EMBO/SourceData huggingface dataset:
Figure 4A. Immunoblotting of indicated proteins in A375 cells 72 hr after treatment with siASNS, siSLC1A5, siSLC7A5, or a combination of siASNS and siSLC1A5, or siASNS and siSLC7A5.B. RT-qPCR analysis of indicated transcripts in melanoma cells after 36 hr treatment with siASNS, siSLC7A5, or both.C. Proliferation of melanoma cells over indicated times after treatment with siASNS, siSLC7A5, or both.D. GC-MS-based estimation of intracellular amino acid levels in A375 cells treated with siASNS, siATF4, or both (top left); siASNS, sicMYC, or both (top right); siASNS, siSLC1A5, or both (bottom left); or siASNS, siSLC7A5, or both (bottom right). The fold change is relative to NT-siRNA-treated A375 cells.Immunoblotting of indicated proteins in A375 cells 72 hr after indicated treatment (E),Immunoblotting of indicated proteins in A375 cells 72 hr after , treatment with siASNS, sicMYC, or bothImmunoblotting of indicated proteins in A375 cells 72 hr after indicated treatment with , siASNS, siSLC7A5, or both (G)Immunoblotting of indicated proteins in A375 cells 72 hr after indicated treatment with siASNS, BCH, or both (H)Immunoblotting of indicated proteins in A375 cells 72 hr after indicated treatment with siASNS, HA-GSK3-β (S9A), or both (I)Immunoblotting of indicated proteins in A375 cells 72 hr after indicated treatment with , siASNS or indicated combinations (J)Immunoblotting of indicated proteins in A375 cells 72 hr after indicated treatment with siASNS, siSLC3A2, or both (K).L. RT-qPCR analysis of indicated transcripts in melanoma cells after 36 hr treatment with siASNS, siSLC3A2, or both.M. Proliferation of melanoma cells over indicated times after treatment with siASNS, siSLC3A2, or both.
Figure 1(A) CRISPR-guided AID∆C protein could support CSR in Aicda-/- CH12F3 cells. Left, CRISPR-guided AID is schematically illustrated with each component listed. Right, CRISPR-guided AID initiated CSR levels to IgA. Blue arrows represent multiple CRISPR recognition sites. The number in the parentheses indicates CRISPR recognition sites in each S region. Three biological replicates are plotted by dots and mean with standard deviation (SD). Data information: For panels A one-way ANOVA followed by Dunnett's multiple comparisons test was used for significance assessment. For all panels, ****, p<0.0001; ***, p<0.001; **, p<0.01; *, p<0.05; ns, p>0.05.(B) CRISPR-guided AID generated breaks at the S region in Aicda-/- CH12F3 cells were quantitatively detected by PEM-seq. Top, schematic illustration shows the bait SaCas9 site at Iγ3 region and CRISPR-guided AID variants targeting sites at S regions. Bottom, percentages of translocation junctions between Iγ3 and Sμ or Sα regions are plotted as mean with SD of three biological replicates in the bar plot. Data information: For panels B, one-way ANOVA followed by Dunnett's multiple comparisons test was used for significance assessment. For all panels, ****, p<0.0001; ***, p<0.001; **, p<0.01; *, p<0.05; ns, p>0.05.(C) AID-AIDE58Q dimer proteins were expressed in AID-deficient CSR-activated B cells, AID dimer is schematically illustrated on top and CSR levels to IgG1 are shown. Three biological replicates are plotted by dots and mean with SD is shown. Data information: For panels C, one-way ANOVA followed by Dunnett's multiple comparisons test was used for significance assessment. For all panels, ****, p<0.0001; ***, p<0.001; **, p<0.01; *, p<0.05; ns, p>0.05.(D) CSR levels to IgA in Aicda-/- CH12F3-miniS cells with indicated AID variants or CRISPR-guided AID variants. Levels of CSR to IgA are plotted and mean with SD of three to six biological replicates. Data information: Unpaired two-tailed Student's t-test was performed for panel D. For all panels, ****, p<0.0001; ***, p<0.001; **, p<0.01; *, p<0.05; ns, p>0.05.(E) Mutation profiles of miniS region in Ung-/-Msh2-/-Aicda-/- miniS cell lines complemented with indicated AID. Mutation frequency at each nucleotide along the 756-bp miniS region is plotted as a bar graph with green error bars, representing mean with standard error of the mean (SEM) of three biological replicates. Positions of AID-preferred AGCT and other RGYW motifs are marked with orange and yellow respectively under each plot.(F) Mutation profiles of miniS region in Ung-/-Msh2-/-Aicda-/- miniS cell lines expressing CRISPR-guided AID variants. Mutation frequency at each nucleotide is plotted as mean with SEM of three biological replicates in the bar graph with green error bar. Plots are labeled as in (B). The sgRNA targeting position is indicated with blue lines at the bottom.
