Yip1A is required for the activation of the IRE1 pathway and the upregulation of Sar1, Sec23 and Sec24D during infection with B. abortus.

HeLa cells were infected with B. abortus, and then transfected with each siRNA at 1 hr p.i. 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-D) Relative protein levels of pIRE1 (B) and spliced-XBP1 (C), and relative mRNA levels of spliced-XBP1 (D) in control (solid circles) and Yip1A-knockdown (open circles) cells. The protein levels at time 0 hr were assigned the value 1. Data are means ± SD from three independent experiments. (E) Representative immunoblots for pPERK, cleaved-ATF6, and GAPDH, and relative protein levels of pPERK and cleaved-ATF6 in control (solid bars) and Yip1A-knockdown (open 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 tunicamycin for 8 hr (‘Tm’). The protein levels at time 0 hr were assigned the value 1. Data are means ± SD from three independent experiments. (F) Representative immunoblots for Sar1, Sec23, Sec24D, and GAPDH, and relative protein levels of Sar1, Sec23, and Sec24D in control (solid bars) and Yip1A-knockdown (open bars) cells at 24 hr p.i. 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. (G) Representative immunoblots for Sar1, Sec23, Sec24D, and GAPDH, and relative protein levels of Sar1, Sec23, and Sec24D in control (solid bars) and IRE1-knockdown (open bars) cells at 24 hr p.i. 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.