Bacterial ligands trigger depolymerization of the filamentous K6a network. (A) Confocal microscopic images of hTCEpi cells treated with vehicle, flagellin (FliC; 0.5 µg/ml), LPS (1 µg/ml), or LTA (1 µg/ml) for 16 h followed by immunostaining for K6a (green) and counterstaining for nuclei (red). For cells treated with LPS, a 2-h pretreatment with IFN-γ (250 ng/ml) was used to induce LPS responsiveness. The intense filamentous K6a network staining surrounding the nucleus in the control cell (insets) became diffused and weak after stimulation with bacterial ligands. Bars, 10 µm. (B) Quantification of fluorescence signal intensity of K6a filament as a function of the distance (μm) from the nucleus toward the plasma membrane using ImageJ. Signal intensity of each cell was measured along three lines at 0.06 µm steps to obtain a mean. The intensity values were normalized to the nuclear signal. Means ± SEM of 11–14 cells pooled from three to four independent experiments are shown. K6a filament intensity of treated cells was reduced significantly compared with control (P < 0.0001).