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Apolipoprotein E impairs amyloid-β fibril elongation and maturation
Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
Visa övriga samt affilieringar
2020 (Engelska)Ingår i: The FEBS Journal, ISSN 1742-464X, E-ISSN 1742-4658, Vol. 287, nr 6, s. 1208-1219Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Alzheimer's disease (AD) is strongly linked to amyloid depositions of the Aβ peptide (Aβ). The lipid-binding protein apolipoprotein E (ApoE) has been found to interfere with Aβ amyloid formation and to exert a strong clinical impact to the pathology of AD. The APOE gene exists in three allelic isoforms represented by APOE ε2, APOE ε3, and APOE ε4. Carriers of the APOE ε4 variant display a gene dose-dependent increased risk of developing the disease. Aβ amyloids are formed via a nucleation-dependent mechanism where free monomers are added onto a nucleus in a template-dependent manner. Using a combination of surface plasmon resonance and thioflavin-T assays, we here show that ApoE can target the process of fibril elongation and that its interference effectively prevents amyloid maturation. We expose a complex equilibrium where the concentration of ApoE, Aβ monomers, and the amount of already formed Aβ fibrils will affect the relative proportion and formation rate of mature amyloids versus alternative assemblies. The result illustrates a mechanism which may affect both the clearance rate of Aβ assemblies in vivo and the population of cytotoxic Aβ assemblies.

Ort, förlag, år, upplaga, sidor
Wiley-Blackwell, 2020. Vol. 287, nr 6, s. 1208-1219
Nyckelord [en]
abeta, amyloid, apolipoprotein E, elongation, surface plasmon resonance
Nationell ämneskategori
Medicinska och farmaceutiska grundvetenskaper Medicinsk bioteknologi (med inriktning mot cellbiologi (inklusive stamcellsbiologi), molekylärbiologi, mikrobiologi, biokemi eller biofarmaci)
Forskningsämne
biologisk kemi
Identifikatorer
URN: urn:nbn:se:umu:diva-165305DOI: 10.1111/febs.15075ISI: 000519662100010PubMedID: 31571352Scopus ID: 2-s2.0-85075677418OAI: oai:DiVA.org:umu-165305DiVA, id: diva2:1371511
Tillgänglig från: 2019-11-20 Skapad: 2019-11-20 Senast uppdaterad: 2023-03-24Bibliografiskt granskad
Ingår i avhandling
1. Mechanistic and morphological studies of Aβ amyloid formation using surface plasmon resonance
Öppna denna publikation i ny flik eller fönster >>Mechanistic and morphological studies of Aβ amyloid formation using surface plasmon resonance
2021 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Alternativ titel[sv]
Mekanistiska och morfologiska studier av Aβ amyloidbildning genom yt-plasmon resonans
Abstract [en]

Alzheimer’s disease (AD) is the most common form of dementia and apart from the individual suffering AD also causes a large economic burden for society. AD is associated with progressive neurodegeneration and atrophy of the brain. Extracellular fibrillar assemblies of the amyloid-β peptide (Aβ) in the brain represent a clinical hallmark of AD and these are today considered to be the initial cause of the disease.  The tissue-damaging properties of Aβ assemblies are, however, linked to their structures. Aβ represents a spectrum of peptides between 38-43 residues that can adopt several structures that differ both concerning their morphology and pathological properties. The mechanisms by which Aβ self-assembles, the binding strength of these structures to Aβ monomers, as well as the cross-interaction between different Aβ variants are today not fully understood. Aβ amyloid formation follows a nucleation-dependent mechanism which implies that a kinetically unfavorable nucleus must form before the formation of an amyloid fibril. The elongation of the fibril then proceeds via a template-dependent mechanism where monomeric peptides are incorporated in a highly ordered manner. Using SPR the template-dependent mode of elongation can be selectively monitored. Here, we have used the technique to probe the binding strength of Aβ fibrils and in paper 1 the role of pH and the intrinsic histidines in the Aβ sequence were investigated. The result shows that the histidines do not contribute to the previously observed increase in fibrillar strength at low pH. In paper 2 we analyzed the cross-templation between the in vivo most common variants of Aβ, represented by Aβ1-40 and Aβ1-42. Within this work, we revealed two intrinsic mechanisms preventing Aβ to adopt the structure of the significantly more pathogenic Aβ1-42 variant. In paper 3 we characterized the effect of apolipoprotein E (ApoE) on Aβ amyloid formation. ApoE is today the strongest genetic linker to the development of AD and a well-known binding partner to Aβ fibrils in vivo. Using SPR we can here show that ApoE can prevent Aβ fibril elongation. Although ApoE effectively impairs fibril formation, preventing elongation may result in alternative assemblies with higher cytotoxic properties which hence may explain its pathological effect. In paper 4 we have linked SPR to scanning electron microscopy (SEM). The work presents a novel and generic approach to simultaneously monitor the kinetic properties of amyloid formation, the binding of ligands, and its morphology. We have here specifically probed the binding properties of ApoE to Aβ fibrils, and in combination with immunogold staining technique revealed its binding pattern. Taken together this work pioneers the use of SPR as a powerful technique to elucidate Aβ amyloid formation and the complex enigma of factors causing AD. 

Ort, förlag, år, upplaga, sidor
Umeå: Umeå University, 2021. s. 57
Serie
Umeå University medical dissertations, ISSN 0346-6612 ; 2155
Nationell ämneskategori
Biokemi och molekylärbiologi Medicin och hälsovetenskap
Forskningsämne
läkemedelskemi; medicinsk biokemi
Identifikatorer
urn:nbn:se:umu:diva-188188 (URN)978-91-7855-658-8 (ISBN)978-91-7855-659-5 (ISBN)
Disputation
Glasburen, KBC, Umeå (Engelska)
Opponent
Handledare
Tillgänglig från: 2021-10-08 Skapad: 2021-10-04 Senast uppdaterad: 2021-10-05Bibliografiskt granskad

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Islam, TohidulGharibyan, Anna L.Brännström, KristofferHedberg, IsabellOlofsson, Anders

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Islam, TohidulGharibyan, Anna L.Brännström, KristofferHedberg, IsabellOlofsson, Anders
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Institutionen för medicinsk kemi och biofysik
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The FEBS Journal
Medicinska och farmaceutiska grundvetenskaperMedicinsk bioteknologi (med inriktning mot cellbiologi (inklusive stamcellsbiologi), molekylärbiologi, mikrobiologi, biokemi eller biofarmaci)

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