EMBO/soda-nel huggingface dataset:
The TRAPP complex mediates secretion arrest induced by stress granule assembly (2019)
Figure 1

Figure 1.

The TRAPP complex is recruited to stress granules

A. Localization of TRAPP complex components after sodium arsenite (SA) treatment in HeLa cells treated with 300 µM SA for 30 min. Fluorescence microscopy of fixed cells using antibodies against TRAPPC2 and eIF3 (to label SGs) at steady state and after SA treatment (top two rows). Other panels show localization of GFP-TRAPPC3 and endogenous TRAPPC1 to eIF3-labeled SGs and of endogenous TRAPPC9 and TRAPPC8 to G3BP-labeled SGs. DAPI (blue). Scale bar, 10 µm.

B. Representative images of a time course analysis of TRAPPC2 redistribution to SGs. Cells were treated as in (A). The graph (B') shows quantification of TRAPPC2 localization at SGs over time as the ratio between TRAPPC2 (mean fluorescence intensity) in SG puncta and cytosolic TRAPPC2. Mean ± s.e.m. n = 50 cells per experiment, N = 3. Scale bar, 10 µm.

C. Analysis of TRAPPC2 (green), TRAPPC8 (blue) and TRAPPC9 (orange) localization at SGs upon TRAPPC2, TRAPPC4 TRAPPC8 and TRAPPC9 depletion. Mean ± s.e.m. n>100. *p<0.05; ns: not significant, One-way ANOVA with Dunnett's multiple comparison test.

D. Schematic representation of MS/MS analysis of TRAPPC2 interactors. In addition to the TRAPP components and known TRAPPC2 interactors, 53 RNA binding proteins known to associate with SGs were co-IP with TRAPPC2. Proteins that associate with TRAPPC2 only upon SA-treatment are highlighted in red.

E. Analysis of TRAPPC2 localization at SGs upon CLIC1, CRYAB and ENO1 depletion. Mean ± s.e.m. n>100. ****p<0.0001; ns: not significant, One-way ANOVA with Dunnett's multiple comparison test.
The TRAPP complex mediates secretion arrest induced by stress granule assembly (2019)
Figure 2

Figure 2.

TRAPPC2 is required for Sec23/24 relocalization to SGs

A. HeLa cells, untreated or treated with SA, were fixed and visualized by fluorescence microscopy using anti-Sec24C Ab, anti-eIF3 Ab, and DAPI (blue).

B. Quantification of Sec24C redistribution to SGs over time after SA treatment (the ratio between Sec24C (mean fluorescence intensity) in SG puncta and cytosolic Sec24C). Mean ± s.e.m. n = 50 cells per experiment, N = 3.

C. Quantification of residual Sec24C in ERES after SA treatment. The data are expressed as percentage of steady state values (CTRL). Mean ± s.e.m. n = 100 cells per experiment, N = 3.

D. Representative images of TRAPPC2 localization in Sec23AB-KD and Sec24ABCD-KD cells treated with SA. Cells were fixed and visualized by fluorescence microscopy using anti-TRAPPC2 Ab, anti-G3BP Ab (to label SGs) and DAPI (blue).

E. Quantification of TRAPPC2 redistribution to SGs after KD of the indicated Sec23 and Sec24 combinations, calculated as the ratio between TRAPPC2 (mean intensity) in SG puncta and cytosolic TRAPPC2 and expressed as % of CTRL. Mean ± s.e.m., n = 40-60 cells per experiment, N = 3. ns: not significant, One-way ANOVA with Dunnett's multiple comparison test.

F. Representative images of Sec24C localization at SGs (stained for G3BP) in TRAPPC3-KD and TRAPPC2-KD cells treated with SA. Depletion of the entire TRAPP complex (via TRAPPC3 depletion) or of only TRAPPC2 reduces Sec24C recruitment. Graph, quantification of Sec24C at SGs, calculated as in (E). Mean ± s.e.m., n = 40-60 cells per experiment, N = 3. ****p< 0.0001, One-way ANOVA with Dunnett's multiple comparison test.

