EMBO/SourceData huggingface dataset:
Figure 1(A) Homer1c-GFP signal (magenta) and immunostaining for surface AMPARs (cyan) and SP (green) in neurons treated for 48h with TTX, or untreated (UT). Scale bars: 10 µm (low magnification), 5 µm (insets). Dotted lines indicate the outline of dendrites. Arrowheads indicate SP+ synapses. (B) Percentage of SP+ synapses for untreated (UT) and TTX-treated neurons (dot plots represent different cells; UT: n = 26; TTX: n = 33, n indicates the number of cells, from 2 cultures). % SP+ spines: **P = 0.019 (Mann Whitney test). Data information: Data are represented as mean ± SEM.(C) AMPAR synaptic fluorescence intensity for SP+ versus SP- synapses in UT and TTX-treated neurons. AMPAR synaptic fluorescence intensity was normalized to SP- or small synapses, respectively, from UT condition. (UT: SP-, n = 1455, SP +, n = 516; TTX: SP-, n = 1529, SP+, n = 724, n indicates the number of synapses, from 2 cultures). **P < 0.01, ****P < 0.0001, ns, not significant, P > 0.05 (Kruskal-Wallis test followed by Dunn's multiple comparison test). Data information: Data are represented as mean ± SEM.
Figure 2(A) Example images of a FRAP experiment: SP- and SP+ spines from the same cultured hippocampal neuron transfected with SEP-GluA2 (gray and color-coded) + RFP-SP (red) 10s before, and 0, 370, 750 s after the photobleaching. Scale bars: 1 µm. Dotted lines represent the outline of dendrites. Arrowheads indicate dendritic spines which were targeted for photobleaching. (B) SEP-GluA2 fluorescence intensity at SP- vs SP+ spines. Each pair of dot plots represents average fluorescence for SP- and SP+ spines from a same neuron (4 cultures). **P = 0.0061 (two-tailed paired Student's t test). (C) Quantification of FRAP dynamics for SP- vs SP+ spines. Recovery curves represent SEP-GluA2 fluorescence average per cell (n = 14 cells, from 4 cultures). The two traces were fitted using double exponential components equations and the convergence of the traces to a common fit was tested using the extra sum of squares F test. The F test indicates that the traces are best fitted by two divergent models (P < 0.0001). (D) Quantification of the recovery fraction 750 s after the photobleaching. Each pair of dot plots represents average recovery for SP- and SP+ spines from a same neuron (4 cultures). **P = 0.0067 (Wilcoxon matched-pairs signed rank test). Data information: Data are represented as mean ± SEM.
Figure 3(A) Immunoblot analysis of SP in lysates from COS-7 cells which were untransfected, transfected with RFP-SP + empty vector or co-transfected with SP-shRNA-GFP + RFP-SP (knock-down) or shRNA-resistant RFP-SP (rescue). β-actin and GFP signals illustrate equal protein loading and SP-shRNA expression level, respectively. (B) Quantification of SP expression from 6 different experiments, normalized to the β-actin signal. *P < 0.05, ns, not significant, P > 0.05 (Kruskal-Wallis test followed by Dunn's multiple comparison test). Data information: Data represent mean ± SEM.(C) Homer-DsRed (green) and immunostained endogenous SP (red) in dendrites from neurons transfected with either empty vector, scramble shRNA or SP-shRNA with GFP reporter (blue). Scale bar: 10 µm. (D) Average SP intensity for same conditions (EV: n = 47; Scr-shRNA: n = 53; SP-shRNA: n = 62, n indicates the number of cells, from 3 cultures; normalized to empty vector condition). **P < 0.01, ****P < 0.0001 (Kruskal-Wallis test followed by Dunn's multiple comparison test). (E) Fraction of SP+ synapses for same conditions. (EV: n = 47; Scr-shRNA: n = 53; SP-shRNA: n = 62, n indicates the number of cells from 3 cultures). *P < 0.05 (Kruskal-Wallis test followed by Dunn's multiple comparison test). Data information: Data represent mean ± SEM.(F) Homer1c-DsRed (red) and immunostained surface AMPARs (green) in dendrites from neurons transfected with either SP-shRNA-GFP or empty vector (EV) with GFP reporter (blue) and treated with TTX or left untreated (UT). Scale bar: 5 µm. (G) AMPAR synaptic fluorescence intensity normalized to untreated empty vector (EV) condition (EV: UT, n = 42, TTX, n = 33; SP-shRNA: UT, n = 30, TTX, n = 31, n indicates the number of cells, from 3 cultures). *P < 0.05, **P < 0.01, ns, not significant, P > 0.05 (Kruskal-Wallis test followed by Dunn's multiple comparison test). Data information: Data represent mean ± SEM.