Figure 2(A) Representative images showing the localization of AID (green), AIDR190X (green), and endogenous IgH loci (red) in nucleofected Aicda-/- CH12F3 cells. The IgH loci are visualized using Sμ-gRNA and indicated by white arrows. An illustration of CRISPR-Sirius IgH locus visualization is shown on top. Scale bar, 5 µm.(B) OptoDroplet formation in CH12F3 cells. Schematic illustration of light-induced optoDroplet system is depicted on top. AID variants were tagged to the N terminus of the optoDroplet construct and blue light was employed to promote the formation of puncta three times followed by imaging each time. Representative images after the third blue light activation in Aicda-/- CH12F3 cells with the indicated AID variants are shown at the bottom. White dashed line and green line depict the shapes of nucleus and nucleolus based on Hoechst staining or GFP-FBL, respectively. Scale bar, 5 µm.(C) Representative images showing optoDroplet formation of indicated AID variants in HEK293T cells. CRM1 inhibitor (CRM1i) was used for selective trapping of AID in nuclei. Scale bar, 5 µm.(D) The fluorescence intensity of indicated AID variants in each HEK293T cell nucleus was measured and normalized relative to the fluorescence intensity of the whole cell. Data are shown as box plots. Values between lower quartile and upper quartile are represented by box ranges, a horizontal line within the box represents the median, and whisker extends from the minimum value to the maximum value. "+" indicates the mean level. Each dot indicates one cell, and more than 20 cells represent two biological replicate samples were counted. One-way ANOVA followed by Dunnett's multiple comparisons test was performed. ****, p<0.0001; *, p<0.05; ns, p>0.05.(E) Intensity recovery lines for optoAID∆C droplets in FRAP experiment in HEK293T cells. Bleaching occurs at t = 0 s. The background-subtracted fluorescence intensities are normalized by pre-bleach values. The mean with SD of 10 pairs of optoAIDR190X and 10 pairs of optoAIDcry is shown, respectively.(F) Formation of puncta in primary B cells complemented with AID-FUS-GFP or AID-FUSm-GFP. FUSm contains 13 mutations on either Y or R residue. Left: Representative images showing cellular localization of AID-FUS-GFP and AID-FUSm-GFP with and without CRM1 inhibitor (CRM1i) treatment in Aicda-/- primary B cells. Scale bar, 5 µm. Right: Quantification of the number of cells with condensed puncta (3 biological replicates). Unpaired two-tailed Student's t-test was performed. ****, p<0.0001.(G) CSR levels to IgG1 in activated Aicda-/- primary B cells complemented with the indicated protein. Left, representative flow cytometry plots measuring CSR to IgG1. Co-expressed GFP was used to indicate the infected fractions. Right, the mean with SD of three biological replicates is shown in the bar plot. Unpaired two-tailed Student's t-test was performed. ****, p<0.0001.
