AvrA expression stabilizes the protein expressions of occludin and ZO-1 <i>in vitro</i>.

<p>(A) Western blot of occludin-1, ZO-1, claudin-1, and E-cadherin. Polarized human colonic epithelial T84 cells were colonized with AvrA-deficient or -sufficient bacterial strains for 30 minutes, washed with HBSS and incubated in DMEM for 30 minutes. Cells were lysed. Equal volumes of total cell lysate were processed for immunoblotting with Rabbit anti-claudin-1, Mouse anti-occludin-1, Mouse anti-ZO-1 antibodies, or E-cadherin antibodies. Experimental groups: Control: polarized T84 cells without any treatment; WT: wild-type <i>S</i>. Typhimurium ATCC 14028s without sufficient AvrA protein expression; PhoP^c: parental PhoP^c with sufficient AvrA protein expression; AvrA⁻: PhoP^c AvrA mutant; AvrA⁻/AvrA⁺: PhoP^c AvrA- transcomplemented with a plasmid encoding WT AvrA; or <i>E.coli</i> F18: commensal bacteria isolated from human intestine. (B) Densitometry of occludin and ZO-1. Relative occludin-1 and ZO-1 band intensity was determined using NIH Image 1.63 software. Occludin-1 and ZO-1 expression significantly increased in the PhoP^c group compared to the Control, WT, and AvrA- groups in absence of AvrA protein. * P<0.05. Data are reported as mean±SD of 3 independent experiments.