Facilitation of AMPA Receptor Synaptic Delivery as a Molecular Mechanism for Cognitive Enhancement
(A) Cartoon structure of the double fibronectin module (FN1+FN2) of human NCAM (Protein Data Bank number 2VKW). The FGL sequence is shown in red with the two glutamine residues critical for the binding to the FGF-receptor highlighted in magenta. (B) Top: Representative immunoblot showing the in vitro phosphorylation of FGFR1 after stimulation of Trex293 cells that express Strep-tagged human FGFR1 with different concentrations of FGL and 10 ng/ml FGF1 (positive control) for 20 min. Bottom: Quantification of FGFR1 phosphorylation by FGL was performed by densitometric analysis of band intensity from four independent experiments similar to the one shown in the upper panel. (C) Phosphorylation of FGFR1 and TrkB was examined from hippocampal homogenates with an enzyme-linked immunosorbent assay (ELISA) 1 h after FGL subcutaneous injection. N, number of animals. Results are expressed as percentage ± SEM, with untreated controls set at 0%. (D–F) Phosphorylation of PLCγ (D), Shc (E), and FRS2 (F) in vitro was examined by Western blot, as described in Figure 1B. Treatment with FGF1 served as the positive control. Results from four independent experiments are expressed as a percentage ± SEM, with untreated controls set at 100%. *p<0.05, **p<0.01, ***p<0.001 compared with controls. Statistics were carried out according to the t test.