EMBO/SourceData huggingface dataset:
figf6p53 inhibition induces autophagy by ER stress (a-c) WT HCT116 cells were transiently transfected with GFP-LC3, treated with PFT-α for 2, 4 or 6 h and subjected to immunofluorescence staining to observe the colocalization of GFP-LC3+ puncta with the ER marker ERp57 (a) or a mitochondrial marker Complex III (b). Note that cells with GFP-LC3+ puncta often contain scarce amounts of ERp57 (white arrows) after prolonged incubation with PFT-α. The percentage of colocalization (means ± s.d., n = 3 experiments with 50 images per experiment) was determined by confocal microscopy (c).p53 inhibition induces autophagy by ER stress (a-c) WT HCT116 cells were transiently transfected with GFP-LC3, treated with PFT-α for 2, 4 or 6 h and subjected to immunofluorescence staining to observe the colocalization of GFP-LC3+ puncta with the ER marker ERp57 (a) or a mitochondrial marker Complex III (b). Note that cells with GFP-LC3+ puncta often contain scarce amounts of ERp57 (white arrows) after prolonged incubation with PFT-α. The percentage of colocalization (means ± s.d., n = 3 experiments with 50 images per experiment) was determined by confocal microscopy (c).(d) eIF2α phosphorylation in WT or p53−/− HCT116 cells treated with PFT-α (n = 5).(e, f) WT HCT116 cells (e, f) or p53−/− HCT116 cells (f) were transfected with GFP-LC3, plus a control siRNA or the indicated combination of IRE1α- and/or p53-specific siRNA, and treated with PFT-α, thapsigargin, tunicamycin or brefeldin A.(g) GFP-LC3-transfected WT or ire1α−/− MEF were treated with PFT-α. Columns in e-g show means ± s.d. of 3 independent experiments (*P 0.05).
figf7Kinetics of p53 degradation (a) and induction of GFP-LC3 puncta (b) in WT HCT116 cells cultured in complete medium in the presence of rapamycin (Rapa), tunicamycin (Tn), lithium (Li) or in nutrient-free medium (NF).(c) WT HCT116 cells transfected with control or HDM2-targeted siRNAs were cultured in the presence or absence of MG132 for 3 h, followed by the treatment with autophagy inducers for 6 h (Tp, thapsigargin; other abbreviations as in b). The abundance of p53 and HDM2 was determined by immunoblotting analysis and the percentage of cells showing accumulation of GFP-LC3 in vacuoles (GFP-LC3vac) was determined.(d) Effects of HDM2 inhibitors on p53 protein levels and autophagy. WT HCT116 were left untreated or treated with Nutlin-3, RITA and/or the indicated autophagy inducers, followed by the p53 immunoblot or immunofluorescence microscopy to visualize GFP-LC3 redistribution.(e) Effect of MG132 and HDM2 siRNA on autophagy of WT and p53−/− HCT116 cells.(f) Failure of HDM2 inhibitors to prevent autophagy induced by the absence of p53. Nutlin-3 and RITA were added to p53−/− HCT116 cells, followed by quantification of GFP-LC3 puncta.(g) Effect of WT and ubiquitination-resistant p53 on autophagy. p53−/− HCT116 cells were transfected with GFP-LC3 alone or in combination with different concentrations of pcDNA3.1, WT p53 or p53 lacking the ubiquitination site at amino acids 13-19 (p53ΔI), then treated with rapamycin, tunicamycin or thapsigargin. Thereafter, p53 expression and GFP-LC3 puncta were quantified.(h) Depletion of Atg5 or Beclin 1 does not prevent p53 degradation triggered by rapamycin or ER stressors. In WT HCT116 cells transfected with siRNA targeting Atg5 or Beclin 1, p53 levels were determined by immunoblot analysis after 6 h of treatment with rapamycin, tunicamycin or thapsigargin.
