Fig. 2
Disruption of the link between mGluR5 and Homer in WT neurons mimics the Fmr1 KO phenotype. (a) Schematic illustration of the effect of the cell-permeable TAT-mGluR5ct peptide. This peptide disrupts the mGluR5/Homer link, mimicking the situation in Fmr1 KO neurons. (b) Representative trajectories of single surface mGluR5-QD in WT and Fmr1 KO neurons treated with TAT-mGluR5ct and its mutated TAT-mGluR5mu control peptide (both peptides 5 µM, 1 h). The synaptic sites are represented by the green areas. Scale bar = 1 μm. (c) Normalized cumulative distribution of the instantaneous diffusion coefficient of mGluR5-QDs in the synaptic area of WT and Fmr1 KO neurons treated with TAT-mGluR5mu and TAT-mGluR5ct. The lateral diffusion rate of mGluR5-QDs in WT neurons treated with TAT-mGluR5ct peptide is comparable to that in Fmr1 KO neurons under basal conditions (WT, 0.016 ± 0.002 µm2/s, n = 636 trajectories from 12 dendritic fields of 3 cultures; WT TAT-mGluR5mu, 0.016 ± 0.002 µm2/s, n = 1798 trajectories from 12 dendritic fields of 3 cultures; WT TAT-mGluR5ct, 0.026 ± 0.002 µm2/s, n = 1444 trajectories from 19 dendritic fields of 3 cultures; Fmr1 KO, 0.025 ± 0.002 µm2/s, n = 797 trajectories from 16 dendritic fields of 3 cultures; Fmr1 KO TAT-mGluR5mu, 0.023 ± 0.001 µm2/s, n = 1419 trajectories from 13 dendritic fields of 3 cultures; Fmr1 KO TAT-mGluR5ct, 0.024 ± 0.002 µm2/s, n = 489 trajectories from 9 dendritic fields of 3 cultures; WT TAT-mGluR5mu vs. WT TAT-mGluR5ct ***P < 0.001 by Kruskal–Wallis test with Dunn’s multiple comparison test; WT TAT-mGluR5ct vs. Fmr1 KO P > 0.999 by Kruskal–Wallis test with Dunn’s multiple comparison test). (d) Cumulative frequency distribution of the instantaneous diffusion coefficient of mGluR5-QDs within the synaptic area of WT and Fmr1 KO neurons treated with TAT-mGluR5mu and TAT-mGluR5ct (***P < 0.001 by Kolmogorov–Smirnov test. For statistical analysis each condition was separately compared to WT TAT-mGluR5mu)
