The 5xFAD transgenic mouse model is one of the most widely used animal models for Alzheimer's disease (AD) research. This model co-expresses five familial AD mutations—three in the amyloid precursor protein (APP) gene and two in the presenilin 1 (PSEN1) gene—under the neural-specific Thy1 promoter, leading to aggressive amyloid-beta (Aβ) pathology.
The 5xFAD model carries the following familial AD mutations:
| Gene |
Mutation |
Position |
Effect |
| APP |
Swedish (K670N/M671L) |
Aβ domain |
Increased Aβ production |
| APP |
Florida (I716V) |
Aβ domain |
Increased Aβ aggregation |
| APP |
London (V717I) |
Aβ domain |
Increased Aβ aggregation |
| PSEN1 |
M146L |
transmembrane |
Altered γ-secretase activity |
| PSEN1 |
L286V |
transmembrane |
Altered γ-secretase activity |
The "5x" designation refers to the five total mutations, and "FAD" denotes familial Alzheimer's disease.
The model overexpresses APP containing the Swedish, Florida, and London mutations, leading to:
-
Increased Aβ Production: The Swedish double mutation at the β-secretase cleavage site dramatically increases the rate of Aβ generation by facilitating β-secretase (BACE1) access to APP.
-
Altered Aβ Peptide Profile: The mutations shift γ-secretase cleavage toward the more aggregation-prone Aβ42 species.
-
Accelerated Aggregation: The Florida and London mutations enhance Aβ42 aggregation kinetics, promoting rapid plaque formation.
The two PSEN1 mutations (M146L, L286V) affect γ-secretase function:
- Alter the cleavage site specificity, producing more Aβ42 relative to Aβ40
- Lead to earlier onset and more severe pathology compared to single-mutation models
- Plaques appear as early as 2 months of age in the cortex
- By 4-6 months, extensive plaque deposition in the hippocampus and subiculum
- Plaques are dense-core type, with the characteristic amyloid fibrillar structure
- Significant loss of subcortical cholinergic neurons by 9 months
- Progressive neuronal atrophy in affected brain regions
- Neuronal loss precedes or coincides with plaque deposition
- Robust microglial activation surrounding plaques
- Increased astrocyte reactivity (astrogliosis)
- Upregulation of inflammatory cytokines including IL-1β, TNF-α
- Learning and memory deficits observable by 3-4 months
- Deficits in spatial memory (Morris water maze)
- Impaired working memory and executive function
- Motor deficits in later stages
The 5xFAD model is extensively used for:
- Anti-amyloid immunotherapy: Testing monoclonal antibodies (e.g., bananin, lecanemab) and active vaccination approaches
- γ-secretase modulators: Evaluating compounds that shift Aβ production toward shorter, less aggregation-prone peptides
- BACE1 inhibitors: Testing β-secretase inhibitors to reduce Aβ generation
- Aggregation inhibitors: Small molecules designed to prevent Aβ42 oligomerization and fibril formation
Researchers use 5xFAD mice to study:
The model enables validation of:
- PET amyloid tracers (e.g., PiB, florbetapir)
- CSF Aβ42 lowering as a pharmacodynamic marker
- Plasma biomarker candidates
¶ Advantages and Limitations
- Rapid pathology: Plaques appear by 2 months, much faster than other AD models
- Robust phenotype: Clear behavioral deficits and pathological changes
- Well-characterized: Extensive literature and established protocols
- Single Insertion: Single transgene insertion simplifies breeding
- Only amyloid pathology: Lacks prominent tau pathology
- Non-physiological overexpression: Thy1-driven overexpression doesn't reflect endogenous APP regulation
- No neuronal loss mechanism: Neuronal loss appears driven by plaque burden rather than soluble oligomers
- Limited translational relevance: Aggressive amyloid pathology may not fully reflect sporadic AD
- APP/PS1 — Dual transgenic model with APP Swedish + PSEN1 M146L
- 3xTg-AD — Triple transgenic model with both amyloid and tau pathology
- Trem2 knockout crosses — Used to study microglial contributions to amyloid clearance
- Oakley et al., 2006 - 5xFAD: A novel transgenic mouse model of AD with early amyloid deposition
- Mullan et al., 1992 - A novel Swedish APP mutation associated with familial AD
- Bandyopadhyay et al., 2020 - 5xFAD modeling of amyloid pathology in Alzheimer's disease
- Shin et al., 2017 - Characterization of the 5xFAD mouse model for Alzheimer's disease