G. Representative images of Sec24C localization at SGs (stained for G3BP) in TRAPPC2-KO cells treated with SA.

Data information: (A, D, F, G) Scale bars, 10 µm.
The TRAPP complex mediates secretion arrest induced by stress granule assembly (2019)
Figure 3

Figure 3.

Comparison and relationships between the ERES-associated and the SG-associated pools of TRAPP and COPII

A. TRAPP and COPII associate more stably with SGs than with ERES. The membrane­­ association of Sec24C was evaluated in non-permeabilized or permeabilized cells with or without SA treatment, as indicated. G3BP was used as an SG marker. Left panel insets, G3BP staining in non-permeabilized cells. Dashed white lines show the outline of permeabilized SA-untreated cells. Blue, DAPI.

B. Stabilizing TRAPP and COPII at the ERES prevents their relocalization to SGs. HeLa cells overexpressing GFP-Sar1H79G were treated with SA and immunostained for Sec24C, TRAPPC2, and eIF3, as indicated. Blue, DAPI. Graphs show quantification of Sec24C or TRAPPC2 at SGs in GFP-Sar1H79G-expressing cells. Data are the ratio between Sec24C or TRAPPC2 mean intensity in SG puncta and Sec24C or TRAPPC2 mean intensity at ERES, expressed as a percentage of the non-transfected (NT) cells. Mean ± s.e.m. n = 60-70, three independent experiments. ****p<0.0001, Student's unpaired two-tailed t-test.

C. Effect of Sec31A depletion on TRAPPC2 recruitment to SGs. Cells were mock-treated or KD for Sec31, treated with SA, and then immunostained for TRAPPC2 and eIF3 as indicated. Graphs, quantification of TRAPPC2 at ERES and SGs after SA treatment. Mean ± s.e.m., one representative experiment; n=60-80. ** p<0.001, ****p<0.0001, Student's unpaired two-tailed t-test.

D. Effect of Sec31A depletion on Sec24C recruitment to SGs. Cells were mock-treated or KD for Sec31 and then immunostained for Sec24C and cTAGE5 (to stain ERES, top panels) and for eIF3 (bottom panels). Insets show eIF3. Graphs, quantification of Sec24C at ERES and in SGs after SA treatment. n=80. ****p<0.0001, Student's unpaired two-tailed t-test.

Data information; (A-D) Scale bars, 10 µm.
The TRAPP complex mediates secretion arrest induced by stress granule assembly (2019)
Figure 5

Figure 5.

CDK1/2 modulate the COPII cycle at ERES

A. Immunofluorescence images of Sec24C and TRAPPC2 in vehicle-treated and SNS-032-treated (1 µM, 3 h) cells. Graphs show the quantification of Sec24C and TRAPPC2 at ERES (mean intensity) normalized in SNS-032-treated cells relative to vehicle-treated cells (set as 100%). Mean ± s.e.m. of three independent experiments. **p<0.05, ****p<0.0001, Student's unpaired two-tailed t-test.

B. HeLa cells were treated with Dinaciclib (1 µM, 3 h) and permeabilized or not with digitonin as described in Materials and Methods. A GM130 antibody was added to the buffer of living cells to monitor permeabilization efficiency. Upper panels, non-permeabilized (NP) control cells; middle panels, permeabilized control cells; lower panels, permeabilized Dinaciclib-treated cells.

C. Quantification of Sec24C membrane association after CDK inhibitor treatment. Digitonin-permeabilized cells treated with vehicle (CTRL) or the indicated CDK inhibitor (1 µM, 3 h) were immunostained for Sec24C. The mean intensity of Sec24C in the perinuclear area normalized for the cytosolic Sec24C signal in drug-treated cells is expressed as fold change compared to the control; n= 60-80; mean ± s.e.m. of three independent experiments ****p<0.0001, One-way ANOVA with Dunnett's multiple comparison test.

D. HeLa cells transfected with HA-hnRNPK were left untreated (Steady state) or treated with SA (300µM, 30 min) or SA+Dinaciclib (10 µM, 150 min) and then immunostained with anti-HA and anti-G3BP antibodies.

E. TRAPPC2 interacts with hnRNPK. (Top) SDS-PAGE and Western blot analysis of endogenous hnRNPK after immunoprecipitation with an anti-TRAPPC2 Ab or IgG, and (bottom) after immunoprecipitation with an anti-HA Ab from cells transfected (+) or not (-) with hnRNPK-HA detected with the indicated antibodies.