Figure 5(A) Micrographs showing Homer1c-GFP (green) and immunostaining for surface AMPARs (blue) and endogenous SP (red) in neurons transfected with miR-124 or control miR-67 (miR-Ctrl), and treated with TTX, or left untreated (UT). Scale bar: 5 µ (B) Percentage of SP+ synapses for same conditions as in (A) (miR-Ctrl: UT, n = 25, TTX, n = 26; miR-124: UT, n = 30, TTX, n = 30, n indicates the number of cells, from 3 cultures). ****P < 0.0001, ns, not significant, P > 0.05 (two-way ANOVA test followed by Tukey's multiple comparison test). (C) Homer1c-GFP intensity for same condition as in (A), normalized to untreated miR-Ctrl (miR-Ctrl: UT, n = 25, TTX, n = 26; miR-124: UT, n = 30, TTX, n = 30, n indicates the number of cells, from 3 cultures). ns, not significant, P > 0.05 (two-way ANOVA test followed by Tukey's multiple comparison test). (D) AMPAR synaptic fluorescence intensity for same condition as in (A), normalized to untreated miR-Ctrl (miR-Ctrl: UT, n = 25, TTX, n = 26, miR-124: UT, n = 30, TTX, n = 30, n indicates the number of cells, from 3 cultures). ***P < 0.001, *P < 0.01, ns, not significant, P > 0.05 (two-way ANOVA test followed by Tukey's multiple comparison test). Data information: Data are represented as mean ± SEM.
Figure 6(A) Micrographs showing dendrites from neurons transfected with Homer1c-DsRed (magenta) and SEP-GluA2 constructs containing wild-type (WT) or mutated (MUT) 3'UTR (green) and treated with TTX for 48 h, or left untreated (UT). Scale bar: 10 µm. (B) SEP-GluA2 synaptic fluorescence intensity for each condition, normalized to GluA2-3'UTR-WT untreated neurons (3'UTR-WT: UT, n = 29, TTX, n = 37; 3'UTR-MUT: UT, n = 18, TTX, n = 14; n indicates the number of cells, from 3 cultures). *P < 0.05, ns, not significant, P > 0.05 (Kruskal-Wallis test followed by Dunn's multiple comparison test). Data information: Data are represented as mean ± SEM.(C) Micrographs showing dendrites from neurons transfected with Homer1c-BFP (magenta), GFP-SP-shRNA (gray) and a rescue RFP-SP construct containing wild-type (WT) or mutated (MUT) 3'UTR (geen) and treated with TTX, or left untreated (UT). Scale bar: 10 µm. (D) Percentage of SP+ synapses for each condition (3'UTR-WT: UT, n = 26, TTX, n = 28; 3'UTR-MUT: UT, n = 26, TTX, n = 24; n indicates the number of cells, from 3 cultures). **P < 0.01, ***P < 0.001, ns, not significant, P > 0.05 (two-way ANOVA test followed by Tukey's multiple comparison test). Data information: Data are represented as mean ± SEM.(E) Micrographs showing Homer1c-GFP (magenta) and immunostaining for surface AMPARs (cyan) and endogenous SP (green) in neurons transfected with or without 50 nM SP TSB-LNA and treated with TTX, or left untreated (UT). Scale bar: 10 µm. (F) Percentage of SP+ synapses for each condition (Control: UT, n = 36, TTX, n = 52; SP TSB-LNA: UT, n = 62, TTX, n = 29; n indicates the number of cells from 3 cultures). *P < 0.05, **P < 0.01, ns, not significant, P > 0.05 (Kruskal-Wallis test followed by Dunn's multiple comparison test). (G) AMPAR synaptic fluorescence intensity for each condition, normalized to control untreated neurons (Control: UT, n = 30, TTX, n = 36; SP TSB-LNA: UT, n = 37, TTX, n = 20; n indicates the number of cells from 2 cultures). *P < 0.05, ns, not significant, P > 0.05 (Kruskal-Wallis test followed by Dunn's multiple comparison test). Data information: Data are represented as mean ± SEM.
