Globular amyloid β‐peptide₁₋₄₂ oligomer − a homogenous and stable neuropathological protein in Alzheimer's disease

Abstract

Amyloid b-peptide (Ab) 1)42 oligomers have recently been discussed as intermediate toxic species in Alzheimer's disease (AD) pathology. Here we describe a new and highly stable Ab 1)42 oligomer species which can easily be prepared in vitro and is present in the brains of patients with AD and Ab 1)42 -overproducing transgenic mice. Physicochemical characterization reveals a pure, highly water-soluble globular 60-kDa oligomer which we named 'Ab 1)42 globulomer'. Our data indicate that Ab 1)42 globulomer is a persistent structural entity formed independently of the fibrillar aggregation pathway. It is a potent antigen in mice and rabbits eliciting generation of Ab 1)42 globulomer-specific antibodies that do not cross-react with amyloid precursor protein, Ab 1)40 and Ab 1)42 monomers and Ab fibrils. Ab 1)42 globulomer binds specifically to dendritic processes of neurons but not glia in hippocampal cell cultures and completely blocks long-term potentiation in rat hippocampal slices. Our data suggest that Ab 1)42 globulomer represents a basic pathogenic structural principle also present to a minor extent in previously described oligomer preparations and that its formation is an early pathological event in AD. Selective neutralization of the Ab globulomer structure epitope is expected to have a high potential for treatment of AD. Keywords: Alzheimer's disease, amyloid b-peptide, hippocampal neurons, long-term potentiation, oligomers, polymerization. Abbreviations used: Ab, amyloid b-peptide; AD, Alzheimer's disease; ADDL, amyloid b-peptide-derived diffusible ligand; AFM, atomic force microscopy; APP, amyloid precursor protein; CHO, chinese hamster ovary; CL, cross-linked; CSF, cerebrospinal fluid; DAPI, 4¢,6-Diamidino-2-phenylindole; DIV, days in vitro; EPSPs, excitatory postsynaptic potentials; fEPSP, field excitatory postsynaptic potential; GFAP, glial fibrillary acidic protein; HFIP, 1,1,1,3,3,3 hexafluoro-2-propanol; HFS, high-frequency stimulation; LTP, long-term potentiation; MAP2, microtubule associated protein-2; NBT/BCIP, Nitro blue tetrazolium chloride/5-Bromo-4-chloro-3-indolyl phosphate; PAGE, polyacrylamide gel electrophoresis; PBS, phosphate-buffered saline; PSD-95, postsynaptic density protein 95; RT, room temperature; sAPPa, soluble amyloid precursor protein alpha; SDS, sodium dodecyl sulfate; TBS, Tris-buffered saline; TBST, 0.05% Tween 20 in Tris-buffered saline.

Stabilization of neurotoxic Alzheimer amyloid-β oligomers by protein engineering

“…However, when also considering that disordered regions may remain in the ∼100-kDa β-sheet oligomers, these should contain at least 12 monomer subunits. Hence, a dodecamer stoichiometry of toxic Aβ oligomers that has been favored in other research (4,(28)(29)(30) is consistent with our data.…”

Conformation‐dependent single‐chain variable fragment antibodies specifically recognize beta‐amyloid oligomers

“…Addition of four scFv's blocked any Ab42-induced toxicity at the 0 and 21 h time points. These results are consistent with many previous studies that identified the soluble oligomeric Ab42 forms as the toxic species responsible for neuronal cell death and the inhibition of toxicity by antibodies [3][4][5][6]. Although there are no Ab42 oligomers present in the samples of Ab42 alone and Ab42 with scFv's at 0 time point (Fig.…”

Structure-Selective Anisotropy Assay for Amyloid Beta Oligomers

“…Aβ 1−42 SDSderived oligomers were used for the experiments described in this report. Aβ 1−42 SDS-derived oligomers (globulomers) were prepared according to the general protocol described in, 21 but with some modifications. Aβ 1−42 monomer from Anaspec was redissolved in DMSO (1.0 mg/44 μL/), and sonicated for 5 min.…”