EMBO/SourceData huggingface dataset:
Figure 1A. Representative fluorescence micrographs of HeLa cells treated with 250 μM lysosomotropic drug LLOMe or equal volume of DMSO (Ctrl) for 1 h before fixation and immunostained with Hoechst (blue), anti-CHMP4B (green), anti-GAL3 (red) and anti-LAMP1 (white) are presented. Cells treated with LLOMe show increased recruitment of ESCRT-III protein to lysosomes when compared to Ctrl cells. Number of foci per cell were quantified and are indicated as mean ± SD. Data from >86 cells per condition from three independent experiments. CHMP4B, GAL3, LAMP1 foci per cell (Ctrl versus LLOMe treatment): p=0.0398, p=0.0033, p=0.2400 (Student"s t‐test), respect Data information: Scale bars: 10 μm and 1 μm (inset)B. HeLa cells stably expressing CHMP4B-eGFP and mCherry-Galectin3 treated as in (A) and stained with CD63 antibody are shown. Number of foci per cell were quantified and are indicated as mean ± SD. Data is quantified from >87 cells per condition from three independent experiments. CHMP4B, GAL3, CD63 foci per cell (Ctrl versus LLOMe treatment): p=0.0111, p=0.0050, p=0.3793 (Student"s t‐test), respect Data information: Scale bars: 10 μm and 1 μm (inset)
Figure 4A. HeLa cells stably expressing CHMP4B-eGFP were treated with 250 μM LLOMe and 75 nM Lysotracker DND-99 and fixed at different time points as indicated. After 10 min of LLOMe treatment CHMP4B is recruited whereas the number of Lysotracker positive foci is reduced. After 30 min, lysosomes gain back functionality (judging by the increased number of Lysotracker foci) and appear recovered after 1 h indicating that the ESCRT complex is able to seal the damaged endolysosomal membranes. Representative confocal images for each time point are shown. Scale bars: 5 μmB. Quantification graph (>250 cells per condition from four independent experiments) showing CHMP4B and Lysotracker positive foci per cell at different time points. Error bars correspond to 95% confidence intervalsC. Quantification graph showing dynamics of Lysotracker recovery in control (siCtrl) and both TSG101 and ALIX depleted cells. HeLa cells stably expressing CHMP4B-eGFP were co-transfected with siRNAs against TSG101 and ALIX. 48 h post-transfection, cells were pre-treated for 20 min with 75 nM Lysotracker Deep-Red, which was used as a read-out. While the decrease in the number of Lysotracker spots is quickly recovered in siCtrl, simultaneous depletion of ALIX and TSG101 leads to a severe impairment in lysosomal repair. Data from >40 cells per condition from four independent live-cell imaging experiments are shown. Graph is normalized to the area occupied by the cells. Error bars correspond to 95% confidence intervals.
Figure 6A. HeLa cells stably expressing CHMP4B-eGFP and mCherry-Galectin3 were incubated with 250 μM LLOMe, fixed at different time points as indicated and stained for ubiquitin. As presented, CHMP4B is recruited before ubiquitin and Galectin3 upon lysosomal membrane damage Data information: Quantification graphs are normalized to the cell number where error bars represent 95% confidence intervals. Data were obtained from >150 cells per condition from three independent experimentsB. HeLa cells stably expressing CHMP4B-eGFP were treated as in (A) and stained for p62. CHMP4B is recruited before p62 on the damaged lysosomes. The number of LAMP1-positive foci appears stable independently of LLOMe treatment Data information: Quantification graphs are normalized to the cell number where error bars represent 95% confidence intervals. Data were obtained from >150 cells per condition from three independent experimentsC. Experimental setup as in (A and B) where HeLa cells stably expressing CHMP4B-eGFP and mCherry-Galectin3 were stained for LC3. As shown, CHMP4B is recruited prior to LC3 Data information: Quantification graphs are normalized to the cell number where error bars represent 95% confidence intervals. Data were obtained from >150 cells per condition from three independent experiments
