The Psen1‐L166P ‐knock‐in mutation leads to amyloid deposition in human wild‐type amyloid precursor protein YAC transgenic mice

Abstract

Genetically engineered mice have been generated to model cerebral β-amyloidosis, one of the hallmarks of Alzheimer disease (AD) pathology, based on the overexpression of a mutated cDNA of the amyloid-β precursor protein (AβPP) or by knock-in of the murine Aβpp gene alone or with presenilin1 mutations. Here we describe the generation and initial characterization of a new mouse line based on the presence of 2 copies of the human genomic region encoding the wild-type AβPP and the L166P presenilin 1 mutation. At ∼6 mo of age, double-mutant mice develop amyloid pathology, with signs of neuritic dystrophy, intracellular Aβ accumulation, and glial inflammation, an increase in AβPP C-terminal fragments, and an 8 times increase in Aβ42 levels with a 40% decrease in Aβ40 levels, leading to a significant increase (14 times) of Aβ42/Aβ40 ratios, with minimal effects on presenilin or the Notch1 pathway in the brain. We conclude that in mice, neither mutations in AβPP nor overexpression of an AβPP isoform are a prerequisite for Aβ pathology. This model will allow the study of AD pathogenesis and testing of therapeutic strategies in a more relevant environment without experimental artifacts due to the overexpression of a single-mutant AβPP isoform using exogenous promoters.

Chronic anti-murine Aβ immunization preserves odor guided behaviors in an Alzheimer's β-amyloidosis model

“…Instead, Thioflavin-S positive Aβ actually increased in the PCX with chronic m3.2 immunization, despite the improvements in habituation behavior. This finding may reflect the complex dynamics of the interaction between the exogenously expressed hAβ and the endogenous mAβ within the mouse brain during β-amyloid accumulation [31, 43, 44]. However, this is consistent with a more neurotoxic role for non-fibrillar Aβ (as partly measured by 4G8 staining) compared to β-amyloid plaque-associated Aβ in the AD brain [45], suggesting the possibility that reductions in non-fibrillar Aβ in the OB and EC are sufficient to rescue odor habituation behavior, despite persistence of fibrillar Aβ (Thioflavin-S positive) plaques in the PCX.…”

“…Immunization-induced Aβ clearance may operate by several methods, including microglial phagocytosis, the direct disruption of plaques, the clearance of antibody bound Aβ, and the redistribution of brain Aβ to the periphery [43, 44, 46, 47]. In transgenic mouse models of human amyloidosis, the overexpression of hAPP results in the accumulation of hAβ along with the endogenously expressed mAβ [31, 48, 49].…”

Increased Tau Phosphorylation and Tau Truncation, and Decreased Synaptophysin Levels in Mutant BRI2/Tau Transgenic Mice

“…For immunohistochemical and biochemical studies polyclonal antibodies (Abs) were raised in rabbits by injecting a synthetic peptide homologous to residues 23–34 (FNLFLNSQEKHYC) of the ADan amyloid peptide [23] (Abs 1699/1700) and a synthetic peptide homologous to residues 42–54 (GLKAEEAGIGDTC) of tau [27] (Ab d29). Commercial polyclonal Abs against glial fibrillary acidic protein (GFAP) (Dako, Carpinteria, CA) for the detection of astrocytes, an Ab against caspase-3, large subunit and proform (AB1899, Millipore, Temecula, CA), and an Ab against BRI 2 (Itm2b, ab14307, Abcam, Cambridge, MA) were used, as were monoclonal antibodies against synaptophysin (MAB368, Millipore and SY38, Dako), caspase cleaved tau (Tau-C3, MAB5430, Millipore), mouse and human MAPT phosphorylated (p-tau) at Ser202/Thr205 (AT8, Pierce Biotechnology, Rockford, IL), p-tau at Ser212/Thr214 (AT100, Pierce Biotechnology), and beta-actin (AC-15, Sigma, Saint Louis, MO).…”

“…Brains were removed, embedded in paraffin, and sectioned. Sections (8 µm thick) were cut and mounted on poly-l-lysine-coated slides and stained with hematoxylin and eosin [23], [26], [27]. Some sections were stained with Bodian silver staining.…”

Amyloid and intracellular accumulation of BRI2

“…These data highlight the importance of considering the intracellular accumulation of immature mutant BRI 2 pro-protein in the pathobiology of FBD and FDD. In AD, numerous lines of evidence suggest that in addition to Aβ, some of the neurotoxicity associated with AD may be due to the accumulation of C-terminal proteolytic fragments of the amyloid β precursor protein (AβPP), which have been found in patients with the disease and in animal models (Chang and Suh, 2005; Vidal et al, 2012). …”