Effects of the mutations Glu22 to Gln and Ala21 to Gly on the aggregation of a synthetic fragment of the Alzheimer's amyloid β/A4 peptide

Clements, A.; Walsh, Dominic M.; Williams, C. H.

doi:10.1016/0304-3940(93)90129-9

Cited by 81 publications

(60 citation statements)

References 20 publications

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“…ACE experiments using the mutant A␤ E22Q did demonstrate that the mutant peptide assumed a heparin-binding conformation more readily than the wild type. This finding is consistent with previous studies which showed the enhanced ability of A␤ E22Q to stably self-associate in vitro (42)(43)(44)(45). Two additional lines of evidence support ␤-sheet structure as a feature essential for heparin-binding.…”

Section: Discussionsupporting

confidence: 81%

Heparin-binding Properties of the Amyloidogenic Peptides Aβ and Amylin

Watson

Lander

Selkoe

1997

Journal of Biological Chemistry

126

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Aggregation and deposition of the 40 -42-residue amyloid ␤-protein (A␤) are early and necessary neuropathological events in Alzheimer's disease. An understanding of the molecular interactions that trigger these events is important for therapeutic strategies aimed at blocking A␤ plaque formation at the earliest stages. Heparan sulfate proteoglycans may play a fundamental role since they are invariably associated with A␤ and other amyloid deposits at all stages. However, the nature of the A␤-heparan sulfate proteoglycan binding has been difficult to elucidate because of the strong tendency of A␤ to self-aggregate. Affinity co-electrophoresis can measure the binding of proteoglycans or glycosaminoglycans to proteins without altering the physical state of the protein during the assay. We used affinity co-electrophoresis to study the interaction between A␤ and the glycosaminoglycan heparin and found that the aggregation state of A␤ governs its heparin-binding properties: heparin binds to fibrillar but not nonfibrillar A␤. The amyloid binding dye, Congo red, inhibited the interaction in a specific and dose-dependent manner. The "Dutch" mutant A␤ E22Q peptide formed fibrils more readily than wild type A␤ and it also attained a heparin-binding state more readily, but, once formed, mutant and wild type fibrils bound heparin with similar affinities. The heparin-binding ability of aggregated A␤ E22Q was reversible with incubation in a solvent that promotes ␣-helical conformation, further suggesting that conformation of the peptide is important. Studies with another human amyloidogenic protein, amylin, suggested that its heparinbinding properties were also dependent on aggregation state. These results demonstrate the dependence of the A␤-heparin interaction on the conformation and aggregation state of A␤ rather than primary sequence alone, and suggest methods of interfering with this association.

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Section: Discussionsupporting

confidence: 81%

Heparin-binding Properties of the Amyloidogenic Peptides Aβ and Amylin

Watson

Lander

Selkoe

1997

Journal of Biological Chemistry

126

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“…22 In vitro aggregation studies have also shown that A␤ containing E22Q and A21G mutations differ in the kinetics of A␤ fibril formation. E22Q mutant protein accelerates amyloid fibril formation, while the A21G mutant protein polymerizes more slowly than Wt-A␤, 12,[23][24][25] ie, the mutations might act by different pathological mechanisms or share another unknown property that distinguishes them from Wt-A␤. Further study of APP metabolism in vascular cells, such as SMC, transfected with DNA constructs corresponding to the APP693 and APP692 mutations will provide additional insights into the pathogenesis of Alzheimer disease and HCHWA-Dassociated CAA.…”

Section: Discussionmentioning

confidence: 99%

Toxicity of Dutch (E22Q) and Flemish (A21G) Mutant Amyloid β Proteins to Human Cerebral Microvessel and Aortic Smooth Muscle Cells

Wang

Natté

Berliner

et al. 2000

Stroke

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Background and Purpose-Cerebral amyloid angiopathy (CAA) is characterized by the deposition of amyloid ␤ protein (A␤) in cortical and leptomeningeal vessels of patients with Alzheimer's disease and hereditary cerebral hemorrhage with amyloidosis, Dutch type. Smooth muscle cells (SMC) from cerebral microvessels (MV) are of particular interest as a site of A␤-related injury because CAA is much more pronounced in the tunica media of cortical arterioles than meningeal arteries. Patients carrying point mutations at residues 22 (E22Q) and 21 (A21G) of A␤ show severe CAA with various degrees of brain parenchymal A␤ deposition. The purpose of this study was to investigate the effects of 2 mutant E22Q-and A21G-A␤ peptides on MV and aortic SMC. Methods-SMC were isolated from human cerebral MV and aorta. Cell morphology, viability, and proliferation as parameters of A␤ toxicity were investigated after 3 days of peptide treatment by trypan blue exclusion and [ 3 H]thymidine incorporation. Results-E22Q-A␤ induced significant decreased cellular proliferation and viability, as well as obvious degeneration of both MV and aortic SMC. A21G-A␤ and wild-type A␤ did not cause significant toxicity, as judged by cell morphology, viability, or cell proliferation, on either type of SMC. Conclusions-E22Q-A␤ induced greater toxicity in all parameters than A21G-A␤ and wild-type A␤ with respect to both MV and aortic SMC. A21G-A␤ did not show a significant toxic effect on MV and aortic SMC. This differential effect may be linked to cell type-specific processing and metabolism of mutant forms of A␤. Mutations in amyloid precursor protein may lead to CAA by different pathogenetic mechanisms or share an unknown property that distinguishes them from wild-type A␤. (Stroke. 2000;31:534-538.)Key Words: amyloid Ⅲ cerebral circulation Ⅲ microcirculation Ⅲ muscle, smooth Ⅲ mutation C erebral amyloid angiopathy (CAA) is characterized by the deposition of fibrillar amyloid in the media and adventitia of cerebral cortical and meningeal blood vessels. 1,2 Amyloid ␤ protein (A␤) is the main constituent of vascular amyloid in sporadic/Alzheimer disease-associated CAA, Down syndrome, and hereditary cerebral hemorrhage with amyloidosis, Dutch type (HCHWA-D). [3][4][5] The presence of amyloid in the cerebrovascular tunica media is closely associated with degeneration of smooth muscle cells (SMC) in this locus. 1,6 -8 HCHWA-D is an autosomal dominant disease caused by a point mutation at codon 693 of the ␤ amyloid precursor protein (APP). This mutation results in a glutamic acid to glutamine substitution at residue 22 (E22Q) of A␤. HCHWA-D patients consistently develop severe CAA and cerebral hemorrhage but only rarely have significant numbers of senile plaques or neurofibrillary tangles within the See Editorial Comment, page 538 brain. 4,9,10 This makes the clinicopathological phenotype of HCHWA-D unique by comparison with clinicopathological phenotypes associated with other APP mutations. [11][12][13][14][15] This issue is of particular interest when HCHWA-D ...