Figure 7(A) Micrographs showing puro-PLA staining of newly synthesized SP (green) in neurons immunostained for MAP-2 (magenta) and DAPI (blue) and treated with TTX for 24 h or left untreated. The images on bottom panels show no staining in the absence of puromycin treatment or when omitting SP primary antibody. Scale bars: 30 µm (large view), 5 µm (insets).(C) Density of SP puro-PLA puncta, normalized to the untreated condition (UT) (UT: n = 62; TTX: n = 57, n represents the number of cells, from 3 cultures). *P < 0.05 (Mann-Whitney test). (D) SP puro-PLA cluster fluorescence intensity normalized to the untreated condition (UT) (UT: n = 62; TTX: n = 57, n indicates the number of cells, from 3 cultures). ****P < 0.0001 (Mann-Whitney test). Data information: Data are represented as mean ± SEM.(E) Micrographs showing puro-PLA staining of newly synthesized SP (green) in neurons transfected with Homer1c-GFP (magenta) and treated with TTX for 24 h or left untreated. Scale bar: 5 µm. Arrowheads indicate puro-PLA+ spines. (F) Percentage of SP puro-PLA+ synapses (UT, n = 26, TTX, n = 33; n indicates the number of cells, from 2 cultures). **P < 0.01, ns, not significant (Mann-Whitney test). (G) Homer1c-GFP integrated fluorescence intensity at SP puro-PLA- vs SP puro-PLA+ synapses (n = 32 cells, from 2 cultures). ****P < 0.0001, ns, not significant (Wilcoxon matched-pairs signed rank test). Data information: Data are represented as mean ± SEM.
Figure 8(A) Confocal images showing dendrites from CA3 pyramidal cells transfected with RFP-SP (green) containing wild-type (WT) or mutated (MUT) 3'UTR + SP-shRNA-BFP (magenta). Arrowheads indicate SP+ spines. Scale bar: 10 µm. (B) Graph plot showing spine head volume vs SP integrated intensity (n = 5 cells). Each plot represents a single spine for which SP integrated intensity has been normalized to average SP intensity of SP+ spines in the same neuron. Plots for SP- and SP+ spines appear in grey and magenta, respectively. The black dotted line represents linear regression (R2 = 0.25, P = 0.0004). (C) Paired data showing spine head volume for SP- vs SP+ spines. Each pair of plot represents average values for SP- vs SP+ spines for a given neuron. *P = 0.0031 (two-tailed Student t test). Data information: Data are represented as mean ± SEM.