Figure 7A. HeLa cells were transfected with different siRNAs as indicated. 48 h post-transfection cells were treated with 250 μM LLOMe for 3, 6, 10 hours harvested and stained for Annexin V. Cells were immediately processed for flow cytometry. Already after 3 h of treatment with LLOMe, cells co-transfected with TSG101+ALIX siRNA showed an increase in apoptotic cell death, whereas TSG101 siRNA transfected cells showed elevated Annexin V staining after 6 h of treatment Data information: Graphs show average data from a set of three independent experiments where >10,000 cells per condition were analyzed. Error bars represent SEM. Statistical significance was determined using one-way ANOVA test. p-values are presented where significant. *p-value≤ 0.05, **p-value≤ 0.01 and ***p-value≤ 0.001B. Experimental set up as in (A) with additional propidium iodide (PI) staining of transfected HeLa cells Data information: Graphs show average data from a set of three independent experiments where >10,000 cells per condition were analyzed. Error bars represent SEM. Statistical significance was determined using one-way ANOVA test. p-values are presented where significant. *p-value≤ 0.05, **p-value≤ 0.01 and ***p-value≤ 0.001
Figure 8A. HeLa cells stably expressing CHMP4B-eGFP were transfected with the mCherry-Galectin3 plasmid. 24 h later, cells were infected with WT Coxiella burnetti. Live-cell imaging started 24 h post-infection and several time points are indicated during the next 24 h of observatio Arrows indicate Coxiella-containing vacuole (DRAQ5 labeling) becoming positive for CHMP4B-eGFP and mCherry-Galectin3. Data information: Scale bars: 50 μmB. Bacterial viability and replication assay upon TSG101 KD. HeLa cells were treated with either siCtrl or with two different siTSG101 for 48 h. Then cells were infected with mCherry-Coxiella burnetii for 48 h before lysis and serial dilutions were made to infect Vero cells. 72 h later, infected cells were fixed, DAPI stained and processed for quantitative image analysis. Between 30 and 40 fields representing more than 9,000 cells per condition of three independent experiments were analyzed. Error bars represent SD. Statistical significance was determined using one-way ANOVA test. **p-value≤ 0.01 and ***p-value≤ 0.001.
Figure 1b - d) Comparative characterization of CHO cell bulk transfection cultures, selected for stable expression of the UnaG- or EGFP-encoding reporter constructs.b) Flow cytometry revealed efficient induction of green fluorescence, after treatment of both UnaG and EGFP-expressing CHO bulk cultures with CoCl2, while growth under hypoxia (1% oxygen) for 12 hours, selectively induced green fluorescence only in dUnaG expressing cells. Under normoxia (21% oxygen) only background fluorescence was observed.c) Assessment of the mean fluorescence intensity (MFI) to determine the activity of the 5xHRE-CMV promoter after 12 and 24hrs. Fluorescence intensity increased between 12 and 24hrs.d) Representative images of dUnaG- or dEGFP-expressing CHO cells grown either under normoxia (21% oxygen), CoCl2-treatment or hypoxia (1% oxygen) for 12 hours. Scale bars= 50µme) Fluorescence intensity in dUnaG- or dEGFP-expressing CHO cell bulks grown under increasingly hypoxic conditions of 10%, 5% and 1% oxygen for 24 hrs indicated efficient induction of the dUnaG sensor at oxygen concentrations below 5%.f) Maximal fluorescence of the UnaG-based hypoxia reporter in CHO cells grown at 1% oxygen for 24 hrs hours was only observed at serum concentrations of 5% FCS or higher, reflecting the dependence of UnaG on its serum cofactor bilirubin.
