Figure 7. Transcription factor activities involved in mediating NaCl-induced expression of the c-Fos gene in RPE cells. mRNA levels were determined with real-time reverse transcription (RT)–PCR analysis in cells cultured for 2 h in iso- (control) and hyperosmotic (+ 100 mM NaCl) media, and are expressed as folds of the unstimulated control. A: The level of c-Fos mRNA was determined in cells cultured in the presence of the following inhibitory compounds: the AP-1 inhibitor SR11302 (5 µM), the cAMP response element-binding protein (CREB) inhibitor 666–15 (250 nM), a HIF inhibitor (HIF-Inh; 5 µM), the STAT3 inhibitor Stattic (1 µM), and the nuclear factor (NF)-κB inhibitor CAPE (5 µM). B, C: mRNA levels were determined in cells transfected with nuclear factor of activated T cell 5 (NFAT5) siRNA (siNFAT5; 5 nM) and non-targeted siRNA (siNon; 5 nM), respectively. B: Transfection of RPE cells with NFAT5 siRNA for 48 h resulted in a reduction of the NFAT5 mRNA level in cells cultured for 2 h in iso- and hyperosmotic media. Non-targeted siRNA had no effects. As negative control, transfection reagent (TR) without siRNA was tested. C: Knocking down NFAT5 with siRNA reduced the level of c-Fos mRNA under hyperosmotic conditions. Each bar represents data obtained in three to nine independent experiments using cell lines from different donors. Significant difference versus unstimulated control: *p<0.05. Significant difference versus NaCl control: ●p<0.05. ○ p<0.05.