Fig. 6: Restoration of protein homeostasis in the subiculum of 5×FAD mice following PV interneuron inhibition, including enhanced GABAergic synapses, amelioration of lysosomal dysfunction, and reduced APP levels.

A Schematic workflow depicting sample acquisition, laser microdissection, and mass spectrometry (MS) analysis (n = 3 per group). B Hierarchical clustering of DEPs related to lysosomes and GABAergic synapses across the four groups. C GO enrichment of DEPs showing opposite trends (fold change >1.2 or < 0.83, p < 0.05), highlighting pathways linked to Aβ metabolism and lysosomal function. D Protein-protein interaction network of DEPs, showing APP and APOE as central hubs. Node size reflects degree, edge width indicates interaction strength. E Quantification of human APP (hAPP) mRNA levels by RT-qPCR showing no significant change after AAV-taCasp3, AAV-hM4Di, or AAV-shPV injections (n = 6 mice/group, unpaired t-test). F, G Western blot analysis of APP in the subiculum following AAV-taCasp3, AAV-hM4Di, or AAV-shPV injections (n = 6 mice/group, unpaired t-test). H, I Representative images of YFP (AAV, green) and APP (red) in the subiculum, showing APP levels in YFP− and YFP+ cells after AAV-hM4Di injection (n = 27–30 cells from 3 mice, two-way ANOVA). J, K Representative images of YFP (AAV, green) and APP (red) in the subiculum, showing APP levels in YFP− and YFP+ cells after AAV-shPV injection (n = 34–35 cells from 3 mice, two-way ANOVA). L, M Immunoprecipitation (IP) of APP followed by Western blot showing total ubiquitination, K48- and K63-linked polyubiquitination of APP in AAV-EYFP and AAV-hM4Di groups after CNO treatment L. Quantification of APP-associated ubiquitin, K48-, and K63-linked ubiquitination levels normalized to IP-APP levels M (n = 3 mice/group, unpaired t-test). All data are represented as mean ± SEM. ns not significant, *p < 0.05, **p < 0.01, ****p < 0.0001.