Hong Kong University of Science and Technology, Hong Kong
Abstract: Alzheimer’s disease (AD) affects over 55 million people worldwide. Familial AD, which accounts for approximately 1–5% of all AD cases, is characterized by early-onset cognitive decline, accelerated brain atrophy, and rapid disease progression compared to AD. Familial AD is primarily caused by single pathogenic mutations in 1 of 3 genes: APP (amyloid precursor protein), PSEN1 (presenilin 1), and PSEN2 (presenilin 2). The APP-V717I mutation is one of the most common APP mutations worldwide. However, the mechanisms by which this mutation induces neurodegeneration remain unclear. Here, we utilized patient-derived induced pluripotent stem cells (iPSCs) carrying the APP-V717I mutation and differentiated them into cortical neurons as a model to investigate the underlying mechanism. Compared to control, conditioned media from these iPSC-derived patient neurons has elevated levels of Aβ42 level and Aβ42/40 ratio as well as a lower sAPPα/β ratio. In addition, these neurons exhibited alteration of gene expression linked to cell stress and stress response pathways. Furthermore, neurons carrying the APP-V717I mutation exhibited an increase in reactive oxygen species after induction, suggesting impairment of anti-oxidative stress function. We then used the CRISPR/Cas9 gene editing system to disrupt the APP-V717I mutation, which rescued the alterations in APP processing, including Aβ42 level, Aβ42/40 ratio, and sAPPα/β ratio. Moreover, we noted a reversal of stress-related transcriptomic changes and restoration of anti-oxidative stress function in neurons differentiated from genome-edited iPSC. These findings elucidate how the APP-V717I mutation disrupts APP processing and exacerbates neuronal stress. The rescue of molecular and functional deficits through CRISPR editing underscores its potential as a targeted therapeutic strategy for familial AD.
