FIGURE 2.

Store-operated Ca²⁺ entry in MIN6 cells is regulated by STIM1. A, Western blotting shows expression of STIM1 in MIN6 cells and knockdown of STIM1 protein expression by shRNA-STIM1 (sh) relative to either wild-type MIN6 cells (wt) or cells with shRNA-scr (ss). Expression of STIM1 was reconstituted in the shRNA-STIM1 cells by transduction with an adenovirus expression vector encoding the human isoform of STIM1 (av). The left lane shows M_r markers and then duplicate lanes for each cell line. Anti-STIM1 is shown in the top part of the gel and anti-actin as a loading control in the lower part. B, stable MIN6 cell lines were treated using the protocol shown in Fig. 1A. Traces show only the records immediately before and after reintroduction of Ca²⁺ (indicated by open bar). SOCE in shRNA-STIM1 cells (sh) is inhibited relative to shRNA-scr (ss) and was partially rescued by adenoviral transduction with human STIM1 (av). Traces show the mean ± S.E. The peak SOCE amplitude (C) and AUC for the first 100 s after Ca²⁺ addition (D) were quantified for ss, sh, and av cells (28, 26 and 139 cells, respectively). Both peak and AUC were significantly reduced for sh cells relative to ss cells and were significantly recovered by av (*, p = 0.05; **, p < 0.01, ANOVA).