Figure 2b) Microscopic assessment of the averaged fluorescence intensity (AFI) of CHO cell bulk cultures stably expressing the indicated UnaG variants or destabilized EGFP. Expression under hypoxia was induced by incubation in 1% oxygen for 16 hrs and then culture was continued for 24 hrs under normoxia. Fluorescence hysteresis after switching to normoxia was markedly reduced in the singly-destabilized UnaG-variants, while the doubly destabilized doUnaG displayed the most rapid switching behavior, but the least brightness. To reduce phototoxicity, illumination intensity was kept minimal. Data points represent one viewfield of 425 µm2 ± SEM.c) Flow cytometry analysis of the induction and decay kinetics of the fluorescence intensity in CHO cells stably expressing either dUnaG or oUnaG. Open bars represent control cultures grown under normoxia. Solid bars indicate culture for 4, 8, 12, 16, 20 or 24 hrs under hypoxia (1% oxygen). To assess deactivation, cultures previously kept under hypoxia (1% oxygen) for 24hrs were shifted to normoxia (21% oxygen) for the indicated times. Error bars represent standard errors.d) Representative maximum intensity projections (MIPs) from the life cell cultures depicted in b. Cells were grown for the indicated times at hypoxic (1% oxygen) conditions and subsequently switched for the indicated times to normoxia (21% oxygen)(red arrows in b) to illustrate the dynamics of the different UnaG-based hypoxia sensors. Increasing destabilization is associated with reduced brightness but, also reduced background and improved switching behavior. Scale bars = 50 µm.
Figure 3a) UnaG-based hypoxia sensing is applicable in vivo as shown here using the human Gli36 glioblastoma model. 500 Gli36 glioblastoma cells, constitutively expressing mCherry and stably transfected with the HRE-dUnaG sensor construct, were stereotactically transplanted into the cortex of a SCIDmouse. Shown is a 30 µm cryosection of a growing tumor 10 days after transplantation. Tumor cells are distinguished from the surrounding cortex by mCherry expression. Blood vessels were contrasted by immunostaining against PECAM-1. Expression of dUnaG was visualized by its green fluorescence and predominates in areas with reduced vascular density (outlined by white line in the composite panel (bottom right).b) Representative area from the tumor shown in a), which is located outside the viewfield in a) positioned more closely to the tumor border. Also at the tumor border UnaG-expressing cells are preferentially observed at a distance to PECAM-1+ vessels.c) Areas of dUnaG expression correlate well with HIF-1α stabilization. Immunostaining for HIF-1α (cyan) revealed the predominantly nuclear localization of stabilized HIF-1α in cells that were also dUnaG-positive (green).d) Analysis of dUnaG expressing cells in c) for mCherry fluorescence and HIF-1α stabilization. dUnaG-positive cells were classified according to their average fluorescence intensity into background level and above background level expression for mCherry and HIF-1α The threshold was set in either case to channel 70 of 256 intensity channels. Using this classification >60% of UnaG positive cells displayed only background level mCherry fluorescence. On the other hand, >98% of the UnaG expressing cells also expressed HIF-1α , which together suggests that here UnaG acts preferentially as a hypoxia sensor in vivo.e) The dUnaG-based senor was efficiently applied in intravital microscopy. 500 Gli36 glioblastoma cells stably expressing mCherry and harboring the dUnaG-sensor construct were positioned at 200µm depth subcortically in a SCIDmouse and observed 4 days later through a cranial window using multiphoton microscopy. We noted two distinct areas of intense UnaG fluorescence (red lines). Shown is a MIP of a 60 µm z stack. The vasculature was contrasted by intravenous injection of non-functionalized Qdots.f) Depth color coding of the MIP shown in e) revealed the spatial relation between the vasculature, (contrasted by Qdots), areas of increased dUnaG expression (bordered by green lines) and tumor cells expressing residual levels of mCherry. The hypoxic areas were located towards the top of the imaged tissue cube and therefore at different levels compared to the large vessel at the lower left corner (red asterisk) and the smaller vessels with a more axial orientation (white arrows). Scale bars = 100µm
Figure 4b) Microscopic assessment of the averaged fluorescence intensity (AFI) in CHO cells stably transfected with the dUnOHR sensor. Hypoxia was induced by incubation in 1% oxygen for 18 hrs, then the culture was switched to normoxia for 24 hrs, followed by another 14 hrs hypoxia and finally normoxia again. As expected UnaG fluorescence is efficiently induced under hypoxia, while mOrange fluorescence only appears after the switch to normoxia only. The increase in both green and orange fluorescence is limited under normoxia by the subsiding HRE-mCMV promoter activity. This behavior is repeated in subsequent hypoxia / normoxia cycles. The increase in absolute fluorescence intensity is due to proliferation during the 72hrs culture period. Plotted is the average of the mean ± SEM.c) Visualization of the fluorescence of the dUnOHR reporter during alternating hypoxia / normoxia cycles as described in b.) MIPs of life cell cultures stably transfected with the dUnOHR sensor construct illustrate the temporally asynchronous fluorescence of UnaG and mOrange. Scale bars = 100 µm.