Figure 9(F) Higher magnification of dendritic spines from neurons transfected with rescue RFP-SP (magenta) containing wild-type (WT) or mutated (MUT) 3'UTR and BFP-shRNA-SP (grey) and contacted by GFP-Syp+ terminals (green). Arrowheads indicate putative synaptic contacts. Scale bar: 5 μm. (G) Percentage of SP+ spines in neurons expressing RFP-SP-3'UTR-WT vs -MUT and depending on the apposition or not to a GFP-Syp+ terminal (SP-3'UTR-WT: TetTx-, n = 220, TetTx+, n = 26; SP-3'UTR-MUT: TetTx-, n = 616, TetTx+, n = 25; n indicates the number of spines from 5-7 pairs). (H) Spine head volume in same conditions as in (G) (SP-3'UTR-WT: TetTx-, n = 26, TetTx+, n = 26 spines from 5 pairs, 4 slices; SP-3'UTR-MUT: TetTx-, n = 25, TetTx+, n = 25; n indicates the number of spines from 7 pairs, 7 slices). ***P < 0.001, *P < 0.05, ns, not significant (Kruskall-Wallis test followed by Dunn's multiple test). (I) Cumulative probability distributions of spine head volumes for TetTx- and TetTx+ spines from neurons expressing RFP-SP-3'UTR-WT (SP-WT, light gray and light green) or RFP-SP-3'UTR-MUT (SP-MUT, dark gray and dark green). Data information: Data are represented as mean ± SEM.
Figure 1(c) Intravascular endothelial cell interactions and transmigration of neutrophils (Ly-6G+ CX3CR-1-; red) and cMOs (Ly-6G- CX3CR-1low; green) to the perivascular tissue as assessed 6 h after intrascrotal stimulation with recombinant murine uPA, PAI-1, or uPA-PAI-1 in postcapillary venules of the cremaster of CX3CR-1GFP/+ mice by multi-channel in vivo microscopy. Representative still images (scale bar: 50: µm) and quantitative data are shown (mean±SEM for n=4 mice per group; #p<0.05 vs. saline; *p<0.05 vs. uPA; §p<0.05 vs. PAI-1; One-way ANOVA).
Figure 2(b) Expression of PECAM-1/CD31 (red) and ICAM-1/CD54 or VCAM-1/CD106 (green) in the cremaster muscle of WT mice as assessed ex vivo by confocal laser scanning microscopy 6 h after intrascrotal injection of recombinant murine uPA-PAI-1 or saline, representative images (scale bar: 50 µm) and quantitative data are shown (mean±SEM for n=4 mice per group; #p<0.05 vs. saline; t test).(g) Quantitative analysis of LFA-1/CD11a clustering on the surface of mouse neutrophils under increasing flow conditions in vitro in the presence of either E-selectin/CD62E + ICAM-1/CD54, E-selectin/CD62E + ICAM-1/CD54 + KC, or E-selectin/CD62E + ICAM-1/CD54 + KC + uPA-PAI-1 as assessed by spinning disk confocal microscopy, representative images and quantitative data are shown (scale bar: 10 μm; mean±SD; n=3 mice; n=10-13 flow chambers, n =122-222 cells); *p<0.05 vs. E-selectin/CD62E + ICAM-1/CD54; One-way ANOVA).
Figure 3(b) Correlation analyses of RNA expression levels of uPA (PLAU gene), PAI-1 (SERPINE1 gene), and the neutrophil marker gene FPR1, and overall survival of breast cancer patients (stages 0 and 1) with high and low PLAU or SERPINE1 gene expression levels (cut-off z≥ 2.0) in the METABRIC breast cancer cohort.(c) Surface expression of MMP-9, VEGF, and NE as assessed on circulating neutrophils isolated from the peripheral blood of WT mice (saline) or from the peritoneal cavity of WT mice 6 h after intraperitoneal stimulation with uPA-PAI-1 (uPA-PAI-1) by multi-channel flow cytometry, quantitative data are shown (mean±SEM for n=4-6 mice per group; #p<0.05 vs. saline; t test).(f) Formation of NETs (histone H3+; green) as assessed ex vivo by confocal microscopy in the cremaster muscle of WT mice 6 h after intra-scrotal injection of uPA-PAI-1, TNF, or saline, PECAM-1/CD31+ postcapillary venules (blue) and Ly-6G+ neutrophils (red) are depicted. Representative images are shown (scale bar: 50 µm).
