The Arctic mutation interferes with processing of the amyloid precursor protein

Stenh, Charlotte; Nilsberth, Camilla; Hammarbäck, Josefin; Engvall, Benita; Näslund, Jan; Lannfelt, Lars

doi:10.1097/00001756-200210280-00005

Cited by 48 publications

(45 citation statements)

References 18 publications

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“…The ELISA demonstrated a 30% decrease in A␤1-40 levels and a 70% decrease in A␤1-42 levels in media from APP Arc-Swe cells as compared with APP Swe (Fig 1A, B), similar to earlier results. 14 Remarkably, Western blot (antibody 6E10) of the same samples showed a 40% increase in total A␤ levels in APP Arc-Swe cells as compared with APP Swe (see Fig 1C). Furthermore, brain tissue of young APP Arc-Swe and APP Swe transgenic mice was analyzed with both methods.…”

Section: Discussionmentioning

confidence: 72%

“…However, contrary to other pathogenic AD mutations, ELISA measurements have shown decreased levels of A␤40 and A␤42 in plasma from carriers of the Arctic mutation, 13 as well as in cell culture media from transfected cells. 13,14 Taken together, these findings suggest that the presence of A␤ oligomers may lead to underestimations of A␤ levels measured by ELISA. Here, we investigated if the decreased A␤ ELISA levels seen with the Arctic mutation were caused by reduced ability to measure oligomeric A␤, and if this hypothesis would be more generally applicable by extending also to wild-type A␤ oligomers.…”

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confidence: 79%

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Amyloid‐β oligomers are inefficiently measured by enzyme‐linked immunosorbent assay

Stenh

Englund

Lord

et al. 2005

Annals of Neurology

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Amyloid-beta (Abeta) peptide levels are widely measured by enzyme-linked immunosorbent assay (ELISA) in Alzheimer's disease research. Here, we show that oligomerization of Abeta results in underestimated Abeta ELISA levels. The implications are that comprehensive analysis of soluble Abeta requires either sample pretreatment at denaturing conditions or novel conformation-dependent immunoassays. Our findings might be of relevance for many neurodegenerative disorders in which soluble protein aggregates are the main neurotoxic species.

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Section: Discussionmentioning

confidence: 72%

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confidence: 79%

Amyloid‐β oligomers are inefficiently measured by enzyme‐linked immunosorbent assay

Stenh

Englund

Lord

et al. 2005

Annals of Neurology

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“…Aggregation of A␤1-42 Enhances ApoE4 Potentiation of Lysosomal Leakage-To assess the importance of the aggregation state of A␤1-42 in the potentiation of lysosomal leakage and apoptosis by apoE4 in Neuro-2a cells, we used two mutant forms of A␤1-42: the Arctic mutant, which is prone to aggregation and fibril formation (58,59), and the GM6 mutant, which is highly resistant to multimerization or aggregation (61). In vitro, wild type and Arctic A␤1-42 readily formed high molecular weight forms, whereas GM6 A␤1-42 remained monomeric (Fig.…”

Section: Low Ph Required For Apoe4 Potentiation Of A␤1-42-induced Lysmentioning

confidence: 99%

“…We examined the effect of A␤ aggregation and multimer formation on apoE4 enhancement of lysosomal leakage and apoptosis and will show that multimers are required for the apoE4 effects to be observed. The naturally occurring "Arctic" mutation (E693G), which is associated with early onset AD and enhances aggregation in vitro (58,59) and in vivo (60), and the GM6 mutation (F690S/L705P), which was engineered to resist aggregation (61), were used. Furthermore, we will demonstrate that apoE in the context of A␤1-42 stimulates the appearance of the endosomal/lysosomal pathway in cultured neuronal cells.…”

