EMBO/SourceData huggingface dataset:
Figure 4Serum anti-Insulin-immunoglobulin titers of mice immunized with InsA-peptide (red: 0:1, n=10 and green: 100:1, n=5) and control-immunization (CI: CpG only, grey, n=3) measured by ELISA at indicated days (coating: Insulin). Dots represent individual mice. Mean ± SD, statistical significance was calculated by using Kruskal-Wallis test, *P < 0.05, ***P < 0.001.Western blot analysis of insulin-specific serum IgG derived from InsA-peptide immunized mice. Top panel (green): 100:1 serum, lower panel (red): 0:1 serum (sInsA:cInsA). Serum of mice was used as primary antibody and detection was done with anti-mouse-IgG-HRP. Black filled arrow: Proinsulin (12 kD), Black non-filled arrow: Insulin (6 kD), β-actin (42 kD, loading control). Representative of two independent experiments.Blood glucose levels of InsA-peptide immunized (red: 0:1, n=5 for E and n=10 for F; green: 100:1, n=5 and n=4 for F, d30, d32) and CI (grey, n=5 for E and n=10 for F) mice were assessed at indicated days. Dots represent individual mice. Mean ± SD, statistical significance was calculated by using Kruskal-Wallis test (E) and repeated measure ANOVA test (F), *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.Urine glucose levels of InsA peptide immunized (red: n=10 for d28, d32 and n=8 for d30; green: n=5 for d28, n=4 for d30, n=3 for d32) and CI (grey, n=3) mice were monitored at indicated days post immunization. Dots represent individual mice. For 100:1: representative data are shown for two independent experiments with total n=10. Mean ± SD, statistical significance was calculated by using repeated measure ANOVA test, ***P < 0.001.
Figure 5(C, F) Urine glucose levels of InsA peptide immunized (n=3) and CI (n=3) mice were monitored at indicated days post immunization. Dots represent individual mice. Mean ± SD, statistical significance was calculated by using repeated measure ANOVA test, *P < 0.05. (D, E) Serum anti-Insulin-immunoglobulin titers of mice immunized with InsA-peptide (day 59, day 78: n=3, day 49: n=7) and control-immunization (CI: CpG only, n=3) measured by ELISA at indicated days (coating: Insulin). Dots represent individual mice. Mean ± SD, statistical significance was calculated by using Mann-Whitney-U test (D) and repeated measure ANOVA test (E). *P < 0.05, **P < 0.01.
Figure 6Anti-Insulin affinity of PR-IgM (blue), primary IgM (red) and isotype control (black) measured by bio-layer interferometry. IgM binding to insulin was acquired in pm and used to calculate the dissociation constant shown in the graph (Kd = 1/Ka). Graph is showing antigen-antibody association phase. Data are representative for three independent experiments.Blood glucose levels of intravenously injected mice with purified IgM from control immunization (CI, n=5), complex InsA peptide (cInsA) immunization day 7 (total IgM d7, n=4) and day 85 (total IgM d85, n=5). Mean ± SD, statistical significance was calculated by using repeated measure ANOVA test showing comparison of red to black line, **P < 0.01, ***P < 0.001, ****P < 0.0001.
Figure 7Anti-nuclear-IgM (ANA) of control-immunized (CI, n=3) and complex InsA peptide (cInsA) immunized mice on day 7 (n=3) and day 85 (n=3) analyzed by indirect immunofluorescence. We used (E) total serum (dilutions: 1:20) or (G) Insulin-specific IgM (concentration: 500 ng/mL) purified from serum at indicated days on commercial HEp-2 slides. Scale bar: 10 µm. Green fluorescence indicates IgM bound to nuclear structures. Data are representative for three independent experiments with isotype control: n=3, day 7: n=3, day 85: n=3.Coomassie stained SDS-page showing primary (cInsA d7) and memory (cInsA d85) Insulin-specific purified IgM pre-incubated with Insulin and calf thymus dsDNA. Samples were loaded onto the gel after size exclusion with a cut-off at 10.000 kD (fractions referring to >/< 104 kD). IgM heavy chain (HC): 69 kD, IgM light chain (LC): 25 kD, J-chain: 15 kD. Data shown are representative of three independent experiments.
