Icariin Promotes Lysosomal Degradation of Amyloid-β Precursor Protein via Enhanced Endosome-Lysosome Trafficking to Reduce Amyloid-β Accumulation and Improve Cognitive Function in Alzheimer’s Disease Models

Alzheimer’s disease (AD) represents a devastating global public health crisis, characterized by progressive cognitive decline and memory impairment, with its prevalence and associated disability rates rising exponentially amid global population aging. The pathological hallmarks of AD include the accumulation of amyloid-beta (Aβ) plaques and hyperphosphorylated tau protein tangles, which primarily arise from the aberrant processing of amyloid-β precursor protein (AβPP). Currently, approved therapeutic strategies for AD only provide symptomatic relief, and there is a critical unmet need for effective disease-modifying treatments—particularly those targeting the transport and degradation mechanisms of AβPP, which remain poorly understood and under-explored. This study aims to elucidate the effects of icariin on AβPP subcellular localization and degradation via the lysosomal pathway in both APP/PS1 transgenic mouse model and human-APP695-overexpressing cell line. Combining behavioral assessments with biochemical analyses and confocal microscopy, this study demonstrates that prolonged icariin treatment significantly enhances cognitive function, reduces levels of AβPP, BACE1, and Aβ, and promotes the lysosomal degradation of AβPP by facilitating its transport from early endosomes to lysosomes. The findings reveal that icariin effectively mitigates Aβ generation and cognitive deficits by shortening the residence time of AβPP in early endosomes, thereby filling a key knowledge gap in AβPP metabolism and uncovering a novel regulatory mechanism. These results not only establish icariin as a promising candidate for AD intervention but also propose a new therapeutic avenue targeting AβPP degradation mechanisms, with substantial implications for both basic research and clinical applications in AD treatment. Future investigations should focus on evaluating the translational potential of icariin and characterizing its pharmacological profile to optimize clinical efficacy and safety, addressing the urgent need for disease-modifying therapies for this devastating neurodegenerative disorder. • Icariin alters the co-localization of AβPP with early/late endosome and lysosome markers, not recycling endosome marker. • Icariin redirects AβPP trafficking from early endosome to late endosome or lysosome. • Icariin reduces AβPP amyloidogenic processing and promotes its degradation via the endosomal-lysosomal pathway.