Figure 2

Induction of ER stress in EL4 cells. (A) UPR activation induced by palmitate treatment. EL4/HEL-Cyto-SIINFEKL cells were either non-treated or treated with 0.25 mM of palmitate or 2.5 μg/ml of tunicamycin for 18 hours. BiP, XBP-1 and CHOP mRNA levels were analyzed by RT-qPCR. Expression levels were normalized to the endogenous control gene β-actin. Transcript levels of treated cells were compared with basal mRNA values of untreated cells (dotted line), which were set to 1. (B) UPR activation induced by glucose deprivation. EL4 stable cell lines were incubated in DMEM medium lacking glucose or containing low glucose (1 mg/ml) or high glucose (4.5 mg/ml) for different durations. BiP, XBP-1 and CHOP mRNA levels were analyzed by RT-qPCR. Expression levels were normalized to the endogenous control gene β-actin. Transcript levels of cells incubated under low (purple) or no glucose (green) were compared to levels of cells grown in high glucose medium (dotted line), which were set to 1. Similar results were obtained with EL4/HEL-ER-SIINFEKL cells (data not shown). Bars represent the mean and SD from three independent experiments performed in triplicate. *P < 0.05 when comparing untreated with palmitate- or tunicamycin-treated cells, or high glucose with low glucose or no glucose conditions.