Figure 2Sashimi plots of representative SRSF3-dependent exons. C2C12 cells were treated with control siRNA (siCont), Srsf3 siRNA (siSrsf3), Hnrnpk siRNA (siHnrnpk), or both Srsf3 and Hnrnpk siRNAs (siSrsf3+siHnrnpk), and RNA-seq was performed. Lines indicate junction-spanning reads. Gene structures are shown below the Sashimi plots.
Figure 3Volcano plot showing fold changes versus P-values of the normalized MASCOT scores (see Materials and Methods) of identified proteins between 3XFLAG-SRSF3-IP and Cont-IP. Each experiment was triplicated. The members of the representative families of splicing factors are highlighted by colors (right upper box).   Volcano plot showing fold changes versus P-values of the normalized MASCOT scores of identified proteins between 3XFLAG-HNRNPK-IP and Cont-IP. Each experiment was triplicated. The members of the representative families of splicing factors are highlighted by colors (right upper box).
Figure 4mRNA expression levels of seven CPSF factors in C2C12 cells treated with the indicated siRNA normalized for those treated with the control siRNA. **p < 0.01 by CuffDiff (Trapnell et all., 2010).Western blots showing protein expression levels of CPSF6 and β-actin (ACTB). Whole cell lysates were harvested 42 h after siRNA transfection.
Figure 6SRSF3-responsive alternative 3′ ends of the Med1 gene. (Top panel) Disorder analysis for MED1 using PONDR VL-XT (deep blue) and IUPred2 (light blue). The scores in the ordinate indicate disordered tendencies between 0 and 1 (a score of more than 0.5 indicates disordered). (Middle panel) Protein and gene structures of MED1. The protein structure was segmented into individual exonic regions. The SRSF3-responsive last exon is indicated in pink. (Bottom panel) Sashimi plots of RNA-seqs from Srsf3- and/or Hnrnpk-silenced cells.Immunofluorescence images of MED1 in C2C12 cells treated with siCont (C), siSrsf3 (S), siHnrnpk (K), or siSrsf3+siHnrnpk (S+K). A white dotted contour outlines the nucleus. Box plots (right) show quantification of nuclear (NUC) and cytoplasmic (CYT) localization of MED1. The average intensity of one nucleus or a cytoplasmic segment is individually plotted.The intrinsically disordered region (IDR) in MED4. Disorder analysis, protein and gene structures, and Sashimi plots are shown in (B). Splicing of these genes was not affected by the siRNA treatment.Immunofluorescence images of MED4 in C2C12 cells treated with the indicated siRNAs. Box plots show quantification of nuclear localization of MED4. Each dot represents one nucleus.Immunofluorescence images of MED1 and MED4 in C2C12 cells The arrows denote representative puncta, including both MED1 and MED4.The number of MED1 puncta (left) and MED4 puncta (right) per nucleus in cells treated with the indicated siRNA.MED1 signals on MED4 puncta normalized to nuclear MED1 signals. MED1 signal intensity on each MED4 punctum was individually plotted.
