N-truncated Aβ4–x peptides in sporadic Alzheimer’s disease cases and transgenic Alzheimer mouse models

Abstract

BackgroundThe deposition of neurotoxic amyloid-β (Aβ) peptides in plaques in the brain parenchyma and in cerebral blood vessels is considered to be a key event in Alzheimer’s disease (AD) pathogenesis. Although the presence and impact of full-length Aβ peptides such as Aβ1–40 and Aβ1–42 have been analyzed extensively, the deposition of N-terminally truncated Aβ peptide species has received much less attention, largely because of the lack of specific antibodies.MethodsThis paper describes the generation and characterization of novel antibodies selective for Aβ4–x peptides and provides immunohistochemical evidence of Aβ4–x in the human brain and its distribution in the APP/PS1KI and 5XFAD transgenic mouse models.ResultsThe Aβ4–x staining pattern was restricted mainly to amyloid plaque cores and cerebral amyloid angiopathy in AD and Down syndrome cases and in both AD mouse models. In contrast, diffuse amyloid deposits were largely negative for Aβ4–x immunoreactivity. No overt intraneuronal staining was observed.ConclusionsThe findings of this study are consistent with previous reports demonstrating a high aggregation propensity of Aβ4–x peptides and suggest an important role of these N-truncated Aβ species in the process of amyloidogenesis and plaque core formation.Electronic supplementary materialThe online version of this article (doi:10.1186/s13195-017-0309-z) contains supplementary material, which is available to authorized users.

The metalloprotease ADAMTS4 generates N-truncated Aβ4–x species and marks oligodendrocytes as a source of amyloidogenic peptides in Alzheimer’s disease

“…3b, d). As demonstrated in our previous study [79], the levels of the N-truncated Aβ4-40 peptides were low compared to full-length Aβ peptides in 5xFAD mice. In the SDS-soluble brain fractions of 12-month-old animals, Aβ4-40 levels were approximately 70-fold and 1500-fold lower than Aβ1-40 and Aβ1-42 levels (Fig.…”

“…While Aβ peptides truncated at various N-terminal residues have been detected in brain tissue and cerebrospinal fluid samples of AD patients [6,40], subsequent studies have largely confirmed that Aβ4-42 and peptides with a pyroglutamate modification at position 3 (AβpE3-42) are particularly abundant [45,50,51,58,59,68]. Recently, two studies reported novel Aβ4-x-specific antibodies and the consistent finding that in the brains of AD patients and mouse models Aβ4-x peptides were largely confined to amyloid plaque cores, which are composed of the most insoluble, fibrillar Aβ peptides in β-sheet conformation [11,79]. In accordance, biophysical studies have demonstrated that Aβ4-x peptides rapidly assembled into soluble oligomers and fibrillar, high-molecular-weight aggregates [7,11,56].…”

“…127003). Anti-Aβ antibodies: IC16 (mouse mAb that preferentially detects Aβ peptides starting with Asp in position 1) [2]; 029-2 (guinea pig pAb that exclusively detects Aβ4-x with Phe in position 4, 1:500 immunohistochemistry) [79]; BAP-24 (Aβ40 C-terminus-specific mouse mAb) [24]; BAP-29 (Aβ38 C-terminus-specific mouse mAb) [24]; BAP-15 (Aβ42 C-terminus-specific mouse mAb) [8,24]…”

“…Aβ levels in brain extracts and conditioned tissue culture supernatants were determined using specific sandwich enzyme-linked immunosorbent assays (ELISA) as described [29,79]. Standard curves were generated with synthetic Aβ peptides (JPT).…”

“…Due to the differential ionization properties of similar peptides, the quantitative analysis of MALDI-TOF measurements is limited and the peak heights in the mass spectra do not correspond to the abundance of individual peptides [9]. To obtain quantitative data and to confirm these results with an independent method, culture supernatants were analyzed with a sandwich ELISA that combined an Aβ40 C-terminus-specific antibody with the polyclonal antibody 029-2, which exclusively detects Aβ4-x peptides with Phe at position 4, as described [79]. Measurements revealed around 2 ng/ml of Aβ4-40 peptides in culture supernatants after induction of ADAMTS4 expression, while non-induced control cells showed no background signal (Fig.…”