Figure 9

Increase of paracellular resistance after CK2-dependent phosphorylation of occludin. Two-path impedance spectroscopy was applied to measure the two components of epithelial resistance (R^epi), paracellular resistance (R^para, reflecting the pathway across the tight junctions) and transcellular resistance (R^trans, reflecting the pathway across the cell membranes). Measurements were done in MDCK C11 cells, which were stably transfected with the indicated occludin-FLAG₃ constructs. In Occ-FLAG₃-T400E/T404E/S408E-transfected cells a dramatic increase in R^para was detectable compared to wildtype occludin and to Occ-FLAG₃-T400A/T404A/S408A-transfected cells, while R^trans was unchanged. Due to the about fourfold increase of R^para, the overall epithelial resistance R^epi was also increased. The figure shows combined results of 6 independent measurements on two clones of each construct. ** p < 0.01.