Figure 1 (B) Expression of S protein on the plasma membrane of Jurkat-S cells assessed by surface biotinylation and followed by immunoprecipitation with anti-T2A, SDS-PAGE under reducing conditions and western blot with streptavidin-peroxidase. Biotinylation of the parental Jurkat cells was carried out in parallel as a negative control. The arrow indicates the position of the reduced S protein. (C) Expression of the S protein in native form was assessed by surface biotinylation of Jurkat-S and Jurkat cells followed by immunoprecipitation with anti-T2A followed by SDS-PAGE under non-denaturing conditions (i.e. without reducing agents and without boiling). The nitrocellulose membrane was blotted with streptavidin-peroxidase. Arrows point at different oligomerization forms of the S protein.  (D) Formation of syncytia between the CTFR-labelled ACE2+ human cell line and the CFSE-labelled Jurkat-S cells was measured by flow cytometry by analyzing the percentage of cells that become double positive for CTFR and CFSE markers. The Bar plot to the right shows the effect of different doses of HepG2 cells on the formation of syncytia with a fixed number of Jurkat. Parental Jurkat cells (not expressing S protein) are considered negative controls. Data represent the mean±SD of triplicated datasets.  (E) Formation of syncytia between the CTFR-labelled ACE2+ human cell line and the CFSE-labelled Jurkat-S cells, in an experiment as in D, was confirmed by confocal microscopy after sorting cells double positive for CTFR and CFSE. Nuclei were identified by DAPI staining. Red arrowhead in the DAPI image indicates a nucleus of Hep-G2 origin; the green arrowhead the nucleus of Jurkat-S origin.  (F) Overlay plot of Jurkat-S cells that were incubated with anti-EGFR mAb conjugated to Bv421 and serum from either donor #15 or from a pre-COVID-19 donor and followed by a secondary anti-human IgG1 antibody conjugated to PE.
Figure 2 (A) Overlay histograms of Jurkat-S staining with different human sera diluted 1:50. A pre-COVID19 serum sample is taken as negative control (grey histogram).  (B) Bar plots of flow cytometry data generated with Jurkat-S cells and the panel of serum samples of Table EV1 classified according to their result in the indicated commercial tests: green, positive for the test; orange, weak or unclear; magenta, negative samples. Flow cytometry data is expressed as the ratio between the MFI of the antibody anti-S and the MFI for EGFR. Negative values for the flow cytometry test are those with a S/EGFR MFI ratio lower than 0.5. This ratio was set in order to fit most of the data negative for the other serological tests (pink triangles) under that threshold.Data represent the mean±s.e.m. All datapoints are shown.
Figure 3 (A) Box and whiskers plot of MFI and absorbance data in human sera according to their clinical classification of COVID-19 symptoms. Clinical classification was done according to the following parameters: Asymptomatic, no symptoms; Mild, 3 or more of the following symptoms: non-productive cough, hyperthermia, headache, odynophagia, dyspnea, asthenia , myalgia, ageusia, anosmia, cutaneous involvement; Moderate, 3 or more of the above symptoms plus gastrointestinal symptoms, or more than 3 of the above for 7 or more days; Moderate-Severe, 3 or more of the above symptoms plus pneumonia. Box and whiskers are shown to represent the minimum and maximum values as well as the median. All datapoints are shown.  (B) Comparison of MFI versus absorbance data generated by flow cytometry and ELISA for all human sera. A lineal regression curve was adjusted, with a 95% confidence interval, to all data with the R2 values indicated in the plots. #5Selected samples of outliers (#4, #5, #8, #31, #46, #48, #49 and #58) as well as samples close to a diagonal (#36, #52 and #15) are indicated.  (C) Titration of selected human sera by ELISA using the S1 protein and by flow cytometry with Jurkat-S cells. Samples with antibodies detected by flow cytometry and not by ELISA are indicated (#8, #46, #48, #49). Data represent the mean±SD of duplicates. An unpaired two-tailed t-test was carried out to compare the results of 1:50, 1:150 and 1:450 dilutions of sera #8, #46, #48 and #49 by FC to the pre-COVID-1 sample as a negative control. *, p<0.05; **, p<0.005; ***, p<0.0005.
