Figure 7.

Neuroprotective effect of PDGF-CC is achieved by regulating GSK3β phosphorylation. (A) PDGF-CC protein treatment activated Akt significantly in cultured RGC5 cells. (B) In a phospho-MAPK array screening assay, PDGF-CC treatment increased GSK3β Ser⁹ phosphorylation specifically (top, arrows) in HUVSMCs, whereas the phosphorylation of the other molecules remained unchanged. (C and D) In cultured PC12 (C) and RGC5 (D) neuronal cells, PDGF-CC protein treatment increased GSK3β Ser⁹ phosphorylation and decreased GSK3β Tyr²¹⁶ phosphorylation, respectively, in a time-dependent manner. Black lines indicate that intervening lanes have been spliced out. (E and F) PDGF-CC protein treatment increased GSK3β Ser⁹ phosphorylation (E) and decreased GSK3β Tyr²¹⁶ phosphorylation (F), respectively, in the retina in vivo. (G) PDGF-CC neutralizing antibody treatment increased GSK3β Tyr²¹⁶ phosphorylation in the retina in vivo. (H) PDGF-CC protein treatment inhibited GSK3β expression in different types of neuronal tissues/cells, including SN, retina (normal or with ONC/NMDA injury), RGC5 cells, and brain cortex with MCAO as measured by real-time PCR. (I) PDGF-CC protein treatment protected RGC5 cells from H₂O₂-induced cell death in the control cells and cells expressing wild-type GSK3β (GSK3β-WT). The protective effect of PDGF-CC diminished in the RGC5 cells expressing mutant GSK3β, in which Ser⁹ was mutated to alanine (GSK3β-A9). **, P < 0.01; ***, P < 0.001. The data are represented as means ± SEM of the number of determinations. Experiments, except B, were repeated independently twice with similar results. Representative images (A and C–G) and experiments are shown. nab, neutralizing antibody.