Figure 6. Exocytic SNARE complex formation is impaired in E. coli exposed mast cells.
(A) RBLs were cultured with or without (control) E. coli for 2h at an MOI of 10,000. The cells were harvested and stimulated for 30min with 1μM PMA/1μM Ionomycin at a concentration of 2×106 cells/ml. Cells were treated with 1mM NEM for 15min. Next, NEM was inactivated with 2mM DTT for 15min on ice. NEM-treated cells were washed and lysed. 1mg of total protein was immunoprecipitated using anti-SNAP23 antibody. Samples were analyzed by Western blot using anti-SNAP23, -Syntaxin4, -VAMP8, and –VAMP2 antibodies. Each blot is representative of at least 3 independent experiments. (B) Quantification of the mean band intensity ratio’s of the indicated protein to SNAP23 ± the standard deviation of at least 3 independent experiments. The protein:SNAP23 ratio of the control population was considered 100%. Asterisks denote statistically significant p values, where * ≤ 0.05 and ** ≤ 0.01. (C) 40μg of total protein from exposed or control whole cell lysates was analyzed by Western blot as described in A.