Figure 3(A) Representative immunofluorescence images of endogenous AID in the presence of ectopically-expressed EV, AID, AIDR190X, or AIDcry in cytokine-stimulated CH12F3 cells. EV, empty vector control. An antibody against AID C terminus (185-198 aa) detected both endogenous and ectopically-expressed full-length AID. The nucleolus is indicated by co-nucleofected mCherry-FBL. The white dashed line depicts the shape of the nucleus based on Hoechst staining. Arrows indicate the location of puncta formed by endogenous AID. The images were taken by the N-SIM microscope and processed via N-SIM software. A middle slice of the images was shown. Scale bar, 5 µm.(B) Co-condensation of AID and AIDR190X in the nucleus of CH12F3 cells in the early G1 phase. Top: experimental layout. GFP-tagged wild-type AID (green) and mCherry-tagged AID variants (red) were co-nucleofected in Aicda-/- CH12F3 cells. The resulting cells were arrested with nocodazole for 12 hours after transfection. Six hours later, nocodazole was removed from the system for 1.5 hours before imaging. Bottom left: representative images showing subcellular localization of indicated AID variants. The white dashed line depicts the shape of the nucleus based on Hoechst staining. The white arrow indicates the location of the co-condensed puncta. Scale bar, 5 µm. Bottom right: plot profiles of the images. Cyto: cytoplasm, Nuc: nucleus.(C) Quantification of the relative fluorescence intensity of AID-GFP in the diluted phase of cells shown in (B). The fluorescence intensity of AID-GFP in the diluted nuclear phase was normalized by the total intensity from the whole cell. Data are shown as box plots. Values between lower quartile and upper quartile are represented by box ranges, a horizontal line within the box represents the median, and whisker extends from the minimum value to the maximum value. "+" indicates the mean level. Each dot indicates one cell (n = 25), and representative result from three biological replicates were shown. Unpaired two-tailed Student's t-test was performed. ****, p<0.0001.(D) Dynamics of trapping of wild-type AID in optoAIDR190X condensates. Top, representative fluorescence images at different time points. Dashed circles indicate the co-condensed puncta formation of AID-GFP. Scale bar, 5 µm. Bottom, a summary of 12 observed cells is shown as mean ±SD in a bar graph. Percentages of optoAIDR190X puncta with trapped wild-type AID are plotted for the second and third blue-light activations, and the colored dot indicates one cell.
Figure 4(B) The optoDroplet formation of indicated AID mutants along with light stimulation. Top, the procedure of optoDroplet assay is illustrated with indicated light stimulation (blue arrow) and image acquisition (black arrow) time points. Bottom, line plots show quantification of cells with optoDroplet formation as mean ± SD at each acquisition time point. The total acquired cell numbers of each genotype are indicated in parentheses. Significance assessment between AIDR190X and AIDR190X-4R was shown at each time point. Unpaired two-tailed Student's t-test was performed. ****, p<0.0001.(C) CSR levels of ectopically-expressed AID variants in AID-proficient CH12F3 cells. Left, representative flow cytometry plots of CSR to IgA. Co-expressed GFP indicates the infected cell fractions. Right, the CSR mean with SD of three biological replicates is shown in the bar plot. (D) CSR levels of ectopically-expressed AID variants in CSR-activated B cells. Left, representative flow cytometry plots of CSR to IgG1. Right, the bar plot shows the CSR mean with SD of four biological replicates. Data information: One-way ANOVA followed by Dunnett's multiple comparisons test was performed for (C) and (D). ***, p<0.001; **, p<0.01; *, p<0.05.
Figure 5(A) Left, representative images of MBP-GFP-AID in the presence of 10% PEG8000. Scale bar, 10 µm and 2 µm, respectively. Right, the schematic protein sequences.(B) Left, representative images of MBP-GFP-AIDcry+CTT or MBP-GFP-AIDcry in the presence 10% PEG8000 at the indicated protein concentrations. Scale bar, 10 µm. Right, sizes of MBP-GFP-AIDcry+CTT or MBP-GFP-AIDcry protein condensates are plotted as box plots with three technical replicates. The box represents values between the lower quartile and the upper quartile, a horizontal line within the box represents the median, and whisker extends from the minimum value to the maximum value. All points are listed and mean is indicated by "+". Unpaired two-tailed Student's t-test was performed. ****, p<0.0001.
Figure 6(A) AID deamination assay was performed in vitro. Left, a schematic diagram of deamination activity assay. Right, the deamination reaction with indicated protein combinations was processed and visualized. "+": 0.25 μM of indicated protein; "++": 0.5 μM of indicated protein; "-": not added.(B) CSR to IgA induced by AID variants in CH12F3 cells. Left, representative flow cytometry plots. Right, the CSR mean with SD of three biological replicates is shown in the bar plot. One-way ANOVA followed by Dunnett's multiple comparisons test was performed. ***, p<0.001; **, p<0.01.(C) Representative images of the co-condensation of MBP-mCherry-AIDcry and MBP-GFP-AID. The protein concentrations and molecular ratios are indicated. Scale bar, 10 µm.