Figure 1B. RIBEYE mutations do not alter mouse survival. Data show surviving post-weaning mice (at >P21) derived from matings between mice heterozygous for the RBEKI allele (dark red) or the RBEKO allele (bright red) normalized for the total number of mice (absolute numbers per genotype/absolute number of all mice per respective breeding strategy) The expected Mendelian ratio is indicated by the dashed line. Statistical analysis using the 2-test revealed no statistical difference between wild-type and mutant mice (RBEKI allele p=0.33; RBEKO allele p=0.11).C. Representative immunoblot of retina homogenates from homozygous RBEWT/WT, RBEKI/KI and RBEKO/KO mice probed with antibodies to CtBP2 (to detect the B-domain of RIBEYE and CtBP2) and to EGFP (to detect GCamP3 in the RIBEYE A-domain GCamP3 fusion protein referred to as RIB-G3).D. Measurements by RT-PCR of the relative abundance of CtBP2 and RIBEYE mRNAs using an assay that simultaneously measures both mRNAs in retina and in brain from control wild-type mice (RBEWT/WT), KI-mice expressing the RIBEYE-A-domain fusion protein with GCamP3 (RBEKI/KI), and KO mice (RBEKO/KO). These measurements were performed to test the relative expression of RIBEYE and CtBP2 in retina, and to examine whether the RIBEYE A-domain KO impairs CtBP2 expression in brain, which expresses little RIBEYE. Assays are based on a qRT-PCR strategy detecting mRNAs containing the spliced connection between exon 2 and 3 which is common to both transcript isoforms (RIBEYE and CtBP2). Statistical analyses were performed using Student's t-test; data are presented as mean ± SEM (***, p<0.001; n=4 mice per genotype).E. Representative immunofluorescence labeling of cryostat sections from littermate wild-type and RBEKI/KI mice for EGFP (green, to detect GCamP3 in RIB-G3) and SV2 (red, to label synapses) demonstrates expression of the A-domain/GCamP3 fusion protein in knockin mice (OPL, outer plexiform layer; INL, inner nuclear layer; IPL, inner plexiform layer; GCL, granule cell layer). Scale bar = 5 µm.F. Levels of CtBP2 and of synaptic proteins in retina homogenates from littermate RBEWT/WT and RBEKO/KO mice. Levels were determined by quantitative immunoblotting using fluorescently labeled secondary antibodies; results are normalized to loading controls depending on molecular weights (actin, fodrin, VCP, and GDI) and to wild-type controls. Statistical analyses were performed using Student's t-test; data are presented as mean ± SEM (*, p<0.05; n=4 mice per genotype).G. Immunofluoresence labeling for CtBP2 (green, to label RIBEYE) and mGluR6 (red, to label photoreceptorsynapses) in cryostat sections from littermate RBEWT/WT and RBEKO/KOmouseretinas demonstrates that the KO abolishes RIBEYE expression (OPL, outer plexiform layer). Scale bars: 5 µm.
Figure 2A. Overview of the synaptic organization of the retina in RBEWT/WT and RBEKO/KOmice. Cryostat sections from littermate mice were labeled by double immunofluorescence for the RIBEYE B-domain (CtBP2; green) and SV2. Scale bar: 20 µm; abbreviations: ONL, outer nuclear layer; OPL, outer plexiform layer; INL, inner nuclear layer; IPL, inner plexiform layer; GCL, ganglion cell layer.B. Double immunofluorescence staining of retinas from RBEWT/WT and RBEKO/KO mice for PSD95 (green, to label postsynaptic specializations) and mGluR6 (red, to label specifically postsynaptic sites formed by bipolar neurons in photoreceptorsynapses). Abbreviations are as in A. Scale bars: 20 µm (left and right overview), 5 µm (left panel magnification), 2 µm (right panel magnification).C. Same as B, except that retinas were stained for PKCα (green, to label bipolar neurons) and PSD95 (red, to label amacrine cells).
Figure 4A. Transmission EM demonstrates the absence of synaptic ribbons in presynaptic terminals of photoreceptorribbon synapses in RBEKO/KOmice, while synaptic ribbons are readily visible in the terminals of RBEWT/WTmice. Asterisks in A2 and A3 denote photoreceptor active zones of RBEKO/KOmice in which the synaptic ribbon is absent. Except for the absence of synaptic ribbons, the ultrastructural appearance of the presynaptic terminals is comparable to that of RBEWT/WTmice. Abbreviations: sr, synaptic ribbon; pre, presynaptic; post, postsynaptic. Scale bars: 500 nm.B. Transmission EM demonstrates absence of synaptic ribbons in presynaptic terminals of bipolar cellribbon synapses in RBEKO/KOmice, while synaptic ribbons are readily visible in the terminals of RBEWT/WTmice. Except for the absence of synaptic ribbons, the ultrastructural appearance of the presynaptic terminals is comparable to RBEWT/WTmice. Abbreviations are the same as in A. Scale bars: 1 µm (B1, B2, B4, B5); 300 nm (B3, B6).
