FIGURE 4.

Induction of the proapoptotic protein DP5 is partially prevented after STAT1 knockdown. INS-1E cells (A) or primary FACS-sorted rat β-cells (B) were transfected and treated as described in Fig. 1. A and B, DP5 mRNA expression was assayed by real-time RT-PCR and normalized for the housekeeping gene GAPDH. Results are mean ± S.E. of four (A) or five (B) independent experiments. C, INS-1E cells were co-transfected with the DP5 promoter luciferase reporter and control pRL-CMV alone (NT) or in combination with si-control, siIRF-1, or siSTAT1. After 1 day of recovery, cells were left untreated or exposed to 10 units/ml IL-1β and 100 units/ml IFN-γ for 24 h as indicated. Results are mean ± S.E. of five independent experiments and represent fold variation as compared with untreated control condition. *, p < 0.05; **, p < 0.01; and ***, p < 0.001 versus untreated (i.e. not treated with cytokines) or untreated transfected with the same siRNA. §, p < 0.05; §§, p < 0.01; and §§§ p < 0.001 versus NT & si-control treated with cytokines at the same time point, ANOVA followed by Student's t test with Bonferroni correction.