F. Mock or hnRNPK KD cells treated with SA were immunostained for TRAPPC2 and eIF3.

G. Mock or hnRNPK KD cells treated with SA were immunostained for Sec24C and G3BP.

H. Graphs show quantification of TRAPPC2 and Sec24C redistribution to SGs in mock treated (CTRL) and hnRNPK KD cells. n>100, N=3 mean ± s.d. ***p<0.001.****p<0.0001, Student's unpaired two-tailed t-test.

Data information: (A, B, D, F, G) Scale bars, 10 µm.
The TRAPP complex mediates secretion arrest induced by stress granule assembly (2019)
Figure 6

Figure 6.

TRAPP and Sec23/24 migration to SGs depends on the proliferation state of cells

A. HeLa cells were starved for 8 h with HBSS and subsequently exposed to SA (30 min, 300 µM), and immunostained for Sec24C or TRAPPC2 and eIF3. Scale bar 10 µm.

B. Analysis of the proliferation status of the cells after 8 h starvation in HBSS. Top, representative images of starved and non-starved (CTRL) cells using EdU incorporation (see Materials and Methods). Scale bar 100 µm. Bottom, quantification of EdU incorporation in starved cells as a percentage of incorporation in control fed cells, N=3, mean ± s.d.

C. HeLa cells were seeded at different confluency, treated with SA and stained for Sec24C and G3BP as an SG marker. Scale bar, 10 µm. Flow cytometry (FACS) analysis (right panels) was performed to evaluate the distribution of cell cycle phases in HeLa cell populations seeded at different confluency. The graph shows quantification of Sec24C mean intensity in SG puncta (normalized for the cytosolic Sec24C) at the indicated cell confluency. Mean ± s.e.m. of a representative experiment out of 5 biological replicates. n= 50-80. ns: not significant; ****p<0.0001, One-way ANOVA with Dunnett's multiple comparison test.

D. Differentiation of podocytes. Western blot of growing and differentiated podocytes. Synaptopodin (SYNPO) was used as a differentiation marker, GAPDH as a loading control.

E. Growing and differentiated podocytes were treated with SA (300 µM, 30 min) and stained for TRAPPC2 or Sec24C and eIF3. Scale bar, 10 µm. The graphs show quantification of TRAPPC2 and Sec24C (mean intensity) in SGs. Mean ± s.e.m. of three independents experiments. ****p<0.0001, Student's unpaired two-tailed t-test.

F. Western blot analysis of total (RB) and phosphorylated (p-RB) retinoblastoma in growing (non-differentiated) versus differentiated podocytes. ß-actin was used as loading control.

G. CDK kinase activity in growing and differentiated podocytes. Western blot using a specific antibody recognizing phosphoSer-CDK substrates was used on total cell lysates.
The TRAPP complex mediates secretion arrest induced by stress granule assembly (2019)
Figure 7

Figure 7.

The TRAPP complex controls SG composition and function

A. SG area (see Materials and Methods) in mock, TRAPPC2 TRAPPC3, TRAPPC8, and TRAPPC9-depleted cells treated with SA. Data are shown in box-and-whisker plots: Box-plot central line, median; box limits, upper and lower quartiles; whiskers show the minimum to maximum. N=3. ***p<0.001, ****p<0.0001, One-way ANOVA with Dunnett's multiple comparison test.

B. HeLa cells microinjected with control IgG or a TRAPPC3-specific antibody (right panels in green) were treated with SA. The TRAPPC3 Ab disrupts the Golgi (Yu et al, 2006), monitored using an anti-TGN46 Ab. Anti-G3BP was used to stain SGs. The graph shows quantification of the SG area. Mean ± s.e.m. three independent experiments; n>80. ****p<0.0001, Student's unpaired two-tailed t-test. Scale bar, 10 µm.

C. Structured Illumination Microscopy (SIM)-Super resolution (SR) images of endogenous TRAPPC2 and GFP-Sec23 localizing at SGs, stained for G3BP. Scale bar 5 µm. Right, magnification of boxed area. Scale bar, 0.5 µm.

