Fig. 7.
PRR7 promotes the proteasomal degradation of synaptic proteins. a, b Effect of proteasome inhibitors on PRR7-induced removal of PSD-95 clusters. Representative immunofluorescent images of PSD-95 in the dendrites and soma (Lactacystin-treated) from GFP-transfected or HA-PRR7-transfected neurons (a), and quantitation of data (b). Scale bars, 5 μm. Lact lactacystin, MG MG132-treated neurons. n = 17–24. c, d Effect of PRR7 overexpression on the protein levels of major PSD scaffold proteins and poly-ubiquitination (pUb), in the absence (control) or presence of Lact. Representative immunoblots of TCL and purified exosomes from the CS (c) and quantified data for the protein levels in TCL (d). n = 4. e Increased poly-ubiquitination of PSD-95 by PRR7 overexpression. IP immunoprecipitation, Mr relative molecular weights. Two-way ANOVA, post hoc Tukey’s test: F5,230 = 222.3 (b, density), F5,230 = 98.42 (b, intensity), F1,12 = 7.098 (d, PSD-95), and F1,12 = 23.87 (d, K48-pUb). ***P < 0.0001, **P < 0.01, and *P < 0.05. Data are mean ± SEM