SUBCELLULAR PROTEOME CHARACTERISATION OF ALZHEIMER'S DISEASE VULNERABLE NEURONS IN APP<SUP>NL-F </SUP>MICE

Selective neuronal vulnerability is a characteristic of many neurodegenerative disorders. In Alzheimer's disease (AD), the first neurons to degenerate are neurons in the entorhinal cortex layer II (ECII). Despite their relevance in the disease’s development and progression, the mechanisms that render ECII neurons selectively susceptible remain unclear.
Transcriptomic studies have outlined the early molecular changes in AD, but mRNA levels alone fail to capture the subcellular processes that drive neurodegeneration on the protein level. We developed an in vivo system for cell-specific and spatially resolved proteomics in ECII neurons. Using TurboID, a novel biotin ligase, we have generated AAVs expressing TurboID fused either to a nuclear export sequence or synaptophysin, to target the somatodendritical and presynaptic compartments of ECII neurons respectively. The expression of these constructs is dependent on a neuron-specific promoter.
In this project, we explore how major AD drivers trigger alterations in the subproteome of ECII neurons. To study how the proteome of ECII neurons is affected by amyloid pathology, we use APP^NL-F knock-in mice, a mouse model of AD that expresses the amyloid precursor protein with two pathogenic mutations, the Swedish (NL) and the Iberian (F). These mice develop amyloid plaques from 6 months old, and cognitive impairment at 18 months. We have characterised the proteome of 3-month-old APP^NL-F mice, before the development of plaques, to detect early changes in ECII neurons.
Results from this study will identify key proteins that contribute to AD pathology, paving the way to discover novel therapeutic targets for the disease.