The main component of senile plaque amyloid is a 39-to 42-amino-acid segment referred to as beta-amyloid, which is derived from amyloid precursor protein (APP).
The 4-kDa beta-amyloid peptide (Abeta), a principal component of parenchymal amyloid deposits in Alzheimer's disease, is derived from amyloid precursor proteins (APP).
Models of AD include: aged monkeys that show both cognitive/memory deficits and cellular abnormalities (amyloid deposition/cytoskeletal abnormalities of neurons) in cortex and hippocampus; and Tg mice that express mutant human FAD-linked genes (i.e., APP and PS1) and show increased levels of A.42, amyloid deposits, dystrophic neurites, and local responses of astrocytes and microglia.
In this report, we demonstrate that transgenic animals that coexpress a FAD-linked human PS1 variant (A246E) and a chimeric mouse/human APP harboring mutations linked to Swedish FAD kindreds (APP swe) develop numerous amyloid deposits much earlier than age-matched mice expressing APP swe and wild-type Hu PS1 or APP swe alone.
The increased expression and/or abnormal processing of the amyloid precursor protein (APP) is associated with the formation of amyloid plaques and cerebrovascular amyloid deposits, which are one of the major morphological hallmarks of Alzheimer's disease (AD).
The transmembrane domain and a portion of the C-terminus (A beta) of the amyloid precursor protein, are known to form the nucleus of the amyloid plaque.
The amyloid precursor protein (APP) has been associated with Alzheimer's disease (AD) because APP is processed into the beta-peptide that accumulates in amyloid plaques, and APP gene mutations can cause early onset AD.
Here, we describe significant CAA in addition to amyloid plaques, in aging APP/Ld transgenic mice overexpressing the London mutant of human amyloid precursor protein (APP) exclusively in neurons.
The central component of senile amyloid plaques in Alzheimer's disease (AD) is the beta-amyloid peptide (Abeta), derived from proteolytic processing of the amyloid precursor protein (APP).
Transgenic designs emphasizing amyloid precursor protein produced mice that develop amyloid plaques, but neurodegeneration and neurofibrillary tangles failed to form.
To study the effect of amyloid deposits on cell cycle related events in vivo, the expression of cell cycle markers was examined by immunohistochemistry in amyloid precursor protein (APP) transgenic mice (APP23 mice, Swedish double mutation).
A novel magnetic resonance (MR) imaging contrast agent based on a derivative of human amyloid beta (Abeta) peptide, Gd[N-4ab/Q-4ab]Abeta 30, was previously shown to cross the blood-brain barrier (BBB) and bind to amyloid plaques in Alzheimer's disease (AD) transgenic mouse (APP/PS1) brain.
In addition, for animals older than 12 months, we confirmed our previous report that only the two genotypes that form amyloid plaques (APP and PS/APP) have significantly reduced T(2) values compared with NTg controls.
We conclude that the simultaneous presence of human mutated Tau(VLW) and plaque-amyloid (and/or APP(SW)) potentiates and anticipates tau phosphorylation at the 12E8 epitope, intensifying pyramidal neuron immunostaining and tau filament formation in this double-transgenic model.
Furthermore, Alzheimer's amyloid precursor protein, which accumulates within the axonal swellings under pathological conditions, co-accumulated with the PrP-amyloid plaques.
Up-regulated expression of amyloid precursor protein (APP) occurs early in the cascade of events that leads to amyloid plaque formation in the human brain.
Chronic treatment with the α2-adrenoceptor antagonist fluparoxan prevents age-related deficits in spatial working memory in APP×PS1 transgenic mice without altering β-amyloid plaque load or astrocytosis.
Collectively, our results suggest that different pathological mechanisms, namely an intracellular accumulation of APP or extracellular amyloid plaques, may lead to spine abnormalities in young adult APP23 and deltaE9 mice, respectively.