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Properties of defined recombinant oligomeric forms of Aβ1‐42
Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
Linköping University, Department of Neuroscience and Locomotion. Linköping University, Faculty of Health Sciences.
Astra Zeneca R & D, Södertälje, Sweden.
Astra Zeneca R & D, Södertälje, Sweden.
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Oligomers of Aβ1-42 have been identified in human Alzheimer´s disease (AD) patients and in mouse models of AD. These species have attracted intense interest as possible neurological pathogens in AD. In our hands, expression of recombinant human Aβ1-42 in Escherichia coli followed by purification in the presence of cupric ions (CuCl2) afforded recovery of high quantities (>5 mg/L of culture) of well defined trimeric, hexameric, nonameric and dodecameric Aβ1-42. Strong denaturing conditions such as 6 M GuHCI, 8 M urea or boiling in 6.5 M urea supplemented with 2.5 % SDS all failed to separate the oligomers into smaller building blocks implicating that the oligomers are composed of covalently cross-linked Aβ1-42 monomers. Purification in the absence of cupric ions resulted in monomeric Aβ1-42. The Aβ1-42 oligomers were toxic and induced apoptosis when administered to neuroblastoma cells in culture. The described method producing oligomeric Aβ1-42 from a recombinant expression system paves the way for mechanistic studies, structural analysis, drug screening and opens up for vaccine development.

National Category
Natural Sciences
URN: urn:nbn:se:liu:diva-53175OAI: diva2:287407
Available from: 2010-01-18 Created: 2010-01-18 Last updated: 2012-11-15
In thesis
1. Early events in disease associated protein misfolding
Open this publication in new window or tab >>Early events in disease associated protein misfolding
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The scope of this thesis is to unravel some of the mysteries concerning events takingplace early in the amyloid cascade. In vitro studies of early misfolded states ofamyloidogenic proteins are important since the use of recombinant proteins allow us to monitor slight changes in environmental conditions as well as in amino acid composition and thereby illuminate the problem at near atomic resolution.

Human prion protein (HuPrP) (associated with e.g. Creutzfeldt-Jakob disease) andthe Aβ1-42 peptide (associated with Alzheimer’s disease) recombinantly expressed in Escherichia coli have been used as model systems for these studies.

A new protocol for amyloid fibril formation of human prion protein under native conditions was developed. This revealed an unusual pathway of conformational conversion from early formed disordered aggregates that later matured into amyloidfibrils.

The polymorphism 129M/V in HuPrP has a large impact on susceptibility both to sporadic and infectious prion diseases. Some features of this polymorphism havebeen elucidated, employing a mutational study in position 129 (M, A, L, V, P, M, W,E, and K). These investigations have rendered new knowledge about the impact ofsize, charge and β-carbon branching in position 129 upon early intermolecular interactions and the effects of fibril seeding.

Investigations of the interactions between different assembly forms of HuPrP and components of the innate immune system revealed that both native, oligomeric and fibrillar forms of HuPrP activate both the classical and alternative pathways of the Complement System. Most efficient activation is achieved upon binding of oligomeric HuPrP to the complement component C1q.

We have developed a system for recombinant expression of human A,1-42. The monomeric peptides are assembled into various sized soluble oligomers (trimer, hexamer, nonamer, dodecamer). The oligomeric forms were stable in 8 M urea, 6 MGuHCl and SDS suggesting that these were covalently cross-linked. Some mechanistic features in the assembly process have been investigated and we have shown that cupric ions facilitates formation of stable oligomers in our system.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2009. 116 p.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1270
National Category
Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)
urn:nbn:se:liu:diva-52743 (URN)978-91-7393-544-9 (ISBN)
Public defence
2009-11-20, Planck, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Available from: 2010-01-18 Created: 2010-01-12 Last updated: 2012-11-15Bibliographically approved

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Nyström, SofieKågedal, KatarinaHedin, LinneaHammarström, Per
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Department of Physics, Chemistry and BiologyThe Institute of TechnologyDepartment of Neuroscience and LocomotionFaculty of Health Sciences
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