Figure 4 (B) Validation of the neutralization method was carried out with cell HEK-293T cell culture supernatants containing lentiviral particles pseudotyped with either the S protein or with the VSV G protein. The supernatants were mixed with sera from donor #66 at the indicated dilutions or from a pre-COVID sample as a control before addition onto HEK-293T-ACE2+ cell cultures. No serum, refers to a control containing no human sera. Data represent the mean±SD of triplicates.  (C) The presence of neutralizing antibodies in sera from donors #46 and #48, found negative by ELISA and positive by flow cytometry (Fig. 3C) was demonstrated as in panel B. Data represent the mean±SD of triplicates. *, p<0.05; **, p<0.005; ****, p<0.00005 (Paired two-tailed t-test comparing all serum dilutions to the pre-COVID sample).  (D) Bar plot showing the S/EGFR MFI ratio determined by flow cytometry analysis with Jurkat-S of serum samples from 30 sanitary personnel repeatedly tested as PCR negative for SARS-CoV-2 at the Ramón y Cajal Hospital of Madrid. A negative result is considered for a ratio lower than 0.5. Two clear cases of sera positive for anti-S IgG1 are indicated (RyC52 and RyC65). A borderline sample just above the threshold line (RyC58) is also indicated. Data show the mean±s.e.m. All datapoints are shown.  (F) Plot of the S/EGFR MFI ratio for the 30 RyC samples versus a Score generated according to the slope of S/EGFR and shape (see Materials and Methods and Fig. EV1). The green line indicates the threshold point (0.024) for the Score above which a serum is considered positive.   (G) The presence of neutralizing antibodies in sera from donors RyC46, RyC52, RyC56 and RyC58 diluted 1/15 was demonstrated as in panel B. Data represent the mean±SD of triplicates. *, p<0.05; **, p<0.005; ****, p<0.00005 (Unpaired two-tailed t-test comparing each serum to the No serum sample)
Figure 5 (A) A total of 52 serum samples from Hospital Universitario La Princesa (HUP) and 52 samples of pre-COVID donors stored at the CBMSO were tested by the flow cytometry method and classified according to the S/EGFR-based Score. Of the 52 HUP samples, a total of 40 were from donors testing positive by PCR and by an ELISA test, 6 were from donors testing negative by PCR but positive by ELISA, 1 from an individual testing negative by ELISA and positive by PCR, and 5 were not tested by PCR. Box and whiskers are shown to represent the minimum and maximum values as well as the median. All datapoints are shown. The broken line indicates the threshold for a Score value of 0.024.  C) Four HUP serum samples giving discrepant results by flow cytometry method were tested in the neutralization assay of pseudotyped lentivirus (Fig. 4A). Data represent the mean±SD of duplicates. *, p<0.05; **, p<0.005; ****, p<0.00005; (Paired two-tailed t-test comparing all serum dilutions to the pre-COVID sample)
Figure 6 (A) A collection of serum samples from volunteers working at the CBMSO were taken in the months of June and October 2020 and tested by flow cytometry using Jurkat-S cells at the indicated dilutions. Flow cytometry data are shown as the S/EGFR MFI ratio. Red arrows indicate a loss in titer of antibodies between June and October whereas blue arrows indicate an increase in antibody titer.
Figure 7 (B) A neutralization assay with S protein-pseudotyped lentivirus was carried out to resolve the discrepancies. Data represent the mean±SD of duplicates. *, p<0.05; **, p<0.005; ***, p<0.0005; *****, p<0.000005 (Paired two-tailed t-test comparing all serum dilutions to the pre-COVID sample).  (C) Classification of the CBMSO cohort according to the Score generated from S/EGFR data. The Broken line indicates the 0.024 threshold above which samples are considered positive.
Figure 1(D) Stretching of the PDMS sandwich concomitantly stretches the wing disc inside the microchannel (top-down view); wing disc resting on a stretching device (anchor) and 10 min after stretch; M=microchannel.(E) zipper RNAi clones (zip iR, in red) in Arm::GFP expressing anchored and stretched third instar wing disc; lower panel shows color coded cell aspect ratio in anchored and stretched discs (bright colors indicate high elongation); zip RNAi clone is outlined in white.(F) Box plot showing distribution of cell aspect ratio for control (wild-type) and zipper RNAi cells in anchored and stretched (20 min) wing disc; median represented by horizontal line, 75th and 25th centiles are represented by top and bottom of the boxes respectively; n=8 wing discs.(G) Color-coded aspect ratio in control and zip RNAi cells (zip RNAi clone outlined in white) subjected to anchoring, stretching (20 min) and relaxation (10 min, post stretch).(H) Box plot showing distribution of cell aspect ratio in anchored, stretched (20 min) and relaxed (10 min) wing disc for control (wild-type) and zipper RNAi cells; median represented by horizontal line; 75th and 25th centiles are represented by top and bottom of the boxes respectively, n=3 wing discs.(I) zip-RNAi clone in Arm::GFP wing disc at the beginning (5 min) and at the end (40 min) of stretching experiment. Yellow and red arrows indicate the control and zip RNAi cells respectively.(J) Change of zip-RNAi aspect ratio (a.r.) relative to change in control cells aspect ratio (a.r.) in the course of stretch, blue line shows fitted regression; dotted line represents 95% confidence bounds of the best fit line; n=3 wing discs.