Figure 4(a) Effect of compound WX-340 on binding of recombinant murine uPA to PAI-1 protein as assessed by ELISA, quantitative data are shown (mean±SEM for n=3 experiments per group; #p<0.05 vs. drug vehicle; One-way ANOVA).(d) Relative development rates and tumor weight in animals treated with WX-340 a priori or therapeutically after 1 week after tumor cell injection on a daily basis as assessed in an orthotopic model of 4T1 breast cancer in WT mice (mean±SEM for n=4-6 mice per group; *p<0.05 vs. drug vehicle; One-way ANOVA).(f) Numbers of neutrophils and 4T1 tumor cells in lungs and brain of WT mice receiving WX-340 or vehicle therapeutically after 1 week after tumor cell injection on a daily basis as assessed 14 days after intravenous injection of 4T1 tumor cells by multi-channel flow cytometry, quantitative data are shown (mean±SEM for n=4-6 mice per group; *p<0.05 vs. drug vehicle; t test).
Figure 1C Immunofluorescent analyses of USP33 (red), the hypoxia marker CA9 (green), and the stem cell marker SOX2 (gray) in human primary GBMs. Arrows indicate the USP33+/CA9+/SOX2+ cells. Scale bar, 80 µm.E Immunofluorescent analyses of USP33 (red) and the hypoxic cell population labeled by pimonidazole (green) in intracranial xenografts derived from T3359 GSCs. Mice bearing intracranial xenografts were injected intravenously (tail vein) with 60 mg/kg of pimonidazole and were sacrificed 2 hours post injection. Hypoxic cells were labeled with the FITC-conjugated mouse monoclonal anti-pimonidazole antibody. Scale bar, 80 µm.G Immunoblot analysis of USP33, HIF2α and HIF1α protein levels in GSCs, NSTCs and NPCs in normoxic and hypoxic conditions. Hypoxia (5% O2) relative to normoxia (20% O2) clearly induced USP33 and HIF2α expression in GSCs but not NSTCs or NPCs. The mild hypoxia of 5% O2 showed negligible induction of HIF1α in all cells.
Figure 2A, Representative images of immunofluorescent analyses of USP33 (red) and HIF2α (green) in human primary GBMs. Frozen sections of human GBMs were immunostained with antibodies against USP33 and HIF2α, and counterstained with DAPI to show nuclei (blue). Scale bar, 40 μm. (n = 5 sections; mean ± s.e.m.).F Immunoblot analysis of ectopic HIF2α protein levels in 293T cells with gradually increased amount of ectopic USP33. 0.5 µg of HA-tagged HIF2α plasmids together with the increased amounts of GFP-tagged USP33 plasmids (0, 0.1, 0.2 or 0.3 μg) were introduced into 293T cells. Forty-eight hours post transfection, levels of ectopic HIF2α-HA and GFP-USP33 were analyzed by immunoblot analysis. Concomitantly increased levels of ectopic HIF2α and USP33 expression indicated the positive regulation of HIF2α protein by USP33. G Immunoblot analysis of ectopic HIF2α protein levels in 293T cells expressing ectopic wild type (WT) USP33 or the catalytically dead (CD) USP33. HA-tagged HIF2α plasmids (0.5 µg) were introduced into 293T cells alone or together with GFP-tagged WT or CD USP33 plasmids (0.2 µg). Levels of ectopic HIF2α-HA and GFP-USP33 were analyzed 48 hours post transfection. Expression of the wild type USP33 but not the catalytically dead USP33 increased the ectopic HIF2α protein levels.
