Dynamic changes in lysosome-related pathways in APP/PS1 mice with aging.

Senile plaque, composed of amyloid β protein (Aβ) aggregates, is a critical pathological feature in Alzheimer's disease (AD), leading to cognitive dysfunction. However, how Aβ aggregates exert age-dependent toxicity and temporal cognitive dysfunction in APP/PS1 mice remains incompletely understood. In this study, we investigated AD pathogenesis and dynamic alterations in lysosomal pathways within the hippocampus of age-gradient male mice using transcriptome sequencing, molecular biology assays, and histopathological analyses. We observed high levels of β-amyloid precursor protein (APP) protein expression in the hippocampus at an early stage and age-dependent Aβ deposition. Transcriptome sequencing revealed the enrichment of differential genes related to the lysosome pathway. Furthermore, the protein expression of ATP6V0d2 and CTSD associated with lysosomal functions exhibited dynamic changes with age, increasing in the early stage and decreasing later. Similar age-dependent patterns were observed for the endosome function, autophagy pathway, and SGK1/FOXO3a pathway. Nissl and Golgi staining in the hippocampal region showed age-dependent neuronal loss and synaptic damage, respectively. These findings clearly define the age-gradient changes in the autophagy-lysosome system, the endosome/lysosome system, and the SGK1/FOXO3a pathway in the hippocampus of APP/PS1 mice, providing new perspectives and clues for understanding the possible mechanisms of AD, especially the transition from compensatory to decompensated state.