Figure 1.

TG Induces Golgi Fragmentation and UPR

(A) Short-term TG treatment causes Golgi fragmentation. HeLa cells were treated with 250 nM TG, fixed at the indicated time points, and stained for GM130 (cis-Golgi) and TGN46 (trans-Golgi). Scale bar, 20 μm.

(B) Quantitation of (A) for cells with fragmented Golgi using GM130 as the Golgi marker.

(C and D) Super-resolution images of DMSO- (C) and TG-treated (D) HeLa cells. Cells were treated with 2 μM TG for 1 h, stained as in (A), and imaged with a Leica SP8 STED microscope. Indicated areas are enlarged and shown on the right as merged GM130 (green) and TGN46 (red). To quantify Golgi unstacking in these images, relative fluorescence intensity was plotted along a random line through the Golgi region. Note the agreement in peaks in control (C) and relative disagreement in peaks in the TG-treated cell (D). Scale bar in main images, 5 μm; in inserts, 1 μm.

(E) Longer term TG treatment results in ER stress. Cells treated as in (A) were analyzed by Western blot of indicated proteins. Note that TG treatment increases the levels of p-eIF2α, Bip, and CHOP.

(F–G) Quantitation of the ratio of p-eIF2α/eIF2α and the Bip levels from (E), with the no-treatment control normalized to 1.

All quantitation results are shown as mean ± SEM from at least three independent experiments; statistical analyses were performed using two-tailed Student's t-tests (∗p ≤ 0.05; ∗∗p ≤ 0.01; ∗∗∗p ≤ 0.001).