Figure 8.

The overexpression of K136R and 4A Arc mutants enhances reduction of dendritic protrusion width and alterations in dendritic spine morphology. Hippocampal neurons were transfected with SARE-mCherry, wildtype SARE-Arc, SARE-Arc K136R, or SARE-Arc 4A together with β-actin-GFP to visualize cell morphology and stimulated with 10 μM NMDA for 4 h. CH98 (1 μM) was added where indicated. (A) Representative images of GFP fluorescence in dendrite fragments of neurons that were transfected and treated as indicated. Scale bar = 5 μm. (B) Quantitative analysis of dendritic protrusion width. Measurements were averaged per dendrite segment. Two dendrite segments per cell from 20 to 27 cells from three independent cultures were analyzed (6–9 cells per culture). The data are expressed as the mean protrusion width ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001 (one-way ANOVA with Bonferroni correction for multiple comparisons). (C) Cumulative percentage plot of spine width for neurons from (B). Calculations were done for 1700–2000 protrusions per condition. (D) Analysis of dendritic protrusion categories for neurons from (B). Categorization was done for dendrite segment. Two dendrites per cell were analyzed. Data are expressed as mean percentage of protrusions ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001 (one-way ANOVA with Bonferroni correction for multiple comparisons).