Figure 7A. Representative mEPSCs recorded from AII cells in wild-type (black) and RIBEYE KO mice (red). The insets in dashed boxes show mEPSCs on expanded scales, while the inset in a continuous box on the right shows the averaged mEPSC waveforms (average of 100-200 isolated mini events) of the example cells. Calibration bars apply to wild-type and mutant EPSCs.B. RIBEYE KO does not alter fundamental parameters of mEPSCs. Summary graphs show mean mEPSC frequency, amplitude, integrated charge, rise time, and decay time constant. Note that the only excitatory inputs into AII amacrine cells is provided by bipolar cell synapses.C and D. RIBEYE KO renders mEPSCs sensitive to the slow Ca2+-buffer EGTA (C, representative mEPSCs traces recorded from AII cells after 30 minutes incubation in DMSO or EGTA-AM [0.2 mM]; D, summary graphs of the mean mEPSC frequency (left) and amplitude (right) after incubation in DMSO or EGTA-AM).E and F. mEPSCs in AII amacrine cells are largely triggered by Ca2+-influx via presynaptic L-type Ca2+-channels (E, representative mEPSCs traces recorded in regular [2 mM] or reduced extracellular Ca2+-concentration [0.3 mM], or in the presence of nimodipine [50 µM] in regular Ca2+; F, summary graphs of the mean mEPSC frequency and amplitude under the conditions described for E).G and H. mEPSCs in AII amacrine cells are suppressed by the fast Ca2+-buffer BAPTA (G, representative mEPSCs traces recorded after 30 min incubations with DMSO or BAPTA-AM [30 µM]; H, summary graphs of the mean mEPSC frequency and amplitude under the conditions described for G).
Figure 1(A) Proof-of-principle experiment. Time-lapse images show overexpression of Myc-tagged CPAP-WT (i) or CPAPΔT (ii) has no effect on two centrosome-containing MCF10A cells (-Dox, two centrosomes). The cells were imaged from interphase to Cytokinesis. Bar graph at right quantifies mitotic duration of cells overexpressing CPAP-WT and CPAPΔT. We define mitotic duration as time consumed from the onset of cell rounding until cytokinesis. Number of cells (n) analyzed in each condition is indicated at the top of each bar. Number of independent experiments (N), (N)=3. Error bars, mean ± SEM. Unpaired t-test. CPAP-WT (iii) or CPAPΔT (iv) expressing extra centrosome-containing MCF10A cells (+Dox, extra centrosomes). Note compared to CPAP-WT expressing centrosomes (iii) CPAPΔT expressing centrosomes nucleate enhanced levels of microtubule asters already at prophase-like stage (iv). White arrows indicate centrosomal dots. Red arrows indicate centrosomes nucleating microtubule asters causing multipolar spindles. Scale bar, 2µm. Bar graph at right quantifies mitotic duration and percentage of cells exhibiting prolonged mitosis in cells expressing CPAP-WT and CPAPΔT. (N)=3. Error bars, mean ± SEM. Unpaired t-test ***P < 0.0001(B-D) Fixed cell images showing the expression of CPAP-WT (top panel) and CPAPΔT (bottom panel) in extra centrosome containing MCF10A (+Dox, extra centrosomes), MDA-MB-231 and H1975T790M cells. Note, in CPAP-WT expressing cells, clustered extra centrosomes remain inactive with no or reduced microtubule nucleation. On the other hand, CPAPΔT expression enhances microtubule nucleation in extra centrosomes (arrows) and preventing them from clustering at G2-like interphase and mitosis. Cells were stained with CPAP (GFP), microtubules (α-tubulin, red), Cep152 (magenta). Scale bar, 2µm(E) Bar graph quantifies percentages of mitotic cells exhibiting multipolar spindles upon CPAP-WT or CPAPΔT expression. (N)=3. Error bars, mean ± SEM. Unpaired t-test **P < 0.001(F) Subcutaneous xenograft tumor volume measurements of MDA-MB-231 cells expressing CPAP-WT (red) as control or CPAPΔT (blue) in nude mice. (i) Bar graph at right shows total tumor volume reduction at day 22. (ii) Each condition used 4 mice each containing 4 xenograft tumors. Error bars, mean ± SEM with n = 16 for CPAP-WT and n = 16 for CPAPΔT. Unpaired t-test ***P < 0.0001.
