FIG. 2.

Store-operated Ca²⁺ influx is impaired in fibroblasts and T and B cells from C57BL/6 background ORAI1-deficient mice. (A) Store-operated Ca²⁺ influx in wild-type (WT), Orai1 heterozygous (+/−), and Orai1 homozygous null (−/−) MEF cells stimulated with 1 μM thapsigargin (TG) in Ringer solution containing the indicated Ca²⁺ concentrations (mM). (B) Heterozygous Orai1^+/− B and T cells show a substantial decrease in store-operated Ca²⁺ influx. (Left) Store-operated Ca²⁺ influx in naïve B cells in wild-type littermates (WT) and heterozygous Orai1^+/− mice (+/−) in response to TG (1 μM) or anti-IgM in the presence of indicated [Ca²⁺]_o (mM). (Right) Store-operated Ca²⁺ influx in response to TG (1 μM) or anti-CD3 cross-linking with goat anti-hamster IgG (GαH) in differentiated CD4⁺ T cells (T_HN) from wild-type littermates (WT) and heterozygous Orai1^+/− mice in the presence of indicated [Ca²⁺]_o. (C) Decrease in store-operated Ca²⁺ influx in wild-type (WT) or Orai1^−/− (KO) B and T cells obtained from fetal liver chimeras. Peripheral B and T cells from reconstituted mice were treated with TG (1 μM). Left, B cells (B); middle, differentiated CD4⁺ T cells (T_HN); right, differentiated CD8⁺ T cells (cytolytic T cells [CTLs]). For all experiments, Ca²⁺ influx was analyzed by single-cell video imaging of fura-2-labeled cells. The traces show the average results for more than 100 cells analyzed in each experiment. All the data shown are representative of at least three independent experiments. α, anti. In all panels, the bars above the traces indicate the point at which the cell perfusion medium was changed and the duration of time that the indicated substance, stimulus, or [Ca²⁺]_o was present.