D,E. Localization of Raptor (D) and RACK1 (E) in mock, TRAPPC3-KD and TRAPPC2-KD HeLa cells treated with SA. G3BP was used to stain SGs. Scale bar, 10 µm. Each graph shows the quantification (mean intensity) of the respective protein in SG spots expressed as a percentage of the mock (TRL). Mean ± S.D. three independent replicates. *p<0.02; **p<0.009 in (D), *p<0.05; ****p<0.0001 in (E), One-way ANOVA with Dunnett's multiple comparison test.

F,G. Immunoprecipitation (IP) with an anti-TRAPPC2 Ab or IgG from cells with or without SA treatment, as indicated, followed by SDS-PAGE and Western blot with ant-Raptor (F) or anti-RACK1 (G) Abs. Input: cell lysate (40 µg for TRAPPC2, 10 µg for RACK1 and Raptor).

H,I. Localization of Raptor (H) and RACK1 (I) in untreated cells or cells pre-treated with the indicated CDK inhibitor (1 µM, 150 min) and then with SA (300 µM, 30 min). G3BP was used to stain SGs. Scale bar, 10 µm. Graphs show quantification of the localization of the respective protein with SGs, expressed as a percentage of the control. Mean ± s.e.m. of one representative experiment out of three independent replicates, n=60-80. ****p<0.0001, One-way ANOVA with Dunnett's multiple comparison test.

J. Analysis of cell death after overnight recovery of HeLa cells treated or untreated with CDKi (SNS-032; Flavopiridol or Dinaciclib, 1 µM, 150 min) and then treated or not with SA (500 µM, 3 h). Images were acquired automatically by OPERETTA microscope. Values indicate the percentage of the total number of nuclei (stained with DAPI) positive for BoBo-3 staining. Mean ± s.d. of one representative experiment out of three independent replicates. ns: not significant, ****p<0.0001, One-way ANOVA with Dunnett's multiple comparison test.

K. Analysis of cell death, as described in (J), in HeLa cells that were left untreated, treated with non-targeting siRNAs or siRNAs against TRAPPC2, and in two cell clones knocked out for TRAPPC2, with and without SA treatment. Mean ± s.d. of three independent replicates.
The TRAPP complex mediates secretion arrest induced by stress granule assembly (2019)
Figure 8

Figure 8.

The sequestering of TRAPP and COPII in SGs slows down ER export

A. Left, control or SA-treated (500 µM, 120 min) human fibroblasts (HFs) were incubated at 40°C for 180 min and stained for eIF3, PCI, and Sec24C. Right, the cells were imaged 10 min after shifting the temperature from 40°C to 32°C and stained for eIF3, PCI, and Giantin (to label the Golgi).

B. HeLa cells were exposed to SA (200 µM) for the indicated time, alone or in combination with ISRIB and SGs were analyzed. Quantification of SG area (µm) of three independent experiments. Mean ± s.e.m. n = 60-80 cells per experiment, N = 3.

C. Quantification of Sec24C localization at SGs over time (the ratio between Sec24C (mean fluorescence intensity) in SG puncta and cytosolic Sec24C). Mean ± SD. n = 60-80 cells per experiment, N = 3.

D. HeLa cells expressing VSV-G-UVR8 mEOS were left untreated or treated with SA alone or in combination with ISRIB (1 µM) (120 min ISRIB pre-treatment and 30 min SA+ISRIB) and then pulsed with blue light. Images were taken 10 min after the UV pulse and processed for staining with the indicated markers.

E. Cells were treated with SA for 30 min, the SA was washed out (WO), and cells were left to recover for 120 min in the presence of cycloheximide, followed by a blue light pulse and processing for staining as described in (D).

F. Quantification of VSV-G (mean intensity) in the Golgi area to the total VSV-G per cell under the conditions described in (D,E). Data are expressed as percentage of the control. Mean ± s.e.m. of three independent experiment. ****p<0.0001; ns: not significant, One-way ANOVA with Dunnett's multiple comparison test.

Data information: (A, D, E) Scale bars, 10 µm.
The TRAPP complex mediates secretion arrest induced by stress granule assembly (2019)
Figure 9

Figure 9.

