Fig. 3

Long-term PNPT1/SUV3 silencing induces dsRNA accumulation in EndoC-βH1 cells but no type I IFN response. EndoC-βH1 cells were transfected with a siRNA control (siQ: white bars) or with siRNAs targeting PNPT1 (siP#1, grey bars), SUV3 (siS, black striped bars) or both (siP/S: grey bars with black stripes), and then maintained in culture for 6 days after transfection. As a positive control for gene expression, in some experiments cells were treated with IFNα (2000 U/ml) for 24 h (red bars). a Protein expression was measured by western blotting and representative images of 2 independent experiments are shown. Densitometry results are shown for PNPT1 (b), pSTAT1 (f) and pSTAT2 (g). e dsRNA accumulation (red) was analyzed by immunocytochemistry. Representative images of 3 independent experiments are shown (magnification 40×). mRNA expression of PNPT1 (c), SUV3 (d), MDA5 (h), HLA-ABC (i), MX1 (j) and CHOP (k) were analyzed by RT-qPCR and normalized by β-actin and then by the value of siQ considered as 1. Results are mean ± SEM of 2–10 independent experiments. *p < 0.05 and ***p < 0.001 vs siQ, Student t test