Figure 1(C) Immunocytochemistry showing post-synaptic marker PSD-95 (red), pre-synaptic marker Synapsin-I (green), dendritic marker Map2 (blue) and co-localization of PSD-95 and Synapsin-I from dissociated Nedd4-2 WT or Nedd4-2 cKO hippocampal neurons at DIV 16. Representative secondary dendrites (left) and quantification of colocalized synaptic puncta number and area (right) (n = 36 for Nedd4-2 WT and Nedd4-2 cKO neurons) are shown. Scale bar: 5 µm.(F) A train of high frequency stimulation (HFS; 100 Hz for 1s) induced early-phase LTP (E-LTP) at Schaffer collateral synapses in Nedd4-2 WT (n = 7 slices from 6 mice) and Nedd4-2 cKO (n = 6 slices from 5 mice) mice. Representative fEPSP traces were recorded before and 60 min after LTP induction (Scale bars: 0.5 mV, 5 ms). Summary bar graphs showing the fEPSP slopes measured 50-60 min after a HFS at Schaffer collateral synapses was on the right. (G) Late-phase LTP (L-LTP) induced by four trains of HFS in Nedd4-2 WT slices (n = 7 slices from 7 mice) and Nedd4-2 cKO slices (n = 9 slices from 8 mice). Representative fEPSP traces were recorded before and 180 min after LTP induction (Scale bars: 0.5 mV, 5 ms). Summary bar graphs showing the fEPSP slopes measured 160-180 min after L-LTP induction at Schaffer collateral synapses was on the right.
Figure 2(B) Barnes maze test from Nedd4-2 WT (n = 8) or Nedd4-2 cKO (n = 8) mice (6-8 weeks old). Schematic representation of Barnes maze (top left). Mice were trained for 4 days with three training trials on each day to locate the escape box (black circle). Learning curve during 4 training days was shown by the escape latency and the number of errors before escaping (top right). Schematic representation of Barnes maze on probe trials (bottom left). Quadrant occupancy on probe trial at day5 and at day12 (bottom right) were assessed by the time spent in the target area (green quadrant).
Figure 3(B) Western blots of F-actin to G-actin ratio with or without cLTP induction from Nedd4-2 WT or Nedd4-2 cKO cultured neurons. Schematic representation of the experimental design for cLTP inductions (top left). Representative western blots (bottom left) and quantification of F-actin to G-actin from Nedd4-2 WT or Nedd4-2 cKO (right) cultures after cLTP induction and recovery in normal aCSF for 10 or 30 min before lysis (n = 11 and 8 for Nedd4-2 WT and Nedd4-2 cKO cultures, respectively). For quantification, data from cLTP induction were normalized to data from control (CTL) condition.
Figure 4(A) Western blots of Nedd4-2, total cofilin, phospho (p)-cofilin and GAPDH from Nedd4-2 WT or Nedd4-2 cKO forebrains at postnatal day 14. Representative western blots and quantification of total cofilin relative to GAPDH and p-cofilin relative to total cofilin (n = 6 for Nedd4-2 WT and Nedd4-2 cKO brains) were shown.(B) Immunocytochemistry of cofilin, p-cofilin and dendritic marker MAP2 from Nedd4-2 WT or Nedd4-2 cKO cultured hippocampal neurons at DIV 16. Representative dendrites of Nedd4-2 WT and Nedd4-2 cKO neurons and quantification of total cofilin relative to MAP2 and p-cofilin relative to total cofilin are shown (n = 25 and 26 for Nedd4-2 WT and Nedd4-2 cKO neurons, respectively). Scale bar: 5 µm.(C) Immunocytochemistry showing cofilin, p-cofilin, and dendritic marker MAP2 from Nedd4-2 WT or Nedd4-2 cKO cultured hippocampal neurons induced with or without cLTP at DIV 16. Representative dendrites and quantification from Nedd4-2 WT or Nedd4-2 cKO cultures are shown (n = 36-39 neurons). Scale bar: 5 µm. For quantification, data from cLTP induction were normalized to data from control (CTL) condition.
