Infection with Brucella abortus activates the IRE1 pathway of the UPR and leads to the upregulation of the COPII vesicle components Sar1, Sec23 and Sec24D.

HeLa cells were uninfected (‘control’) or infected with B. abortus (‘B. abortus’). Cell lysates were collected at the indicated time points and analyzed by Western blotting. (A) Representative immunoblots for pIRE1, spliced-XBP1, and GAPDH. GAPDH was used for normalization. The intensity of the bands was quantified using the MultiGauge software. (B, C) Relative protein levels of pIRE1 (B) and spliced-XBP1 (C) in uninfected control (open circles) and Brucella-infected (solid circles) cells. The protein levels at time 0 hr were assigned the value 1. Data are means ± SD from three independent experiments. (D) Representative immunoblots for pPERK, cleaved-ATF6, and GAPDH, and relative protein levels of pPERK and cleaved-ATF6 in control (open bars) and Brucella-infected (solid bars) cells. GAPDH was used for normalization. The intensity of the bands was quantified using the MultiGauge software, and the results are shown in the bar graphs. As a positive control for activation of PERK or ATF6, HeLa cells were treated with 5 μg/ml of tunicamycin for 8hr (‘Tm’). The protein levels at time 0 hr were assigned the value 1. Data are means ± SD from three independent experiments. (E) Representative immunoblots for Sar1, Sec23, Sec24D, and GAPDH, and relative protein levels of Sar1, Sec23, and Sec24D in control (open bars) and Brucella-infected (solid bars) cells. GAPDH was used for normalization. The intensity of the bands was quantified using the MultiGauge software, and the results are shown in the bar graphs. The protein levels in control cells were assigned the value 1. Data are means ± SD from three independent experiments. *: p<0.05; **: p<0.01.