Figure 2(A) 1H NMR spectra of free CCB02 (black) and bound to tubulin in 50:1 ratio (orange). Broadening of CCB02 proton peaks indicate its binding ability to tubulin(B) NOESY spectrum recorded for a solution comprising tubulin (6.5µM), CPAP peptide (400µM) and CCB02.1 (200µM) with 70ms mixing time. The signals colored in green and (highlighted by boxes) correspond to inter-ligand trNOE signals arising due to protein-mediated spin-diffusion (INPHARMA NOEs), while the black peaks represent intra-ligand trNOE signals.
Figure 3(A) 14 day CCB02 treatment of MDA-MB-231, HCC827-GR, Calu-6 and MCF10A (+Dox, extra centrosomes) mostly eliminated cells with extra centrosomes. At the end of the treatment, cells were fixed and stained for centrosomes. Bar graph shows the percentage of cells displaying two- and more than two centrosomes. 'Vehicle' at the bar graph indicates percentages of cells with extra centrosome Note that percentages of cells containing more than two centrosomes are significantly reduced upon CCB02-treatment (open bars). Data represent mean ± SEM of three independent experiments. (N)=3, (n=70). p values were obtained using unpaired t test **P < 0.001, ***P < 0.0001(B) CCB02 treatment prevents centrosome clustering in HCC827-GR cells. Activated centrosomes (arrows) fail to cluster leading to multipolar mitosis. Cells were stained with Cep152 (green), CPAP (magenta) and microtubules (α-tubulin, red). Scale bar, 2µm, Insets, 0.5µm.Time-lapse images show the effect of CCB02-mediated centrosome activation in cell cycle progression of MCF10A (+Dox, extra centrosomes) (C cells. White arrows indicate centrosome dots. Red arrows (in CCB02-treated cells) indicate activated centrosomes with enhanced microtubule intensity compared to vehicle treated cells. Note, centrosome activation, declustering and prolonged multipolar mitosis occur only with CCB02 treatment. Cartoons of a cell with extra centrosomes below to the panel (C) represent various events occurring upon vehicle or CCB02 treatment. Scale bar, 2µm. Bar graphs at right to panel (C quantifies mitotic duration (ii), quantifies microtubule intensity prior to mitosis (iii) and depicts relative events occurring in cells treated with vehicle or CCB02 (iv) At least 100 cells were analyzed in each condition. (N)=3. Error bars, mean ± SEM. Unpaired t-test **P < 0.001, ***P < 0.0001Time-lapse images show the effect of CCB02-mediated centrosome activation in cell cycle progression o HCC827-GR (D) cells. White arrows indicate centrosome dots. Red arrows (in CCB02-treated cells) indicate activated centrosomes with enhanced microtubule intensity compared to vehicle treated cells. Note, centrosome activation, declustering and prolonged multipolar mitosis occur only with CCB02 treatment Bar graphs at right to pane (D) quantifies mitotic duration (ii), quantifies microtubule intensity prior to mitosis (iii) and depicts relative events occurring in cells treated with vehicle or CCB02 (iv). At least 100 cells were analyzed in each condition. (N)=3. Error bars, mean ± SEM. Unpaired t-test **P < 0.001, ***P < 0.0001
Figure 4(i) Experimental strategy to test if the effect of CCB02 is CPAP dependent in MCF10A cells containing extra centrosomes (+Dox, extra centrosomes) (A Cells were treated with CPAP siRNA and control (scramble) siRNA for 48 hours. (ii) Western blots show depletion of CPAP when cells were treated with siRNA specific for CPAPExperimental strategy to test if the effect of CCB02 is CPAP dependent i MDA-MB-23 cell (B). Cells were treated with CPAP siRNA and control (scramble) siRNA for 48 hours. (ii) Western blots show depletion of CPAP when cells were treated with siRNA specific for CPAP(C) Fractions of cells containing centrosomes after siRNA treatment. 