Fig. 3
Reduced cell-matrix adhesion in claudin-7 KD cells. a Left panel: Scratches were made on the confluent control and claudin-7 KD cell monolayer. Claudin-7 KD cells were easily peeled off along the scratch as shown in arrows, while the control cells were well attached to the plate. Right panel: When cultured on uncoated glass coverslips, claudin-7 KD formed spheroids while the control cells were able to spread out and formed a monolayer. b Monolayer cultures of control and claudin-7 KD cells were exposed to trypsinization and phase images were taken every minute. Claudin-7 KD cells took less time (4 min) to be fully lifted by trypsin than the control cells (7 min). c Cell attachment assay. Two × 105 control and KD cells were plated to each well of the collagen IV-coated 24-well plates. Four hours later, the unattached cells were washed off and the attached cells were trypsinized and counted. KD cells showed significantly reduced cell attachment compared to the control cells (left). The significantly reduced cell attachment was also observed in T-47D breast cancer cells with claudin-7 knockdown by the same shRNA approach (right). *P < 0.05. The insert shows the knockdown level of claudin-7 in T-47D cells. d Electron microscopy shows a larger gap between claudin-7 KD cells and the coverslip than that between control cells and the coverslip. TJs in both cell lines were largely intact (arrows). Magnifications: top, ×25,000; bottom, ×50,000. e TER measurement indicates that there was no significant change in the barrier function of TJs after claudin-7 was knocked down