Figure 3A, Co-immunoprecipitation (Co-IP) to detect the interaction between endogenous HIF2α and USP33 in GSCs in response to low oxygen. GSCs were cultured under 20% or 5% oxygen for 24 hours before harvest for the Co-IP. Cell lysate was subjected to immunoprecipitation with anti-HIF2α antibodies. Co-immunoprecipitated products were immunoblotted with the indicated antibodies. An increased interaction between HIF2α and USP33 was detected in GSCs cultured under 5% oxygen relative to 20% oxygen.D Co-immunoprecipitation (Co-IP) to detect the interaction between endogenous HIF2α and USP33 in GSCs in response to CoCl2 treatment. GSCs were treated with CoCl2 (300 µM) for 12 hours before harvest for the Co-IP. Cell lysate was subjected to immunoprecipitation with anti-USP33 antibodies. Co-immunoprecipitated products were immunoblotted with the indicated antibodies. An increased interaction between HIF2α and USP33 was detected in GSCs treated with CoCl2 mimicking hypoxia.G Co-immunoprecipitation to detect the interaction between HIF2α and the wild-type (WT) or the catalytically dead (CD) USP33. Ectopic HA-tagged HIF2α were expressed in 293T cells with GFP-tagged wild-type or catalytically dead USP33. Cell lysates were subjected to immunoprecipitation with anti-HA antibodies. Co-immunoprecipitated products immunoblotted with the indicated antibodies. The catalytically dead USP33 relative to the wild type USP33 showed a stronger affinity to HIF2α.
Figure 4A Immunoblot analysis of the serine/threonine phosphorylation (pS/T) status of HIF2α in GSCs in response to 5% oxygen. GSCs were cultured under 20% or 5% oxygen for 24 hours, and then harvested for immunoprecipitation with anti-HIF2α antibodies or IgG control. Immunoprecipitated endogenous HIF2α were immunoblotted with anti-pan-pS/T antibodies. An increased pS/T of HIF2α was detected in GSCs cultured under 5% oxygen relative to 20% oxygen.D Co-immunoprecipitation to detect the interaction between endogenous HIF2α and USP33 in GSCs after inhibition of ERK1/2 activity. GSCs were cultured under 20% or 5% oxygen for 24 hours, then treated with the MEK inhibitor U0126 (10µM) for 30 minutes to inhibit ERK1/2 activity, and harvested for immunoprecipitation with anti-USP33 antibodies. Co-immunoprecipitated products were immunoblotted with the indicated antibodies. Relative to 20% oxygen treatment, 5% oxygen treatment promoted the interaction between HIF2α and USP33 in GSCs. However, inhibition of ERK1/2 activity by U0126 treatment suppressed the interaction between HIF2α and USP33.G Co-immunoprecipitation to determine the serine phosphorylation sites in human HIF2α responsible for its binding to USP33. Ectopic GFP-tagged USP33 along with HA-tagged wild type HIF2α or HIF2α mutants with indicated serine to alanine point mutations were expressed in 293T cells. Cell lysates were subjected to immunoprecipitation with anti-HA agaroses Co-immunoprecipitated products were immunoblotted with the indicated antibodies. The S484A mutation largely attenuated the interaction of HIF2α with USP33, indicating that the serine 484 site in HIF2α was the most important phosphorylation site for the interaction between HIF2α and USP33.
