IGPR-1 stabilizes cell–cell junctions and stimulates actin stress fiber assembly.
A, PAE cells expressing EV or IGPR-1 were stained with anti-ZO1 antibody (green) and DAPI (blue). An arrowhead indicates ZO1 staining at cell junctions. The ImageJ program was used to quantify ZO1 staining (four field/group). B, the same cells were also stained with anti–IGPR-1 antibody (red) and DAPI for nucleus (blue). A white arrowhead shows IGPR-1 expression in cell–cell contact area. Green arrowheads point to expression of IGPR-1 when cells are not in contact with each other. Image magnification, 10 μm. C, ectopic expression of IGPR-1 in PAE cells. D, HUVECs expressing control (Ctr.) shRNA or IGPR-1–shRNA were stained for ZO1 and DAPI. Quantification of ZO1 staining is shown (four fields/group). E, knockdown of IGPR-1 in HUVECs. Whole-cell lysates expressing control shRNA (Ctr.sh) or IGPR-1–shRNA (IGPR-1-sh) was blotted with anti–IGPR-1 antibody or anti-GAPDH antibody for loading control. F, IGPR-1/PAE and EV/PAE cells were stained with phalloidin (red) for actin, anti-vinculin (green), and DAPI (blue). Scale bar, 10 μm.