Figure 5a) Overview of a tumor induced by deep cortical deposition of approximately 500 Gli36 cells stably transfected with the dUnOHR sensor construct. The perimeter of the developing tumor (white line in the merged picture, lower right panel) was delineated by Hoechst 33342 staining. As observed for dUnaG the reoxygenation sensor was expressed in compact areas with low vascular density. Vascular endothelium was identified by PECAM-1 staining. 30 µm cryosection. Scale bar = 500µm.b) Details of the tumor shown in a). Sparse, distinct cells are characterized by intense green and orange fluorescence (shown as orange) and are located preferentially to the edge of the hypoxic phalanx (white arrows). A number of cells in close proximity of the nearest blood vessel display weak green and orange fluorescence (asterisks), indicative of previously hypoxic environment and subsequent reoxygenation. Scale bar = 50 µm.c) Recently reoxygenated cells (arrows) cluster at the edge of hypoxic areas and are often detected in the proximity of vessels with a homogeneous caliber (double arrows). Scale bar = 100 µm.d) Previously hypoxic cells, frequently undergo apoptosis after reoxygenation. We noted an accumulation of intensely orange fluorescing spots at the edges of compact UnaG positive areas. Scale bar = 50µm.e) TUNEL staining of tumor sections revealed that the tissue areas rich in intense mOrange aggregates colocalized with areas of increased apoptosis. Scale bar = 50µm.
Figure 1A-B. Correlation of MCU and MCUb expression levels with breast cancer clinical stages. Median-centered log2 mRNA expression levels of MCU and MCUb were collected from the TCGA breast cancer dataset (http://tcga-data.nci.nih.gov/docs/publications/brca_2012/). Data were plotted and analysed against tumor size (T1-T4) (A) and regional lymph node infiltration (N0-N3) (B), according to the AJCC Cancer Staging Manual (7th edition). Linear regression analysis with different stages was implemented. Parameters of linear regression are shown. Number of samples for each stage are shown in parentheses.C-E. MCU silencing reduces Ca2+mit uptake in TNBC cells. Cells were transfected with siMCU or siControl. After 48h, [Ca2+]mit uptake upon ATP (C, E) or Histamine (D) stimulation was measured (n=10). P-values: ***p= 0.0008, ***p<0.0001, ***p= 0.0001, respectively.F-H. MCU silencing impairs TNBC cell migration. Cells were transfected with siMCU or siControl. The day after transfection, a linear scratch was obtained on the cell monolayer through a vertically held P200 tip (time- point 0h). Cell migration into the scratched area was monitored 48 hours later. The covered area was measured and expressed as a percentage relative to 0-hour time-point (n=12). P-value: ***p<0.0001.I-K. Cell proliferation is mainly unaffected by MCU depletion. Cells were transfected with siMCU or siControl. Cell number was counted every 24 hours for 3 days (the 72-hour time point corresponds to the 48-hour time-point of wound healing assay). Results are expressed as ratio R/R0 where R0 is the number of cells at the time of transfection (0 hour time-point) (n=6). P-value: *p=0.05.