Figure 5B Representative images of tumorsphere formation of T387 GSCs expressing USP33-targeting shRNA (shUSP33) or non-targeting shRNA (shNT). Twenty-four hours after lentiviral infection, T387 GSCs expressing shUSP33 or shNT were planted in 96 well plates at the density of 2,000 cells per well and cultured for 48 hours under normoxia (20% O2) or hypoxia (5% O2). Disruption of USP33 inhibited GSC tumorsphere formation in normoxia and dramatically suppressed GSC tumorsphere formation in hypoxia. Scale bar, 200 μm.E Cell titer assays showing cell growth of T387 GSCs expressing shUSP33 or shNT in normoxia or hypoxia. GSCs were transduced with shNT or shUSP33 through lentiviral infection for 24 hours, and then split into 96 well plates at the concentration of 2,000 cells per well. Cell titer was determined by the Glo luminescent cell viability assay kit (Promega) at the indicated time points. Disruption of USP33 inhibited GSC growth in normoxia and hypoxia. The experiment has been repeated three times. The presented curves were based on three technical replicates. *, p < 0.05; **, p < 0.01; ***, p < 0.001 (mean ± s.e.m.; two tailed unpaired t-test).F Representative immunofluorescent staining of the apoptotic marker cleaved caspase 3 in T387 GSCs expressing shUSP33 or shNT in normoxia or hypoxia. GSCs were attached to hESC-Qualified Matrix (Corning) in 6-well plates at the concentration of 50,000 cells per well. Forty-eight hours post infection with shUSP33 or shNT lentiviruses, cells were stained for cleaved caspase 3 (green) and nuclei (blue). Scale bar, 80 μm.
Figure 6C, Representative images of autonomous fluorescent signals of 4HRE-d2GFP in xenografts derived from or shUSP33- or shNT- expressing T387 GSCs transduced with 4HRE-d2GFP. Scale bar, 200 μm.E, Representative images of autonomous fluorescent signals of 4HRE-d2GFP (green) and immunofluorescent staining of the stem cell marker SOX2 (red) in xenografts derived from T387 GSCs transduced with 4HRE-d2GFP. More GFP signals were detected in the SOX2+ cells compared with the SOX2- cells, suggesting a stronger hypoxia response in GSCs relative to NSTCs. Scale bar, 200 μm.G, Representative images of immunofluorescent staining of the apoptotic marker cleaved caspase 3 (red) and autonomous fluorescent signals of 4HRE-d2GFP (green) in xenografts derived from T387 GSCs transduced with 4HRE-d2GFP. The GFP+ population had much less apoptosis relative to the GFP- population, suggesting that hypoxia response inhibited cell apoptosis. Scale bar, 200 μm.
Figure 7B Kaplan-Meier survival curves of mice bearing GBMs derived from T387 GSCs expressing shUSP33 or shNT from (A). Disruption of USP33 extended the survival of mice bearing GSC-derived GBM tumors. (n= 5 mice for each group; shUSP33#42 vs shNT, p = 0.0185; shUSP33#45 vs shNT, p = 0.0027; two-tailed log-rank test).E, F Immunofluorescent analysis (E) and statistical quantifications (F) of the cell proliferation marker Ki67 in xenografts derived from T387 GSCs expressing shUSP33 or shNT. Disruption of USP33 in GSCs reduced cell proliferation in GBM xenografts. Scale bar, 80 μm. (n = 5 tumors for each group; ***, p < 0.001; mean ± s.e.m.; two tailed unpaired t-test).
Figure 1 A. HeLa cells released from double thymidine synchronization in early S phase were treated with 5-azadC for 30 min, washed and collected at the indicated times. Soluble and chromatin-enriched fractions were immunoblotted with indicated antibodies.  E. HeLa/GFP-DNMT1 cells transfected with indicated siRNAs were processed as in (D).  H. Representative images of U2OS cells transfected with indicated siRNAs followed by mCherry-RNF4 expression plasmid. Cells were treated with 5-azadC in the presence or absence of SUMOi, fixed 2 h later, pre-extracted and co-immunostained with DNMT1 and SUMO2/3 antibodies. Scale bar, 5 μm.  J. GFP-tagged DNMT1 from extracts of HeLa/GFP-DNMT1 cells treated or not with 5-azadC was immobilized on GFP-Trap agarose, subjected to stringent washing to remove proteins non-covalently bound to GFP-DNMT1 and incubated with recombinant HA-ubiquitin, E1 and E2 (UbcH5a) enzymes and RNF4 proteins (STUbL reaction) at 37 °C for 1 h. Samples were then subjected to immunoblotting to assay for RNF4-dependent STUbL activity towards GFP-DNMT1.