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ABSTRACT: Systematic variation of membrane anchor, spacer and pharmacophore building blocks leads to an optimisation of the inhibitory effect of tripartite structures towards BACE1-induced cleavage of the amyloid precursor protein (APP).
Organic & Biomolecular Chemistry 08/2012; 10(41):8216-35. · 3.70 Impact Factor
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ABSTRACT: In this study, we report a detailed analysis of the different variants of amyloid-β (Aβ) peptides in the brains and the cerebrospinal fluid from APP23 transgenic mice, expressing amyloid precursor protein with the Swedish familial Alzheimer disease mutation, at different ages. Using one- and two-dimensional gel electrophoresis, immunoblotting, and mass spectrometry, we identified the Aβ peptides Aβ(1-40), -(1-42), -(1-39), -(1-38), -(1-37), -(2-40), and -(3-40) as well as minor amounts of pyroglutamate-modified Aβ (Aβ(N3pE)) and endogenous murine Aβ in brains from 24-month-old mice. Chemical modifications of the N-terminal amino group of Aβ were identified that had clearly been introduced during standard experimental procedures. To address this issue, we additionally applied amyloid extraction in ultrapure water. Clear differences between APP23 mice and Alzheimer disease (AD) brain samples were observed in terms of the relative abundance of specific variants of Aβ peptides, such as Aβ(N3pE), Aβ(1-42), and N-terminally truncated Aβ(2/3-42). These differences to human AD amyloid were also noticed in a related mouse line transgenic for human wild type amyloid precursor protein. Taken together, our findings suggest different underlying molecular mechanisms driving the amyloid deposition in transgenic mice and AD patients.
Journal of Biological Chemistry 07/2011; 286(39):33747-58. · 4.77 Impact Factor
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ABSTRACT: In the present study, we report a detailed analysis of the different variants of amyloid-β (Aβ) peptides in the brains and
the cerebrospinal fluid from APP23 transgenic mice, expressing APP with the Swedish familial Alzheimer′s disease mutation,
at different ages. Using one- and two-dimensional gel electrophoresis, immunoblotting and mass spectrometry, we identified
the Aβ peptides Aβ(1-40), -(1-42), -(1-39), -(1-38), -(1-37), -(2-40), -(3-40) as well as minor amounts of pyroglutamate-modified
Aβ (Aβ(N3pE)) and endogenous murine Aβ in brains from 24 months old mice. Chemical modifications of the N-terminal aminogroup
of Aβ were identified that had clearly been introduced during standard experimental procedures. To address this issue, we
additionally applied amyloid extraction in ultrapure water. Clear differences between APP23 mice and Alzheimer′s disease (AD)
brain samples were observed in terms of the relative abundance of specific variants of Aβ peptides, such as Aβ(N3pE), Aβ(1-42)
and N-terminally truncated Aβ(2/3-42). These differences to human AD amyloid were also noticed in a related mouse line transgenic
for human wildtype APP. Taken together, our findings suggest different underlying molecular mechanisms driving the amyloid
deposition in transgenic mice and AD patients.
Journal of Biological Chemistry 07/2011; · 4.77 Impact Factor
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ABSTRACT: Cerebrospinal fluid (CSF) samples from 33 patients with Alzheimer dementia (AD), 21 patients with mild cognitive impairment who converted to AD during followup (MCI-AD), 25 patients with stable mild cognitive impairment (MCI-stable), and 16 nondemented subjects (ND) were analyzed with a chemiluminescence immunoassay to assess the levels of the mitogen-activated protein kinase ERK1/2 (extracellular signal-regulated kinase 1/2). The results were evaluated in relation to total Tau (tTau), phosphorylated Tau (pTau), and beta-amyloid 42 peptide (Aβ42). CSF-ERK1/2 was significantly increased in the AD group as compared to stable MCI patients and the ND group. Western blot analysis of a pooled cerebrospinal fluid sample revealed that both isoforms, ERK1 and ERK2, and low amounts of doubly phosphorylated ERK2 were detectable. As a predictive diagnostic AD biomarker, CSF-ERK1/2 was inferior to tTau, pTau, and Aβ42.
International journal of Alzheimer's disease. 01/2011; 2011:739847.
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ABSTRACT: Covalent coupling of β-secretase inhibitors to a raftophilic lipid anchor via a suitable spacer by using solid-phase peptide synthesis leads to tripartite structures displaying substantially improved inhibition of cellular secretion of the β-amyloid peptide (Aβ). Herein, we describe a series of novel tripartite structures, their full characterization by NMR spectroscopy and mass spectrometry, and the analysis of their biological activity in cell-based assays. The tripartite structure concept is applicable to different pharmacophores, and the potency in terms of β-secretase inhibition can be optimized by adjusting the spacer length to achieve an optimal distance of the inhibitor from the lipid bilayer. A tripartite structure containing a transition-state mimic inhibitor was found to be less potent on Aβ generation from Swedish-mutant amyloid precursor protein (APP) than from the wild-type protein. Moreover, our observations suggest that specific variants of Aβ are generated from wild-type APP but not from Swedish-mutant APP and are resistant to β-secretase inhibition. Efficient inhibition of Aβ secretion by tripartite structures in the absence of appreciable neurotoxicity was confirmed in a primary neuronal cell culture, thus further supporting the concept.
Chemistry 12/2010; 16(48):14412-23. · 5.93 Impact Factor
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ABSTRACT: A method for the efficient decontamination of aluminium oxide ceramic 2-DE focusing trays from β-amyloid peptides (Aβ) is reported. As these contaminations were resistant to the standard cleaning procedures, additional harsh cleaning steps were necessary for their efficient removal. Our observations suggest that specific surface properties affect the degree of adsorption of the Aβ-peptides. "Surface catalysed amyloid aggregation" in the aluminium oxide ceramic trays is proposed as a possible underlying mechanism for the occurrence of proteinase K-resistant forms of Aβ.
Proteomics 10/2010; 10(19):3539-43. · 4.43 Impact Factor