48 hours of siRNA treatment still contained a fraction of cells with extra centrosomes that were analyzed in the following experiments. Bar graph shows the percentage of cells with extra centrosomes in MCF10A (+Dox, extra centrosomes) in the presence of control siRNA or CPAP siRNA. Data represent mean ± SEM of three independent experiments. (N)=3, (n=300 cells per condition). p values were obtained using Ordinary One-way ANOVA test *P < 0.01, **P < 0.001(D) Effect of CCB02 in the presence of control siRNA and CPAP siRNA in MCF10A (i) MDA-MB-231 cells (ii) CPAP depletion does not prevent centrosomes from clustering (second rows of i and ii). Note, in CPAP depleted cultures, centrosomes are marked with Cep152 (green) where CPAP (magenta) is detected faintly. In CPAP depleted cells, CCB02 does not prevent extra centrosomes from clustering (fourth rows of i and ii). Note CCB02 does prevent extra centrosomes from clustering in cultures treated with control siRNA (third rows of i and ii). Cells are stained for Cep152 (green), CPAP (magenta), microtubules (α-tubulin, red) and DNA (DAPI, blue). Scale bar, 2µm(E) Bar graph shows the percentage of cells with multipolar mitosis. Higher percentage of multipolar mitotic cells is observed in control siRNA-treated cultures. Bar graph on right shows the percentage of cells with multipolar mitosis. Data represent mean ± SEM of three independent experiments. (N)=3, (n=680 cells). p values were obtained using unpaired t test. ***P < 0.0001(F) Bar graph shows the percentage of living (TUNEL-negative) and dyeing (TUNEL-positive) cells under various conditions tested. Higher percentage of TUNEL-positive cells is observed in CCB02-treated cultures. Data represent mean ± SEM of three independent experiments. (N)=3, (n=500 cells per condition). p values were obtained using Ordinary One-way ANOVA test *P < 0.01.
Figure 5(A) Interphase centrosomes of CCB02-treated two-centrosome containing MCF10A cells display an enhanced level of PCM proteins. CPAP (green) intensity remains same. Cells are stained for CPAP (green), PCM proteins (magenta) Cep152 (i), PCNT (ii) and CDK5RAP2 (iii) and microtubules (α-tubulin, red). Scale bars, 2µm for left panels and 0.2µm for right panels. Heat map images show intensity saturation (blue) for CPAP, Cep152, PCNT and CDK5RAP2 upon CCB02 treatment. Line graphs at right to each panels indicate the heat map intensity of single centrosomes of cells (given in boxes at heat map panels) treated with vehicle (blue line) or CCB02 (red line). Images were recorded with low laser excitation and high zoom factor(B) Bar graph quantifies relative intensity of CPAP-interacting proteins in interphase centrosomes compared to vehicle treatment. At least 150 centrosomes (for vehicle); 130 centrosomes (for CCB02) were analyzed in each condition. Error bars, mean ± SEM. (N)=3. Ordinary Two-way ANOVA test ***P < 0.0001(C) Immunopurification of CPAP complexes from CCB02-treated cell extracts. (i) CCB02 specifically prevents CPAP-Tubulin interaction. This allows CPAP to bind an enhanced amount of Cep152 and γ-tubulin. Control IP experiment is shown below. (ii) Plot showing PCM protein intensities co-immunoprecipitated with CPAP at various concentrations of CCB02 treatment. CPAP amount does not change with CCB02 treatment. Data represent mean ± SEM. (N)=3.
Figure 6(B-D) MT-regrowth assays at 0, 1.5 and 3.0 min using MCF10A (-Dox, two centrosomes), MCF10A (+Dox, extra centrosomes) and MDA-MB-231 cells. MT nucleation panel is shown in grey scale (inset images are inverted) and γ-tubulin is shown in red. Note that in contrast to vehicle treatment, CCB02 treatment caused centrosomes to nucleate an enhanced level of microtubules already at 1.5 min after induction of regrowth with simultaneous increase in γ-tubulin recruitment. All these cells were stained with γ-tubulin (red), microtubules (α-tubulin, grey) and DNA (DAPI blue). Scale bar, 2µm and insets, 0.5 µm. Bar graphs show MT and γ-tubulin intensities at 3 min after induction of MT regrowth. (N)=3. At least 80 centrosomes were considered to calculate intensities from each cell line. Error bars, mean ± SEM. Unpaired t-test **P < 0.001, ***P < 0.0001.
