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Figure 1. APO modulates FGF-2 expression in cultured astrocytes through activation of cAMP/PKA and MEK/MAPK but not PI-3K signaling pathways. A) Phosphorylation of PKA is activated by addition of APO in the cultures. Astrocytes stimulated by APO were harvested at different time points (30 min, 60 min, 2 h, and 6 h). Supernatants were assayed for PKA phosphorylation. B) Quantitation of A. *P < 0.05, compared with untreated. C) Effects of cAMP activators and inhibitors of PKA, PKC, MAPK, or PI-3K on APO-induced FGF-2 expression in striatal astrocytes. Cultures were exposed to HA-100 (30 µM, PKA/PKC inhibitor), LY294002 (20 µM, PI-3K inhibitor), PD98059 (50 µM, MAPK inhibitor), KT5720 (50 µM, PKA inhibitor), or GF109203X (2 µM, PKC inhibitor) for 2 h, followed by addition of APO for 6 h, while striatal astrocytes were treated only with forskolin (5 µM, cAMP activator) and APO. Cells were then lysed for Western blot analysis. Bottom) The levels of 
-tubulin are shown as a loading control. D) Quantitation of C. *P < 0.05, compared with untreated. E) The MEK/MAPK, but not the PI-3K signaling pathway, was activated following APO stimulation. Serum-starved striatum astrocytes were stimulated with APO, and levels of phospho-MAPK, MAPK, phospho-Akt (Ser-473) and Akt were assayed by Western blot analysis. Bottom) The levels of -tubulin are shown as a loading control. F) Treatment of cultures with FGF-2 (1 ng/ml) or BDNF does not affect FGF-2 expression.
