Fig. 5: GNG5 interacted with PS1 and promoted Aβ42 production.

A Protein–protein interaction network for the potential membrane proteins interacting with GNG5 identified in the IP/MS proteomics. The red triangle represents the hub GNG5. B Western blot detection of GNG5, PS1 and PEN2 (two γ-secretase subunits) in immunoprecipitation extracts from membrane proteins of 293T-GNG5^OE cells. Immunoprecipitation was performed with anti-GNG5 antibody or with anti-PS1 antibody. Immunofluorescence staining with anti-GNG5 (red) and anti-PS1 (green) antibodies in (C) primary hippocampal neurons from newborn rat (day 2) and in (D) eight brain regions related to A score (hippocampus, precentral gyrus, visual cortex, inferior parietal lobule, midbrain, superior temporal gyrus, cerebellum, and basal nucleus) from AD5 (Female, 81y, A3B3C3). Scale bar, 20 µm (C); scale bar, 50 µm (D). E Molecular docking models of γ-secretase-E2012 (PDB: 7D8X) and trimeric GNG5 predicted using ZDOCK. F Quantification of Aβ42 in cellular supernatant obtained from 293T-APP^OE-GNG5^OE cells, pretreated with the γ-secretase inhibitors E2012, Semagacestat, or Avagacestat. G, H Structural models of γ-secretase-C83 complex with homotrimer-GNG5 constructed using Rosetta. GNG5-free PS1–C83 was derived from Cryo-EM structure (PDB: 6IYC). G Enlarged view depicts comparison of positional shift of residues Thr32 and Leu33 between GNG5-bound and GNG5-free PS1–C83. H A close view of the predicted distance between the carboxylate side-chain of Asp257 or Asp385 of PS1 and the C=O group or NH group of Leu33 of C83 in GNG5-free PS1–C83 and GNG5-bound PS1–C83 structures. Residues Thr32, Leu33, Val34 in C83 correspond to Thr48, Leu49, Val50 in C99. Data are presented as the mean ± SD. p values were determined using one-way ANOVA with Turkey post hoc test for multiple groups. **p < 0.01.