Figure 7(A) Bar graph quantifies relative intensity of PCM proteins at interphase centrosomes of cells treated with vehicle, CCB02, and known tubulin binders. Two centrosomes containing MCF10A (-Dox, two centrosomes) cells were used. Elevated PCM proteins intensities were detected only with CCB02 compared to vehicle treated cells. However, a slight increase in PCNT was observed with Docetaxel treatment. Number of centrosomes tested, n=100 (vehicle); n=100 (for CCB02, Taxol, Bacatalin III, Docetaxel and Vinblastine). (N)=3. Error bars, mean ± SEM. Ordinary Two-way ANOVA test **P < 0.001, ***P < 0.0001(B) CCB02 but not conventional tubulin binders (Taxol, Bacatalin III, Docetaxel and Vinblastine; concentrations used 30nM) causes activation of extra centrosomes and prevents them from clustering. MCF10A cells with extra centrosomes (+Dox, extra centrosomes) were used. In contrast to CCB02-treatment, interphase centrosomes of tubulin binders-treated cells consistently display clustered centrosomes. Note, disrupted mitotic spindles were observed in tubulin binders-treated cells due to their general toxicity to microtubules. Cells were stained with CPAP (green), Cep152 (magenta) and microtubules (α-tubulin, red). Scale bar, 2µm. Three independent experiments (N)=3 with each at least 100 cells were examined per treatment(C) Bar graph quantifies percentages of cells exhibiting multipolar spindles in interphase and mitosis of vehicle, CCB02 and conventional tubulin binders-treated cells. At least 150 cells were analyzed for each independent experiment (N)=3. Error bars, mean ± SEM. Ordinary Two-way ANOVA test **P < 0.001(D) Kymographs (i) and averaged microtubule polymerization velocities mediated by vehicle and CCB02. Graph below represents the microtubule growth velocities mediated by vehicle (red) and CCB02 (blue) during microtubule end-tracking assay (ii). CCB02 does not alter the microtubule growth although there is a slight increase in growth at 5µM. At least 75 filaments were analyzed for each condition. The error bars represent mean ± SEM of three independent experiments (N)=3(E) Snap-shot images show the effect of CCB02 on microtubule dynamics in two-centrosome containing MCF10A cells. The microtubule was stained with SiR-tubulin and +end tip of microtubule was marked with EB3-EGFP. A 5µM CCB02 did not alter localization and dynamics of EB3 at the microtubules indicating that the CCB02 does not affect microtubule dynamic At least, 50 cells were analyzed for each condition. Scale bar, 2µm(F) Box plots represent the speed (µm/sec) (i), lifetime (sec) (ii), and length (µm) (iii) of growing microtubule tracks in MCF10A cells treated with 1, 2 and 5µM of CCB02. At least, 60 filaments were analyzed from each cell from a total of 30-40 cells. (N)=3. Error bars in boxplots mean ± SD. Ordinary One-way ANOVA test was performed. Boxes in all plots show the growing microtubule parameters such as speed (µm/sec), lifetime (sec) and length (µm/sec). Horizontal lines in boxes show the median value. Whiskers at both extremes of boxes indicate minimum and maximum values.
Figure 8(A) Real time live imaging of NSCLC (H1975T790M) 3D spheroids with vehicle, 5µM erlotinib or 5µM CCB02. At the end of live imaging, spheroids were fixed and stained for F-actin (green). Arrow indicates invasive (vehicle-treated) and non-invasive (CCB02-treated) structures in spheroids. Scale bar, 100µm(B) Time series plot shows the spheroid growth rate measurements. CCB02 treatment prevents the spheroid growth rate by inhibiting the formation of invasive protrusions At least 10 spheroids were measured for each condition. Error bars, mean ± SEM. Unpaired t-test ***P < 0.0001(D) Antitumor activity of CCB02 in vivo. Left: Subcutaneous xenograft tumor volume measurements of H1975T790M (30mg/kg of weight, daily) in nude mice treated with vehicle or CCB02. Right: Bar graph shows total tumor volume at day 1 and day 24 of vehicle or CCB02 treated xenograft. Error bars, mean ± SD with n = 8 for control vehicle and n = 8 for CCB02 treatment. Unpaired t-test *P < 0.01.