Figure 2(A) Wing disc expressing E-cad::GFP and Sqh::mCherry prior to stretch (anchor) and after stretch (15 min). (A"), Insets of discs shown in (A). (B) Schematics demonstrating change in Sqh concentration before and after stretch on vertical (V) and horizontal (H) junctions(C) Quantification of mean fluorescent intensity of E-cad::GFP and Sqh::mCherry on horizontal (H) junctions relative to the intensity on vertical (V) junctions (referred to as "polarity") prior to and after 15 min stretch. The detailed rationale of intensity determination is described in Fig. S3 and Experimental Procedures.(D-E), Quantification of E-cad::GFP (D) and Sqh::mCherry (E) concentration (i.e. mean intensity per junctional unit area) prior and after stretch on both horizontal and vertical junctions normalized to starting concentration on unstretched (anchored) vertical junctions.(F) Quantification of total amount of Sqh::mCherry and E-cad::GFP fluorescence on vertical and horizontal junctions in anchored and stretched discs.(G) Tissue expressing E-cad::GFP and Sqh::mCherry subjected to increasing levels of stretch.(H) Quantification of Sqh::mCherry polarity (as in c) of experiment described in (G). The level of stretch is measured as a change in tissue strain (deformation relative to unstretched tissue).(I-K) Sqh::mCherry polarity emergence as a function of cell aspect ratio change (I), stress (J), stress applied on average cell area of 10 μm2 (K). Yellow asterisks indicate equivalent regions in the tissue. N=8 wing discs (A- F), N=3 wing discs (G-K);
Figure 3(A) Short (15 min) stretch and relaxation (10 min) of E-cad::GFP and Sqh::mCherry expressing discs.(B) Quantification of Sqh::mCherry polarity, E-cad::GFP polarity and aspect ratio change of experiment described in (A); schematics below the graph illustrates quantified changes in cell aspect ratio (yellow) and Sqh polarity (red). Statistical test compares Sqh polarity between anchored and stretched or stretched and relaxed disc.(C) Long (200 min) stretch and relaxation (10 min) of E-cad::GFP and Sqh::mCherry expressing discs.(D) Quantification of Sqh::mCherry polarity, E-cad::GFP polarity and aspect ratio change of experiment described in (C); schematics below the graph illustrates quantified changes in aspect ratio (yellow) and Sqh polarity (red).
Figure 4(A) Overview of the E-cad::GFP disc prior to (anchor) and after compression.(B) E-cad::GFP and Sqh::mCherry localization in anchored and compressed wing disc.(C) Laser cuts (perpendicular to the line of stretch) across circa 10 cells in E- cad::GFP expressing wing disc tissue subjected to anchoring, short (<20 min) stretching and short (<20 min) compression. Plot shows increase in distance between recoiling short axis [μm] of the fitted ellipse (see Fig. S5A for details) against time [sec.]; data is plotted as mean ± S.E.M, n= 7-10 discs/condition.(D) Activated Myosin (anti-phosphorylated-Sqh; in red) and anti-E-cad (green) staining in compressed discs. (D") Close up of compression experiment described in (D); yellow arrow points towards an example of polarized phosphorylated-Sqh cable in compressed discs.
Figure 5(A) Laser cuts (perpendicular to the line of stretch) across circa 10 cells in E- cad::GFP expressing wing disc tissue subjected to anchoring, short (<20 min) and long (>120 min) stretching and stretch retraction (tissue forced back to the original, pre-stretch shape.(C) An overlay of a junction prior to (red) and 15.44 sec. after ablation (green).(E) Laser cuts (perpendicular or parallel to the line of stretch) across circa 10 cells in E-cad::GFP expressing wing disc tissue subjected to anchoring or short stretching (< 30 min)..(H) An overlay of anchored and stretched discs prior to ablation (red) and 15.44 seconds post ablation (green). Inset zooms in on the area next to ablation site (marked with yellow asterisk).
