and kiaa1429 (RNAi) animals (left). smedwi-1+ cells were counted following FISH and showed no significant difference in expression (right; bar represents average normalized cell count; Materials and Methods). Scale = 100 µm.The number of neoblasts did not change significantly following inhibition of the MTC-gene kiaa1429. Shown is FISH of h2b (B) in control and kiaa1429 (RNAi) animals (left). h2b+ cells were counted following FISH and showed no significant difference in expression (right; bar represents average normalized cell count; Materials and Methods). Scale = 100 µm.(E) Representative FACS plots of cells isolated from control (top) and kiaa1429 (RNAi) animals (bottom) show an increase in cell abundance in the X2 (Fincher et al, 2018) gate (green; Materials and Methods). (F) Quantification of the cells in each FACS gate in control and kiaa1429 (RNAi) animals showed a six-fold increase in the abundance of cells in the X2 gate (Student's t-test *** - p < 0.005. FACS experiments were performed in biological triplicates. Boxes represent the IQR, whiskers represent the 1.5 x IQR, and central band represents the med
figf1(b) Coimmuno-precipitation (IP) of Fbxo7-HA and Flag-Parkin in whole-cell lysates from U2OS cells over-expressing both proteins. IB, immunoblot. Molecular mass markers are in kilodaltons.(c) Coimmunoprecipitation of endogenous Fbxo7 with Flag-Parkin in HEK293T cells transfected with Flag-Parkin or a control protein (EGFP).(d) Flag immunoprecipitation was repeated in U2OS cells transfected with Flag-Parkin and either full-length (1-522) T7-Fbxo7 or an N-terminal truncation lacking the Ubl domain (89-522).(e) As in d, using lysates from U2OS cells expressing Flag-Parkin and T7-Fbxo7, either full length (1-522) or a C-terminal deletion of the proline-rich region (1-398). * indicates IgG heavy chain.(f) In vitro-translated Flag-Parkin was incubated with bacterially expressed GST or GST fused to the Fbxo7 Ubl domain (1-88) immobilized on glutathione beads. Bead-bound proteins and inputs were analyzed by immunoblotting with anti-Parkin antibodies.(g) The disease-causing mutation T22M interferes with Fbxo7's interaction with Parkin. Coimmunoprecipitation was performed as in b using lysates from U2OS cells expressing Flag-Parkin and WT or T22M Fbxo7-HA.(h) Coimmunoprecipitation of Flag-Parkin and Fbxo7 in the mitochondrial and cytosolic fractions of HEK293T cells overexpressing both proteins. CxVα and GAPDH are markers for mitochondria and cytoplasm, respectively. All western blots are representative of experiments performed at least three times. Full-length blots are presented in Supplementary Figure 9.
figf2(a) Fbxo7 relocates from the cytosolic to the mitochondrial fractions of HEK293T cells treated with CCCP (10 μM). IB, immunoblot.(b) Fbxo7 levels are increased in Flag-Parkin complexes immunoprecipitated (IP) from the mitochondrial fraction of HEK293T cells transfected with Flag-Parkin and untagged Fbxo7 following 1 or 3 h treatment with CCCP (10 µM).(c) Parkin localization at the mitochondria was assessed by immunocytochemistry in SH-SY5Y cells transfected with Flag-Parkin plus scrambled (scr) or Fbxo7 siRNA, following 1 or 3 h treatment with CCCP (10 μM). Cells were scored visually for the colocalization of Flag-Parkin with HtrA2, a mitochondrial marker. Images are displayed for cells transfected as indicated, following 0 or 3 h CCCP treatment. For corresponding images at 1 h treatment, see Supplementary Figure 2c. Nuclei (blue) were stained with DAPI. Scale bars, 10 μm.(d) Loss of Flag-Parkin translocation upon Fbxo7 silencing is rescued by WT and R378G Fbxo7, but not by T22M Fbxo7, by R498X Fbxo7 or by Fbxo7 in which the mitochondrial targeting sequence is mutated (mt-MTS). For c,d, histograms indicate the percentage of cells in which Parkin localized to the mitochondria. Data are presented as mean of three experiments ± s.e.m. *P 0.05, **P 0.01 compared to cells transfected with Flag-Parkin plus Fbxo7 siRNA.(e) T7-tagged WT Fbxo7 localizes to both cytosolic (C) and mitochondrial (M) fractions of transfected HEK293T cells, but MTS mutant (mt-MTS) Fbxo7 localizes only to the cytosolic fraction. CxVα and PDHE1α are mitochondrial markers; GAPDH is a cytosolic marker. All western blots are representative of experiments performed at least three times. Full-length blots are presented in Supplementary Figure 9.
figf3(a,b) Overexpression of Fbxo7 by da-GAL4 (da>Fbxo7) suppresses climbing (a) and flight (b) defects of parkin mutants.(c) Overexpression of Fbxo7 also suppresses dopaminergic (DA) neurodegeneration parkin mutants.(d-f) Top and middle panels, toluidine blue-stained sections of adult thorax. Bottom panels, transmission electron micrographs of muscle. Fbxo7 overexpression suppresses muscle degeneration and mitochondrial disruption in parkin mutants. Scale bars: 200 μm (top), 20 μm (middle), 2 μm (bottom). Images are representative of three animals per genotype.(g,h) Overexpression of Fbxo7 pathogenic mutants, mt-MTS or isoform 2 by da-GAL4 fails to rescue climbing (g) and flight (h) deficits in parkin mutants. Control genotype is park25/+; da-GAL4/+. All transgenic lines are site-directed integration except WT(4), which is random integration line 4 (see Supplementary Fig. 3 and Online Methods). Histograms indicate mean ± s.e.m. One-way ANOVA with Bonferroni correction (***P 0.001, **P 0.01). For climbing and flight assays, at least 50 flies were assessed; number of flies is shown for each bar.