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confidence: 99%

Reactivity of Apolipoprotein E4 and Amyloid β Peptide

Zhong

Müllendorff

Cheng

et al. 2006

Journal of Biological Chemistry

120

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We previously demonstrated that apolipoprotein E4 (apoE4) potentiates lysosomal leakage and apoptosis induced by amyloid ␤ (A␤) peptide in cultured Neuro-2a cells and hypothesized that the low pH of lysosomes accentuates the conversion of apoE4 to a molten globule, inducing reactive intermediates capable of destabilizing cellular membranes. Here we report that neutralizing lysosomal pH with bafilomycin or NH 4 Cl abolished the apoE4 potentiation of A␤-induced lysosomal leakage and apoptosis in Neuro-2a cells. Consistent with these results, apoE4 at acidic pH bound more avidly to phospholipid vesicles and disrupted them to a greater extent than at pH 7.4. Comparison of "Arctic" mutant A␤, which forms multimers, and GM6 mutant A␤, which remains primarily monomeric, showed that aggregation is essential for apoE4 to potentiate A␤-induced lysosomal leakage and apoptosis. Both apoE4 and A␤1-42 had to be internalized to exert these effects. Blocking the low density lipoprotein receptor-related protein with small interfering RNA abolished the enhanced effects of apoE4 and A␤ on lysosomes and apoptosis. In cultured Neuro-2a cells, A␤1-42 increased lysosome formation to a greater extent in apoE3-or apoE4-transfected cells than in Neo-transfected cells, as shown by immunostaining for lysosome-associated membrane protein 1. Similarly, in transgenic mice expressing apoE and amyloid precursor protein, hippocampal neurons displayed increased numbers of lysosomes. Thus, apoE4 and A␤1-42 may work in concert in neurons to increase lysosome formation while increasing the susceptibility of lysosomal membranes to disruption, release of lysosomal enzymes into the cytosol, and neuronal degeneration. Alzheimer disease (AD)2 is a debilitating neurodegenerative disease. With no effective treatment available, the incidence of AD is likely to increase as the population continues to age. Although in most cases the exact cause is unknown, two proteins have been implicated in its pathogenesis: apolipoprotein E4 (apoE4) and amyloid ␤ (A␤).ApoE has important functions in lipid transport in the blood and in the redistribution of lipids among cells in the brain (1). One of its three common isoforms (2, 3), apoE4, is the major genetic risk factor for AD (4 -6). Moreover, the ⑀4 allele is associated with impaired central nervous system repair after injury and in other neurodegenerative diseases (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22).The A␤ peptide, typically 39 -43 amino acids, is derived from the proteolytic cleavage of the amyloid precursor protein (APP) (23,24). Amyloid plaques, a pathological hallmark of AD, are extracellular deposits of A␤ (25,26). Several findings suggest that apoE, another constituent of plaques, may modulate plaque formation or alter the availability of A␤ for plaque formation. Lipid-free apoE4 avidly complexes with A␤ (27), possibly inducing plaques, whereas lipidated apoE3 facilitates A␤ clearance (28 -32) and may reduce plaque formation. ApoE also modulates the cleavage of APP by ␥-secretase (33).S...

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“…Sequential cleavage of amyloid precursor protein (APP) by ␤ -then ␥ -secretases generates the A ␤ 1-40 and A ␤ peptides that are amyloidogenic and neurotoxic [1] . Cleavage of APP by ␤ -secretase (BACE1), a membrane-bound aspartyl protease, is the first and rate-limiting step in the production of A ␤ [2][3][4] . Consequently, the regulation of BACE1 activity is a key pharmacological target.…”

Section: Introductionmentioning

confidence: 99%

Engineered Heparins: Novel β-Secretase Inhibitors as Potential Alzheimer’s Disease Therapeutics

et al. 2008

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Background: Cleavage of β-amyloid precursor protein (APP) by the protease β-secretase (BACE1) is a key step in β-amyloid peptide processing. We have described a novel role for heparan sulphate polysaccharides in Alzheimer’s disease pathology as naturally occurring inhibitors of β-secretase, suggesting new avenues for discovery of novel drugs for Alzheimer’s disease based on heparins. Objective: To evaluate engineered heparin analogues as novel β-secretase inhibitors in vitro, including modifications to increase bioavailability. Methods: We tested a number of selectively desulphated and chemically modified heparins for their ability to inhibit BACE1 and other proteases in vitro using APP fluorescent resonance energy transfer peptide substrates Results: Several lead compounds have been identified that are effective β-secretase inhibitors, but have negligible activity as anticoagulants or as inhibitors of other aspartyl proteases structurally related to β-secretase. In addition, the compounds studied also give some insight into the structural interaction between β-secretase and heparin, indicating that the structure of the polysaccharide is much more important than charge. Conclusion: We have demonstrated that modifications to increase bioavailability of chemically modified heparins have little effect on their efficacy as β-secretase inhibitors. Therefore, these heparins show promise for development as a novel class of pharmaceuticals that target the underlying pathology of Alzheimer’s disease. We have also found further evidence that it is the structure of the polysaccharide that is important for the interaction with β-secretase, not simply the level of sulphation or charge.

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The Arctic mutation interferes with processing of the amyloid precursor protein

Cited by 48 publications

References 18 publications

Amyloid‐β oligomers are inefficiently measured by enzyme‐linked immunosorbent assay

Amyloid‐β oligomers are inefficiently measured by enzyme‐linked immunosorbent assay

Reactivity of Apolipoprotein E4 and Amyloid β Peptide

Engineered Heparins: Novel β-Secretase Inhibitors as Potential Alzheimer’s Disease Therapeutics

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