Figure 6(A) RokK116a::Venus localization in anchored, stretched, relaxed third instar imaginal discs.discs. (B) Drok2 mitotic clones (RFP-) in Sqh::GFP third instar imaginal disc. Inset demonstrates Sqh::GFP polarity inside Drok2 clone.(C) Sqh::GFP, enGal4>UAS-rok RNAi, UAS-Act5CRFP discs subjected to stretching; inset demonstrates Sqh::GFP polarity in rok RNAi cells (marked by red.(D) zip RNAi clones (labeled as zip iR, indicated in red) in stretched third instar RokK116a::Venus discs.
Figure 7(A) Discs expressing Sqh::GFP and enGal4>UAS-dia RNAi, UAS-Act5c-RFP that were stretched; UAS-Act5C::RFP marks dia iR (posterior side) in red. (A") Insets comparing Sqh::GFP polarity in stretchedenGal4>dia iR, UAS- Act5c-RFP discs; panel 1 refers to anterior (ctrl) side; panel 2 refers to posterior (dia iR) side. (B) Tissue marked with E-cad::GFP and Sqh::mCherry, expressing dia-RNAi (dia iR) with hhGal4 driver and subjected to stretching. Dotted line indicates anterior-posterior (A-P) compartment boundary. (B") Inset demonstrates lack of Sqh::GFP polarity in dia-RNAi cells. (C-D), Quantification of E-cad::GFP polarity (C) and Sqh::mCherry polarity (D) in experiment described in (B); polarity is measured as mean fluorescent intensity on horizontal junctions relative to vertical junctions (see Experimental Procedures for details); n=4 wing discs.(E) Stretched discs expressing Sqh::GFP and enGal4>UAS-cofilin (upper panel) or UAS-AIP1 (lower panel) RNAi and UAS-Act5c-RFP (marks posterior side in red). (E"), Insets comparing Sqh::GFP polarity in stretched discs described in (E); panel 1 refers to anterior (ctrl) side; panel 2 refers to posterior (dia iR) side.(F) Sqh::GFP polarity in enGal4> dia iR, UAS-Act5C::RFP discs labeled with Phalloidin-647; Inset (Phall-647) zooms in on cell shape in anterior and posterior disc compartments.(G) Discs expressing nubGal4 and Cd8::GFP (control) or dia iR (KK) labeled with DAPI; ellipse is fitted into the pouch region (red dotted line) and aspect ratio determined as long ellipse axis (b) divided by short ellipse axis (a) (white lines).(H) Box plot showing distribution of wing disc pouch aspect ratios in conditions described in (G), n=19 (ctrl) and 16 (dia iR) wing pouches; horizontal line indicates median.
Figure 1(C) Co-immunoprecipitation using BmN4 cells transfected with the Flag-tagged DEAD-box helicases identified by shotgun proteomics. The Flag-tagged proteins and Ago3 were detected by western blotting. Full-length Flag-tagged proteins are indicated with red asterisks. h.c.: heavy chain.(F, G) Analysis of Siwi-piRNA and Ago3-piRNA levels in Siwi and Ago3 complexes with DDX43, respectively. The WB (western blotting) and NB (northern blotting) signals represent the PIWI protein and piRNA levels, respectively (see also Figs EV1A and EV1B). The relative ratios of piRISC were calculated based on the signal intensities of the PIWI proteins and piRNAs.
Figure 2(B) Immunoprecipitation and western blotting showing that DDX43 associated with Vret and Ago3.(C, D) Immunoprecipitation of endogenous Siwi, DDX43, and Vret bound with Ago3 from DDX43-depleted (C) or Vret-depleted (D) cells. The factors were detected by western blotting. Ago3 interacts with Vret and DDX43 independently of the other.