Figure 5(A) Immunocytochemistry showing post-synaptic marker PSD-95 (red), pre-synaptic marker Synapsin-I (green), dendritic marker Map2 (blue) and co-localization of PSD-95 and Synapsin-I from Nedd4-2 WT or Nedd4-2 cKO cultured hippocampal neurons at DIV 16 treated with TAT, TAT-S3, or TAT-pS3 peptide for 12 hrs (10 μM). Representative secondary dendrites of Nedd4-2 WT (top left) and Nedd4-2 cKO (bottom left) neurons are shown. Quantification of colocalized synaptic puncta number and synaptic puncta area for Nedd4-2 WT (top right) and Nedd4-2 cKO (bottom right) neurons is on the right (n = 32-36 neurons). Scale bar: 5 µm.(B) Patch-clamp recordings from Nedd4-2 WT or Nedd4-2 cKO hippocampal neurons treated with TAT, TAT-S3, or TAT-pS3 peptide for 12 hrs (10 μM) at DIV 14-17. Representative mEPSC traces from Nedd4-2 WT (top left) and Nedd4-2 cKO (bottom left) are shown. Quantification of mEPSC amplitude and frequency from Nedd4-2 WT (top right) and Nedd4-2 cKO (bottom right) neurons are shown (n = 22-24 neurons).
Figure 6(C) Barnes maze test after intraperitoneally injecting TAT (n = 8) or TAT-pS3 (n = 8) peptide in Nedd4-2 WT mice (top), or TAT (n = 9) or TAT-pS3 (n = 8) peptides in Nedd4-2 cKO mice (bottom). Learning curve during 4 training days of Barnes maze task showing the escape latency, number of errors before escaping, and the quadrant occupancy on probe trial at day 5 and at day 12 were assessed.
Figure 1(B) Immunoblot analysis of membrane fractions of HEK293 Flp-In cells stably overexpressing both mouse TREM2 and mouse DAP12 upon treatment with 4D9 antibody reveals increased levels of membrane-bound TREM2 similar to what can be achieved by ADAM protease inhibition using the GM6001 inhibitor. An isotype antibody was used as a negative control. Calnexin served as a loading control. Levels of membrane-bound TREM2 were quantified by MSD ELISA. Data represent the mean ± SEM (n=3). One-way ANOVA, Tukey's post hoc test; p (DMSO vs GM) = 0.0011; p (DMSO vs isotype) = 0.992; p (isotype vs 4D9) = 0.0005; n.s., not significant.(C) Immunoblot analysis of conditioned media from HEK293 Flp-In cells stably overexpressing both mouse TREM2 and mouse DAP12 upon treatment with 4D9 antibody reveals decreased levels of sTREM2 similar to what can be achieved by ADAM protease inhibition using the GM6001 inhibitor. An isotype antibody was used as a negative control. sAPPα served as a loading control. Note that heavy and light chains of the antibodies used for treatment are also detected and annotated. Levels of sTREM2 were quantified by MSD ELISA. Data represent the mean ± SEM (n=3). One-way ANOVA, Tukey's post hoc test; p (DMSO vs GM) < 0.0001; p (DMSO vs isotype) = 0.6372; p (isotype vs 4D9) < 0.0001; n.s., not significant.(D) 4D9 antibody selectively detects TREM2 on the cell surface of HEK293 Flp-In cells stably overexpressing mouse TREM2 and mouse DAP12. An anti-HA antibody was used as a positive control while empty vector transfected HEK293 Flp-In cells were used as a negative control. Scale bar= 10µm.(F) Sequence comparison of mouse TREM2 and human TREM2 shows substantial sequence conservation around the 4D9 epitope (upper panel). Immunoblot analysis demonstrates that antibody 4D9 is highly specific for mouse TREM2 and does not detect human TREM2 or mouse TREM1 (lower panel).(G) 4D9 binding to mouse TREM2 ECD is competed off by a stalk region peptide. A competition ELISA demonstrates that a dose titration of stalk peptide reduces binding of 4D9 to TREM2 ECD with an EC50 of 1.3uM. Data represent the mean ± SEM (n=3).(H) Surface plasmon resonance binding kinetics of increasing concentrations of 4D9 antibody to mouse TREM2 ectodomain evaluated by BIAcore, Kon = 5.9 x 105 M-1s-1, Koff = 4.0 x 10-5 s-1, KD = 68 pM. 4D9 binding to human TREM2 or mouse TREM1 was undetectable.
