FIGURE 5.

Inhibition of SOCE sensitizes parental Jurkat cells to IFN-α-induced apoptosis. A, intracellular Ca²⁺ concentration was measured in parental Jurkat cells stably expressing empty vector or Orai1 E106A-CFP. Cells were loaded with 2.5 μm fura-2/AM. Thapsigargin (Tg, 2 μm) or Ca²⁺ (1 mm) was added or removed as indicated. B, parental Jurkat cells stably expressing empty vector or Orai1 E106A-CFP were left untreated or treated with 1000 units/ml IFN-α for 48 h, and then stained with Hoechst (blue) and annexin-V (red). Apoptotic cells are shown as red. C, percent apoptosis was calculated by counting the number of annexin V-positive cells divided by the total number Orai1-CFP-positive cells, from three individual experiments. D, parental Jurkat cells were left untreated, treated with IFN-α alone or pretreated with 3 μm BTP2 for 1 h, followed by treatment with or without IFN-α for 72 h. Quantification of apoptotic cells was measured by flow cytometric analysis of dually stained cells with annexin-V-FITC and propidium iodide. E, same as in D except cells were pretreated with 0.6 mm EGTA. Results from three individual experiments are shown as mean ± S.E.