Fig. 7.

Spine density and maturation processes are intrinsically linked to the ability of FMRP to be sumoylated. a Representative confocal images of dendrites from transduced WT neurons expressing free GFP, the WT, K88R, K130R, or K88,130R mutant forms of GFP-FMRP for 30 h. Bar, 5 μm. Histograms show the relative proportion of mature and immature spines b and the density of the protrusions d in the indicated conditions shown in a. c Histograms of immature spine length measured from WT neurons expressing the indicated constructs. e Relative protein expression levels of the WT and mutant forms of GFP-FMRP in WT transduced neurons as in a showing an approximate threefold increase in the levels of exogenous GFP-FMRP expression. Data shown in b–d are the mean ± s.e.m. Statistical significance in b–d was determined by a one-way analysis of variance (ANOVA) with a Bonferroni post-test. N = ~3000 spines per condition from four independent experiments. ***p < 0.001; n.s. not significant