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“…This mutation is pathogenic since it segregates with the disease (6). Several in vitro studies have shown that Glu 3 Gln substitution yields an A␤ variant that has an abnormal conformation (higher content of ␤-sheet), forms amyloid-like fibrils at a faster rate than wild type A␤, and is toxic to cultured human leptomeningeal smooth muscle cells (7)(8)(9)(10)(11)(12), further supporting its pathogenic role in vivo. Our initial biochemical characterization of amyloid in HCHWA-D revealed that the main constituent of leptomeningeal fibrils was an A␤ species starting at Asp-1 and ending at Val-39 (13).…”

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confidence: 97%

The length of Amyloid-β in Hereditary Cerebral Hemorrhage with Amyloidosis, Dutch Type

Castaño¹,

Prelli²,

Soto

et al. 1996

Journal of Biological Chemistry

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In hereditary cerebral hemorrhage with amyloidosis, Dutch type (HCHWA-D), a genetic variant (E22Q) of amyloid ␤ (A␤) accumulates predominantly in the small vessels of leptomeninges and cerebral cortex, leading to fatal strokes in the fifth or sixth decade of life. A␤ deposition in the neuropil occurs mainly in the form of preamyloid, Congo red negative deposits, while mature neuritic plaques and neurofibrillary tangles, hallmark lesions in Alzheimer's disease (AD), are characteristically absent. A recent hypothesis regarding the pathogenesis of AD states that A␤ extending to residues 42-43 (as opposed to shorter species) can seed amyloid formation and trigger the development of neuritic plaques followed by neuronal damage in AD. We characterized biochemically and immunohistochemically A␤ from three cases of HCHWA-D to determine its length in vascular and parenchymal deposits. Mass spectrometry of formic acid-soluble amyloid, purified by size-exclusion gel chromatography, showed that A␤ 1-40 and its carboxyl-terminal truncated derivatives were the predominant forms in leptomeningeal and cortical vessels. A␤ 1-42 was a minor component in these amyloid extracts. Immunohistochemistry with antibodies S40 and S42, specific for A␤ ending at Val-40 or Ala-42, respectively, were consistent with the biochemical data from vascular amyloid. In addition, parenchymal preamyloid lesions were specifically stained with S42 and were not labeled by S40, in agreement with the pattern reported for AD, Down's syndrome, and aged dogs. Our results suggest that in HCHWA-D the carboxyl-terminal A␤ heterogeneity is due to limited proteolysis in vivo. Moreover, they suggest that A␤ species ending at Ala-42 may not be critical for the seeding of amyloid formation and the development of AD-like neuritic changes.Hereditary cerebral hemorrhage with amyloidosis, Dutch type (HCHWA-D), 1 is an autosomal dominant form of cerebral amyloidosis clinically defined by recurrent strokes and fatal cerebral bleeding in the fifth or sixth decade of life (1). Amyloid deposits are preferentially localized in the walls of small arteries of the leptomeninges and cerebral cortex. Parenchymal deposition is largely in the form of preamyloid lesions or diffuse plaque-like structures that are Congo red-negative and lack the dense amyloid cores commonly present in Alzheimer's disease (AD). Immature or early plaques are occasionally found surrounded by dystrophic neurites, although neurofibrillary tangles are consistently absent (2).Biochemically, HCHWA-D amyloid fibrils are composed of a genetic variant of amyloid ␤ (A␤) of AD and Down's syndrome (3, 4) in which there is a glutamine (Gln) for glutamic acid (Glu) at position 22 due to a missense mutation (cytosine for guanine) at codon 693 of the ␤ precursor protein (␤PP) 770 gene (5). This mutation is pathogenic since it segregates with the disease (6). Several in vitro studies have shown that Glu 3 Gln substitution yields an A␤ variant that has an abnormal conformation (higher content of ␤-sheet), forms amyloid-lik...

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Effects of the mutations Glu22 to Gln and Ala21 to Gly on the aggregation of a synthetic fragment of the Alzheimer's amyloid β/A4 peptide

Cited by 81 publications

References 20 publications

Heparin-binding Properties of the Amyloidogenic Peptides Aβ and Amylin

Heparin-binding Properties of the Amyloidogenic Peptides Aβ and Amylin

Toxicity of Dutch (E22Q) and Flemish (A21G) Mutant Amyloid β Proteins to Human Cerebral Microvessel and Aortic Smooth Muscle Cells

The length of Amyloid-β in Hereditary Cerebral Hemorrhage with Amyloidosis, Dutch Type

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