Figure 2.
Low Concentration of TG Induces Golgi Fragmentation Prior to UPR Through Elevated Cytosolic Ca2+
(A) HeLa cells were treated with the indicated concentrations of TG for 20 min and stained for GM130. Scale bar, 20 μm.
(B) Quantitation of cells with fragmented Golgi in (A).
(C) Cells treated with TG as in (A) were analyzed by Western blots.
(D and E) Quantitation of p-eIF2α/eIF2α and Bip in (C) from five independent experiments.
(F) BAPTA-AM inhibits TG-induced Golgi fragmentation. HeLa cells treated with 100 nM TG for indicated times with or without 60 μM BAPTA-AM (B/AM) and stained for GM130. Scale bar, 20 μm.
(G) Quantitation of (F) from three independent experiments. Statistical analyses were performed using two-tailed Student's t tests (∗, p ≤ 0.05; ∗∗, p ≤ 0.01; ∗∗∗, p ≤ 0.001).
(H) Electron micrographs of Golgi profiles in HeLa cells treated with 250 nM TG and B/AM for 20 min. Note that the Golgi is comprised of bulbous saccules in the TG-treatment, whereas in the B/AM pretreated cells the cisternae appear straight and well-stacked. Asterisks (∗) indicate nuclei. Scale bar, 0.5 μm.
(I) Quantitation of the morphological features of Golgi stacks on the EM images in (H). For statistics, B/AM and TG were compared with DMSO treatment, whereas TG + B/AM was compared with TG treatment.