Figure 2A. Re-expression of mMCU rescues cell motility of MCU-silenced cells. Cells were transfected with siMCU or siControl. Ad-mMCU was used to re-express MCU (Ad-GFP was used as control). MCU protein expression was verified by western blot. The day after transduction a linear scratch was made (time-point 0h). Cell migration into the wounded area was monitored at 48 hour time-point and the covered area was measured (n=12). P-value: ***p<0.0001.B. MCU silencing blunts cell invasiveness. Stable shMCU and shControl-expressing spheroids were plated and let grow into collagen-I (0 hour time-point). Spheroid area was measured at 0-hour and 48-hour (n=8). Scale bar 300 μm. P-value: ***p=0.0003.C. MCU silencing reduces the clonogenic potential of MDA-MB-231 cells. Stable shMCU and shControl-expressing cells were plated at low confluence (2x103/well of a 6-well plate). After 7 days the number of colonies was counted (minimum 30 cells/colony, n=8). P-value: **p=0.0027.D. MCU depletion does not induce cell death. Cells were transfected with siMCU or siControl. 72 hours later, cell apoptosis and necrosis were measured by FITC-Annexin V and Propidium Iodide (PI) detection (Q1: PI positive, Q2: PI and FITC-Annexin V positive, Q3: PI and FITC-Annexin V negative, Q4: FITC-Annexin V positive. n=6).E. MCU depletion does not alter cell cycle. Cells were transfected with siMCU or siControl. 72 hours later, cell cycle distribution was monitored by Propidium Iodide (PI) detection (n=6).
Figure 3A. Tumor mass volume was measured at specific time-points until the day of sacrifice (day 39 post-injection for control, day 46 and 56 p.i. for MCU-/- cl.1 and cl.2, respectively). P-values: ***p=0.0001, ***p<0.0001.B. left: in vivo metastasis at the homolateral axillary area of three representative mice per group at the time of sacrifice. Right: total flux analysis. P-values: **p=0.01, *p=0.02.C. Lymph nodes weight at the time of sacrifice. P-values: ***p=0.0010, **p=0.0014.D. Human cytokeratin 7 (CK7) IHC staining of three representative lymph nodes per group. Scale bar= 500 µm.E. Left: images of three representative lungs per group collected ex vivo at the time of sacrifice. Right: total flux analysis. P-values: **p=0.0031, ***p= 0.0004.
Figure 4A-C. FLIM analysis of cellular NADH/NADPH levels. Fluorescence lifetimes of NAD(P)H autofluorescence in stable shControl and shMCU expressing cells were imaged. Representative images of the distribution of τbound on an intensity weighted pseudocolored scale (2.2-2.5 ns) are shown. Scale bars = 20 μm (A). Mean +/- SE of τbound (B) and relative NADH and NADPH intensities (C) calculated from equation in (Blacker et al., 2014) are shown (n=3). P-values: **p=0.01, **p=0.002, respectively.D-E. Measurement of the redox state of the NADH/NAD+ couple. Representative measurements of NADH intensity at steady state and at minimal and maximal reduced state (D). Percentage of the steady state redox state (E) (n=3).F. MCU depletion impairs the mitochondrial rate of ATP production. Cells were transfected with siMCU or siControl. 48 hours later, cells were treated with 5.5 mM 2-deoxy-D-glucose for 1 hour and cellular ATP levels were quantified (n=6). P-value: ***p=0.0009.
Figure 5A. Antioxidant treatments decrease cell migration. A linear scratch was obtained on cell monolayer through a vertically held P200 tip (time-point 0h). Cells were treated for 48 hours with N-Acetylcysteine (NAC) or Dithioerythritol (DTE). Cell migration into the wounded area was monitored at 48-hour time-point and the covered area was measured (n=12). P-values: **p=0.008, ***p<0.0001, **p=0.005.B. Scavenging of mitochondrial ROS decreases cell migration. A linear scratch was obtained on a cell monolayer through a vertically held P200 tip (time-point 0h). Cells were treated for 48 hours with 50 µM MitoTEMPO. Cell migration into the wounded area was monitored at 48 hour time-point and the covered area was measured (n=12). P-value: ***p<0.0001.C. MCU silencing does not affect matrix pH. Cell were transfected with siMCU or siControl and SypHer2 probe. 48 hours later, matrix pH was measured (n=22).D-E. Mitochondrial H2O2 levels are critically blunted after MCU depletion. Cells were transfected with shMCU or shControl, together with the ratiometric YFP-based biosensor pHyper-dMito (D) or the mitochondrial H2O2-sensitive HyPerRed probe (E). 48 hours later, H2O2 production was measured (n=35). P-values: *p=0.02, *p=0.05, respectively.F. Mitochondrial superoxide levels are critically blunted after MCU silencing. Cells were transfected with siMCU or siControl. 48 hours later, cells were loaded with the red dye MitoSOXTM and superoxide anion levels were measured (n=25). P-value: *p=0.04.G. Mitochondrial GSSG/GSH ratio is critically reduced after MCU silencing. Cells were transfected with shMCU or shControl, together with the mitochondrial targeted mitGrx1-roGFP2 probe. 96 hours later, the glutathione redox potential (EGSH) was measured (n=46). P-value: ***p<0.0001.
