Figure 5.

Role of PI3K/AKT, JAK/STAT and MAPK/ERK pathways in the effect of ciliary neurotrophic factor (CNTF) on retinal ganglion cells (RGC). CNTF enhances the viability of RGCs via the PI3K/AKT and JAK/STAT pathways, whereas β3-tubulin expression is increased via PI3K/AKT and MAPK/ERK pathways. RGCs were treated with pathway inhibitors, including the PI3K/AKT pathway inhibitor LY294002 (50 µM), MAPK/ERK pathway inhibitor PD98059 (50 µM), and JAK/STAT3 pathway inhibitor AG490 (10 µM), along with CNTF treatment. (A) Quantification of the viability of RGCs after treatment with LY294002, AG490, or PD98059 together with CNTF. The CNTF-enhanced viability of RGCs was decreased by LY284002 and AG490 but not by PD98059. (B) Flow cytometry results evaluating viable RGCs under oxidative stress. The viability of cells was increased by rCNTF but was significantly decreased after AG490 treatment. (C) Western blotting was performed to evaluate β3-tubulin (Tuj 1) expression of RGCs after treatment with LY294002, AG490, or PD98059 together with CNTF. (D) Quantification of Western blot bands shown in C. The expression levels of β3-tubulin relative to the control were significantly decreased by LY284002 and PD98059 but not by AG490. Data in the columns indicate the mean ± SD of three experiments. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ns, not significant. Error bars were not displayed when RGCs were cultured alone in the ATP assay and when RGCs were cultured alone in the Western blot, as they were set as the standard in the experiment.