Journal: Cell reports
Article Title: The Hao-Fountain syndrome protein USP7 regulates neuronal connectivity in the brain via a novel p53-independent ubiquitin signaling pathway
doi: 10.1016/j.celrep.2025.115231
Figure Lengend Snippet: (A) Representative GFP and PSD95 micrographs of dendritic spines (arrowheads) of DIV18 primary cortical neurons with knockdown of Ppil4 or luciferase (Luci). Micrographs of dendritic spines with knockdown of other candidate substrates are shown in . Scale bar, 5 μm. (B–G) Density of all (B–D) and PSD95+ (E–G) spines on apical, basal, and all dendrites of cortical neurons. * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001 by Dunnett’s multiple-comparisons test (compared to Luci). (H) Streptavidin pull-down of HEK293T lysate with overexpression of streptavidin-binding peptide-FLAG (SFB)-tagged USP7 followed by immunoblot analyses. (I) IP of endogenous Ppil4 in HEK293T lysates followed by immunoblot analyses. (J) Reciprocal IP of endogenous USP7 and Ppil4 in mouse brain at age P4, followed by immunoblot analyses. Input lysate with long exposure for clear visualization is shown on the left. (K) TUBE pull-down of MG132-treated neuronal lysate with USP7 loss driven by lentiviral Cre followed by immunoblotting of Ppil4. Densitometric quantification is shown at the bottom. IB, immunoblot; a.u., arbitrary unit. (L and M) In vitro deubiquitination using FLAG-immunoprecipitated Ppil4 from MG132-treated HEK293T cells (L) and densitometric quantification (M) of high-molecular-weight Ppil4 over all Ppil4 signals with 3 biological replicates. ** p < 0.01 by 2-tailed unpaired t test. (N and O) Immunoblot and densitometric quantification ( n = 5 biological replicates) of endogenous Ppil4 in HEK293T cells expressing patient variants of USP7. USP7 C223A is catalytically dead as a positive control. * p < 0.05, ** p < 0.01 by Dunnett’s multiple-comparisons test after repeated-measurement one-way ANOVA. (P) Schematic of the USP7-Ppil4 signaling pathway regulating dendritic spines. Data are presented as mean ± SEM. See also .
Article Snippet: For assessment of the interaction between USP7 and endogenously expressed proteins, an S protein-Streptavidin-binding peptide-FLAG (SFB)-tagged USP7 construct (Addgene plasmid #99393) was transfected into HEK293T cells via PEI transfection.
Techniques: Knockdown, Luciferase, Over Expression, Binding Assay, Western Blot, In Vitro, Immunoprecipitation, High Molecular Weight, Expressing, Positive Control