FIGURE 1.

FGF2 activates transcription of Gdnf expression in rat astrocytes. A and B, primary cultured rat astrocytes (A) or C6 rat glioma cells (B) were treated with 0 or 10 ng/ml of FGF2 for 12 h. Total RNA was extracted and then subjected to RT-PCR to quantify Gdnf expression. Actin expression was used as an internal control. **, p < 0.01 compared with basal luciferase activity. C, immunodetection of Gdnf. Primary rat astrocytes cultured on coverslips were treated with 0 or 10 ng/ml of FGF2 for 18 h. After incubation with anti-Gdnf (1:100) and anti-S100 (1:200) antibodies, the cells were observed under a confocal fluorescence microscope; green, S-100; red, Gdnf. Arrows indicate immunoreactive cells for Gdnf. D and E, Gdnf promoter constructs (0.2 μg each) were transiently co-transfected with the pRL-null vector (50 ng) into primary rat astrocytes (D) or C6 glioma cells (E). At 24-h post-transfection, cells were treated with 0 or 10 ng/ml of FGF2 for 8 h, and luciferase activity was measured. The firefly luciferase activity was normalized to Renilla luciferase activity. The data represent the mean ± S.D. (error bars) of three independent experiments, each performed in triplicate. *, p < 0.05 compared with basal luciferase activity (Student's t test).