Fig. 3

S-layer protein-coated or uncoated cell wall fragments dissimilarly counteract F4⁺ETEC-induced injury of membrane barrier. Caco-2/TC7 cells were untreated (control, C), infected with F4⁺ETEC (E), treated with S-layer protein-coated (S-CWF) or uncoated cell wall fragments (U-CWF), co-treated with S-CWF or U-CWF and E (S-CWF + E or U-CWF + E, respectively), pre-treated with S-CWF or U-CWF before F4⁺ETEC infection (prS-CWF + E or prU-CWF + E, respectively). Cell lysates were fractionated by SDS-PAGE and transferred to nitrocellulose filters. The membranes were incubated with mouse monoclonal anti-occludin and rabbit polyclonal anti-β-catenin, anti-phospho (P)-β-catenin, anti-E-cadherin, anti-α-tubulin primary antibodies, and then with horseradish peroxidase-conjugated secondary antibodies. The figure shows a representative Western blot of each protein (panel a) and the densitometric values of the immunoreactive protein bands (panels b–e). The relative expression levels of occludin, β-catenin and E-cadherin were normalized to α-tubulin, whereas the phosphorylated β-catenin was normalized to the corresponding unphosphorylated form. Values represent means ± SD of at least three independent experiments, carried out in triplicate. Statistically significant differences are shown and * indicates P < 0.01 from the control group, ^# indicates P < 0.05 from the ETEC group