FIG 2.

Glucose deprivation induces ER stress and TRAIL receptors. (A) HeLa cells were incubated with glucose and/or Q-VD (Q-VD+) or DMSO (Q-VD−) as indicated for 24, 48, and 72 h and collected for Western blotting of GRP78, ATF4, and CHOP. (B) HeLa cells were treated with thapsigargin (Tg) for 24 h or incubated in the presence (+) or absence (−) of glucose for the indicated times and collected for reverse transcription-PCR analysis of unspliced and spliced XBP1. (C) HeLa cells were incubated with glucose and/or Q-VD (Q-VD+) or DMSO (Q-VD−) as shown for the indicated times and then collected for Western blotting of DR4 (TRAIL-R1) and DR5 (TRAIL-R2). (D and E) HeLa cells were incubated with or without glucose for the times shown and collected for qPCR analysis. DR4 mRNA levels relative to the values for the housekeeping gene and time zero (T0) are reported in panel B. DR5 mRNA levels relative to the values for the housekeeping gene and time zero (T0) are reported in panel C. The averages and SEM of data from at least three experiments are shown. (F and G) HeLa cells were plated for immunofluorescence, and 24 h later, they were incubated with or without glucose for 24 h before performing confocal analysis of DR5 and GM130 (F) or calnexin (G) localization. *, P < 0.05; **, P < 0.01; N.S., not significant.