Fig. 1.

Thapsigargin and tunicamycin treatment causes ER stress and regulates D2 activity and protein levels. Chemical ER stress causes a rapid loss in D2 levels in different cell models. A, D2 activity and BiP protein levels (inset, D = vehicle and Th = 300 nm thapsigargin) in MSTO-211H cells treated with increasing doses of thapsigargin for 1 h. B, D2 activity and CHOP protein levels (inset) in MSTO-211H cells treated with increasing doses of tunicamycin for 3 h. C, D2 mRNA levels in MSTO-211H cells treated with either increasing doses of thapsigargin (Th) for 1 h or 0.6 μm tunicamycin (Tun) for 3 h. D, D2 activity and BiP protein levels (inset, D = vehicle and Th = 300 nm thapsigargin) in HEK-293 treated with increasing doses of thapsigargin for 1 h. D2 activity was normalized to ß-galactosidase activity and is expressed as relative to control group. E, FLAG-CysD2 activity and protein (inset) levels in HEK-293 cells treated with vehicle (D) or 300 nm thapsigargin (Th) for 6 h. Both vehicle and thapsigargin-treated cells were exposed to 50 nm free T₄. Gel loading was corrected to protein concentration. All values are displayed as ± sem and are representative of three experiments, where * represents P < 0.01 vs. nontreated group by one-way ANOVA followed by Dunnett's multiple-comparison test. In panel E, † represents P = 0.056 vs. vehicle-treated group by two-tailed Student's t test.