The sequestering of TRAPP in SGs induces the fragmentation of the GC in a Rab1-dependent manner

A. AiryScan images of HeLa cells treated with SA for the indicated times and stained with GM130 (gray). Scale bar, 10 µm. The graph shows quantification of Golgi objects in SA-treated cells. Mean ± s.e.m. of three independent experiments. n=90-100. ****p<0.0001; ns: not significant, Student's unpaired two-tailed t-test.

B. Control cells and cells treated with Dinaciclib (CDKi) were treated with SA and stained for GM130 (in gray). Insets, eIF3. Blue, nuclear DAPI staining. The graph shows quantification of Golgi objects in HeLa cells untreated or treated with SNS-032, Flavopiridol, or Dinaciclib for 150 min and then treated with SA (300 µM, 30 min). Mean ± s.e.m. of three independent experiments. ****p<0.0001, One-way ANOVA with Dunnett's multiple comparison test.

C. Quantification of Golgi objects in cells plated at different percentage of confluency and treated or untreated with SA. Mean ± s.e.m. of three independent experiments. **p<0.001; ***p<0.0002; ns: not significant, One-way ANOVA with Dunnett's multiple comparison test.

D. Quantification of Golgi objects in cells pre-treated with ISRIB (1 µM) for 3 h and then exposed to SA (30 min) in the presence of ISRIB. ***p<0.002, Student's unpaired two-tailed t-test.

E. Electron microscopy images of cells treated (300 µM, 30 min) or untreated with SA. The arrow indicates the Golgi complex. Scale bar, 200 nm.

F. AiryScan images of HeLa cells at steady state or exposed to SA for the indicated times. A Rab1-GTP specific antibody was used to monitor the pool of active Rab1, and GM130 to stain the Golgi complex. Insets, eIF3. Scale bar, 10 µm. The graph shows quantification of Rab1-GTP at the Golgi complex expressed as a percentage of the control. Mean ± s.e.m. of three independent experiments. *p<0.011, **p<0.002, Student's unpaired two-tailed t-test.

G. HeLa cells transfected or not with WT GFP-Rab1B were left untreated or treated with SA and stained for GM130 and G3BP to monitor SGs. Dashed white line, WT GFP-Rab1B transfected cells. Scale bar, 10 µm. The graph shows quantification of Golgi objects in the different conditions. NT: non-transfected. Mean ± s.e.m. of three independent experiments. ****p<0.0001, Student's unpaired two-tailed t-test.

Expanded View Figure Legends
Mammalian UPF3A and UPF3B can activate nonsense-mediated mRNA decay independently of their exon junction complex binding (2022)
Figure 1

Fig 1. Loss of UPF3B in human cells affects EJC-dependent NMD.

A. Schematic of UPF3B mutagenesis strategies using CRISPR-Cas9. UPF3B locus is in black where rectangles represent exons and horizontal line denotes introns; coding region is shown as wider rectangles. Red arrowheads represent guide RNA targeting sites. Top: two guide RNAs delete the UPF2 binding domain (2BD) of UPF3B protein coding region as shown to create 3BΔ2BD cells. Bottom: a donor template is used to insert puromycin resistant gene (PuroR) and bovine growth hormone (BGH) polyadenylation signal at the cut site to generate UPF3B knockout (3BKO) cells.

B. Immunoblot of parental wild-type (WT) and UPF3B mutant cell lines showing levels of proteins on the right. In 3BΔ2BD, a smaller UPF3B protein with deletion of amino acids 20-155 (UPF3BΔ20-155) is expressed. Relative Expression (Rel Exp) of this deletion protein as compared to the full-length UPF3B along with standard error of mean (SEM) are indicated below lane 2. UPF3B antibody recognizes antigen outside the deleted region in 3BΔ2BD. HNRNPA1 is used as a loading control. ND = UPF3B levels not determined.

C. Cumulative Distribution Function (CDF) plots of PTC+ isoforms and PTC- isoforms from the same set of genes. X-axis represents fold change in 3BΔ2BD versus WT cells each with control knockdown (siNC). Number of transcripts in each set (n) and p-value from Kolmogorov-Smirnov (KS) test comparing the two distributions are shown.