Figure 2(A) Flow cytometry dose response curve for cell binding of 4D9 mAb (EC50= 0.29nM), 4D9 Fab (EC50=0.17nM), and isotype to HEK cells stably overexpressing mouse TREM2. Data represent the mean ± SEM (n=2).(B) In vitro ADAM17 sheddase activity is blocked by 4D9-effectorless mAb and 4D9 Fab fragment but not an isotype control. Fluorescence polarization of FAM conjugated TREM2 stalk peptide was detected in the presence or absence of ADAM17 and 4D9 mAb, 4D9 Fab and isotype control. Data represent the mean ± SEM (n=6). One-way ANOVA, Tukey's post hoc test; p (4D9 Fab vs 4D9 mAb) = 0.8855; p (4D9 Fab vs uncleaved) < 0.0001; p (4D9 mAb vs uncleaved) < 0.0001; n.s., not significant.(C) ELISA-mediated quantification of sTREM2 in conditioned media from (D) AlphaLISA-mediated quantification of pSYK levels in HEK293 Flp-In cells stably overexpressing mouse TREM2 and mouse DAP12 treated with a dose titration of 4D9 mAb, 4D9 Fab or isotype for 5 minutes. Data represent the mean ± SEM (n=3).(E) AlphaLISA-mediated quantification of pSYK levels in HEK293 Flp-In cells stably overexpressing mouse TREM2 and mouse DAP12 or empty vector treated with 1mg/ml POPC/POPS liposomes and 20µg/ml 4D9 mAb, 4D9 Fab or isotype for 5 minutes. pSYK levels were also determined for cells treated with liposomes only. Data represent the mean ± SEM (n=3). Two-way ANOVA, Tukey's post hoc test (cell line effect: F1,16=365.7, p=<0.0001; treatment effect: F3,16=39.35, p<0.0001; cell line x treatment effect: F3,16=38.75, p<0.0001); p (no Ab vs isotype) = 0.6218; p (no Ab vs 4D9 mAb) < 0.0001; p (no Ab vs 4D9 Fab) = 0.7301; p (isotype vs 4D9 mAb) < 0.0001; p (isotype vs 4D9 Fab) > 0.9999; p (4D9 mAb vs 4D9 Fab) < 0.0001; n.s., not significant.
Figure 3(A) Flow cytometry detection of cell surface binding of 4D9 (blue) and isotype (green) to wild type and Trem2-/- mouse bone marrow derived macrophages. Representative histograms are shown as MFI (mean fluorescent intensity). Graphs represent the median signal intensity ± SEM (n=3). Student's t-test (two-tailed); Trem2+/+: p = 0.0005; Trem2-/-: p = 0.4435; n.s., not significant.(B) Immunoblot analysis of membrane fractions of bone marrow derived macrophages (BMDM) upon treatment with 4D9 antibody reveals increased levels of membrane-bound TREM2 relative to an isotype antibody. BMDM from TREM2 knockout mice were included to show the specificity of the anti-TREM2 antibody. Calnexin served as a loading control. Levels of membrane-bound TREM2 were quantified by MSD ELISA. TREM2 antibody clone 5F4 was used for detection. Data represent the mean ± SEM (n=5-6). Unpaired t-test (two-tailed) with Welch's correction; p<0.0001. No gender-specific differences could be observed.(C) Immunoblot analysis of sTREM2 in conditioned media from BMDM upon treatment with 4D9 and isotype antibodies. BMDM from TREM2 knockout mice were included to show the specificity of the anti-TREM2 antibody. Soluble APP served as a loading control. Note that heavy and light chains of the antibodies used for treatment are also detected and annotated as follows: Ab hc= antibody heavy chain; Ab lc= antibody light chain. Levels of sTREM2 were quantified by MSD ELISA. TREM2 antibody clone 5F4 was used for detection. Data represent the mean ± SEM (n=6). Unpaired t-test (two-tailed) with Welch's correction; p<0.0001. No gender-specific differences could be observed.(D) Wildtype, Trem2+/-, and Trem2-/- BMDMs were plated in low concentration of M-CSF on 4D9 or isotype coated wells for 5 days and cellular ATP levels were measured by luminescence detection to indicate cell viability. 4D9 and isotype data for each genotype represent the mean ± SEM (n=2 and n=1, respectively).