Figure 6A. MCU silencing reduces HIF-1α protein levels. Cells were transfected with siMCU or siControl. HIF-1α protein levels were detected 48 hours later.B. MCU silencing reduces MG132-mediated HIF-1α and hydroxylated HIF-1α protein accumulation. Cells were transfected with siMCU or siControl. 48 hours later, cells were treated with 10 μM of the proteasome inhibitor MG132. Left: Protein levels were revealed by western blot. Right: quantification by densitometry (n=5).C. ROS increase HIF-1α transcription. Cells were treated O/N with 100 µM paraquat to induce ROS production. HIF-1α mRNA levels were measured by RealTime-PCR (n=3). P-value: **p=0.002.D-J. MCU silencing reduces mRNA levels of HIF-1α, HIF-2α, and HIF-1α target genes. Cells were transfected with siMCU or siControl. mRNA expression was measured by RealTime-PCR (n=3). P-values: (HIF-1α) **p=0.0031, **p=0.009, (HIF-2α)**p=0.01, (LOX)***p=0.001, ***p=0.0005, (PDK1)*p=0.02, **p=0.009, (G6PI)*p=0.02, **p=0.005, (CA IX)**p=0.0026, **p=0.0022, (HK2) **p=0.0024, *p=0.03.K. HIF-1α overexpression rescues siMCU-mediated migration impairment. Cells were transfected with siMCU or siControl. Wild type (wt) and constitutively active (ca) HIF-1α were expressed by retroviral infection (pBABE was used as control). The day after transduction, cells were scratched (time-point 0h). Cell migration into the wounded area was monitored at 48 hour time-point and the covered area was measured (n=12). P-values: ***p<0.0001, *p=0.04.L-M. MCU expression levels correlate with HIF1α (L) and HIF1α-regulated genes (M). A linear model (lm) to test the power of MCU expression levels predicting the expression of HIF1α and HIF1α-regulated genes was calculated and plotted for each of the 532 samples of the TCGA database (see Figure 1). Equation and R2 values of the linear regression and significance indicating deviation from 0 are shown. The area of 95% prediction limit is shaded below and above the linear regression line. The HIF1α-regulated gene set was compiled from Broad Institute GSEA database (http://www.broadinstitute.org/gsea/msigdb/cards/V$HIF1_Q5.html, merged sets of V$HIF1_Q3 and V$HIF1_Q5).
Figure 1(C) Decreased levels of free carnitine and modified carnitine species in PKM2 KO cell lines as compared with their parental counterparts (n=4). Data information: Data are displayed as means ± SD. Statistical significance was assessed using two-tailed Student's t-test, ∗p < 0.05, ∗∗p < 0.01 and ∗∗∗p < 0.001. n.s means no significance.(E) Increased acetyl-CoA in PKM2 KO MCF7 and MDA-MB 231cells as compared with their parental counterparts (n=4). (F) Decreased total cholesterol in PKM2 KO MCF7 and MDA-MB 231cells as compared with their parental counterparts (n=3). ( Data information: Data are displayed as means ± SD. Statistical significance was assessed using two-tailed Student's t-test, ∗p < 0.05, ∗∗p < 0.01 and ∗∗∗p < 0.001. n.s means no significance.
Figure 2(G) Western blot analysis of TMEM33, ABCA1, SREBP1, HMGCR, SCAP, FASN, LDLR, FDFT1, I DI1, RNF5, INSIG 1 and 2, and Calnexin in PKM2 KO MCF7 and MDA-MB-231 cells, and their respective parental cells. Arrow indicates nuclear SREBP1. P: precursor, N: nuclear.