D. Bar plots from isoform specific RT-qPCR analysis showing average fold change (y-axis) of PTC+ and PTC- isoforms from genes indicated on the bottom in WT and the two UPF3B mutant cells identified in the legend on the top right. For each isoform, levels in mutant cells are compared to the levels in WT cells (set to 1). Relative levels from each replicate are shown by white circles. Error bars indicate standard errors of means. The asterisk (*) represents p<0.05 in t-test with null hypothesis of true mean being 1 (n=3 biological replicates).

E. Cumulative Distribution Function (CDF) plots of NMD+ isoforms and NMD- isoforms. X-axis represents fold change in 3BΔ2BD versus WT cells each with control knockdown (siNC). Number of transcripts in each set (n) and p-value from Kolmogorov-Smirnov (KS) test comparing the two distributions are shown.

F. Cumulative Distribution Function (CDF) plots of PTC+ isoforms and PTC- isoforms from same set of genes. X-axis represents fold change in UPF1 knockdown (siUPF1) versus control knockdown (siNC) in 3BΔ2BD cells. Number of transcripts in each set (n) and p-value from Kolmogorov-Smirnov (KS) test comparing the two distributions are shown.

G. Cumulative Distribution Function (CDF) plots of NMD+ isoforms and NMD- isoforms. X-axis represents fold change in UPF1 knockdown (siUPF1) versus control knockdown (siNC) in 3BΔ2BD cells. Number of transcripts in each set (n) and p-value from Kolmogorov-Smirnov (KS) test comparing the two distributions are shown.
Mammalian UPF3A and UPF3B can activate nonsense-mediated mRNA decay independently of their exon junction complex binding (2022)
Figure 2

Fig 2. UPF3A activates NMD in the absence of UPF3B.

A. Immunoblots showing levels of proteins on the right in input or FLAG immunoprecipitates (IP) from WT and UPF3B mutant cells expressing endogenously FLAG-tagged UPF1 protein as indicated above each lane. The presence of RNase A during FLAG-IP is indicated above each lane. The asterisk (*) represents p<0.05 in t-test with null hypothesis of true mean being 1.

B. Immunoblots showing levels of proteins (right) in input and IP with normal rabbit IgG (IgG-IP) or antibody targeting EIF4A3 (EIF4A3-IP) from WT and UPF3B mutant cells. The asterisk (*) represents p<0.05 in t-test with null hypothesis of true mean being 1.

C, D. CDF plots of (C) PTC+ and PTC-isoforms, (D) NMD+ and NMD- isoforms. X-axis represents fold change upon UPF3A knockdown (siUPF3A) versus negative control knockdown (siNC) in WT cells. Number of transcripts in each set (n) and p-value from KS test comparing the two distributions are shown on each plot.

E, F. CDF plots of (E) PTC+ and PTC-isoforms, (F) NMD+ and NMD- isoforms. X-axis represents fold change upon UPF3A knockdown (siUPF3A) versus negative control knockdown (siNC) in 3BΔ2BD cells. Number of transcripts in each set (n) and p-value from KS test comparing the two distributions are shown on each plot.

G, H. CDF plots of UPF3B-dependent (G) and -independent (H) PTC+ isoforms and their respective PTC- isoforms. X-axis represents fold change upon UPF3A knockdown (siUPF3A) versus negative control knockdown (siNC) in 3BΔ2BD cells. Number of transcripts in each set (n) and p-value from KS test comparing the two distributions are shown on each plot.

I. CDF plots of UPF3B-dependent and UPF3B-independent NMD+ isoforms as compared to NMD- isoforms. X-axis represents fold change upon UPF3A knockdown (siUPF3A) versus negative control knockdown (siNC) in 3BΔ2BD cells. Number of transcripts in each set (n) and p-value from KS test comparing the two distributions are shown on each plot.

J. Bar plot showing average fold change as measured by isoform specific RT-qPCR of PTC+ and PTC- isoform from genes indicated on the bottom in WT and two independent clones of 3AKO, 3BΔ2BD, 3BKO, and 3DKO cells. Relative levels from each replicate are shown by white circles. Error bars indicate standard errors of means. The asterisk (*) represents p<0.05 in t-test with null hypothesis of true mean being 1 (n=3 biological replicates).