Journal: The EMBO Journal
Article Title: Spatially targeted chemokine exocytosis guides transmigration at lymphatic endothelial multicellular junctions
doi: 10.1038/s44318-024-00129-x
Figure Lengend Snippet: Figure 7 is shown with alternative colors (non-red and -green) in Appendix Fig. . ( A ) Quantification of the CCL21ΔC-mCherry exocytosis events at the LEC junctions in EGFP or EGFP-RAB8A DN expressing LECs. The dot plot shows the mean number of exocytosis events/cell ± SD. Data points represent n = 3 independent experiments, comprising of, altogether, 24 LECs in 12 biological replicates. ( B ) Quantification of the effect of EGFP-RAB8A DN expression on CCL21ΔC-mCherry intensity in the media. The dot plot shows CCL21ΔC-mCherry mean intensity ± SD, and normalized to the average of controls, which was set at 1 in each experiment. The data points represent n = 11 biological replicates in three independent experiments. ( C – F ) Shows a LEC monolayer expressing CCL21ΔC-mCherry (red) and EGFP, EGFP-RAB8A DN, or EGFP-RAB8A WT (green). LECs were stained for VE-cadherin (magenta) and nuclei (DAPI, blue). Quantification of the mean CCL21ΔC-mCherry intensity ± SD at the multicellular junctions of EGFP-mCherry double-positive LECs ( D ) per biological replicate and ( E ) per multicellular junction. Whereas the dot plot in ( F ) shows the mean CCL21ΔC-mCherry intensity ± SD measured in the whole LEC. The results were normalized to the average of controls, which was set at 1, in each experiment. The data points represent n = 6 biological replicates in three independent experiments or n = 149 (EGFP), n = 153 (EGFP-RAB8A DN), and n = 147 (EGFP-RAB8 WT) multicellular junctions in ( D , E ) and 212 (EGFP), 188 (EGFP-RAB8A DN), and 170 (EGFP-RAB8 WT) LECs in ( F ). ( G ) Immunofluorescence images of a LEC monolayer expressing CCL21ΔC-mCherry (red) and either EGFP or EGFP-RAB8A DN (green). The cells were stained for endogenous RAB6 (gray), and nuclei (DAPI, blue). The data represents n = 4 biological replicates from 2 independent experiments. ( H – K ) Shows TNF-α treated LEC monolayer expressing EGFP (control), EGFP-RAB8A DN, or EGFP-RAB8A WT (green). LECs were stained for CCL2 (red), VE-cadherin (magenta), and DAPI (blue). Quantification of the mean CCL2 intensity ± SD at the multicellular junctions ( I ) per biological replicate and ( J ) per multicellular junction. Whereas the dot plot in ( K ) shows mean CCL2 intensity ± SD measured in the whole LEC. The data was normalized to the average of controls (set at 1) in each experiment. The data points represent n = 6 biological replicates from 3 independent experiments or n = 204 (EGFP), n = 202 (EGFP-RAB8A DN), and n = 192 (EGFP-RAB8 WT) multicellular junctions in ( I , J ), and 242 (EGFP), 240 (EGFP-RAB8A DN), and 136 (EGFP-RAB8 WT) LECs in ( K ). (L , M ) A capture of live recording of LEC monolayer expressing CCL21-mCherry and either of EGFP or EGFP-RAB8A DN (green) and stained for VE-cadherin (magenta). The nuclei of dendritic cells (DC) are stained with Hoechst (blue). ( M ) Quantification of the mean DC transmigration efficiency ± SD on LEC monolayer co-expressing either EGFP (control) or EGFP-RAB8A DN together with either CCL21-mCherry or CCL21 ΔC-mCherry. The results were normalized to the average of control (set at 1) in each experiment. The data points represent n = 10 CCL21-mCherry + EGFP (total of 3285 DCs), n = 9 CCL21-mCherry + EGFP-RAB8A DN (2552 DCs), n = 12 CCL21 ΔC-mCherry + EGFP (7123 DCs), and n = 12 CCL21 ΔC-mCherry + EGFP-RAB8A DN (5535 DCs) biological replicates, across 4 independent experiments. The data in ( L , M ) is related to the Movie . Data information: In mCherry channel-only images in ( C ), the cell borders of all the EGFP-mCherry, double-positive LECs, are indicated with green dashed lines. Similarly, in ( H ) the green dashed lines indicate the cell borders of all EGFP-CCL2 double-positive LECs. Cell borders in ( G ) are shown with white dashed line. In ( C ), ( G ), and ( H ), yellow arrows indicate the multicellular junction shown in the zoom-in images and the white arrowheads the accumulation. In ( A , B ), ( D ), ( F ), ( I ), ( K ), ( M , CCL21 ΔC-mCherry samples), the p -values were calculated using a parametric T-test with Welch’s correction, and in ( E ), ( J ), and ( M , CCL21-mCherry samples) using Mann–Whitney’s test. Scale bars in ( C , G and H ) are 20 µm in overview images and 5 µm in zoom-in images and in ( L ) 50 µm. .
Article Snippet: The used primary antibodies were: a mix of rat anti-mouse VE-cadherin (Biolegend, 138003; dilution of 1:100) and rat anti-mouse VE-cadherin (Invitrogen, 14-1441-81; 1:100) (Figs. and ; Appendix Fig. ); goat anti-mouse CCL21/6Ckine biotinylated antibody (R&D BAF457; 1:300) (Fig. and Appendix Fig. ); rabbit anti-RAB6 (D37C7, Cell signaling, 9625S; 1:100) (Fig. ; Appendix Fig. ); rat anti-mouse LYVE1 (R&D, MAB2125; 1:300) (Fig. ); rabbit anti-mouse LYVE1 (a kind gift from Dr. Kari Alitalo lab (Karkkainen et al, ); 1:1000) (Fig. ).
Techniques: Expressing, Staining, Immunofluorescence, Control, Transmigration Assay