Nonfibrillar diffuse amyloid deposition due to a gamma(42)-secretase site mutation points to an essential role for N-truncated A beta(42) in Alzheimer's disease.
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Kumar-Singh S, De Jonghe C, Cruts M, Kleinert R, Wang R, Mercken M, De Strooper B, Vanderstichele H, Lofgren A, Vanderhoeven I, Backhovens H, Vanmechelen E, Kroisel PM, Van Broeckhoven C
Nonfibrillar diffuse amyloid deposition due to a gamma(42)-secretase site mutation points to an essential role for N-truncated A beta(42) in Alzheimer's disease.
Hum Mol Genet. 2000 Nov 1;9(18):2589-98.
- PubMed ID
- 11063718 [ View in PubMed]
- Abstract
Amyloidogenic processing of the amyloid precursor protein (APP) with deposition in brain of the 42 amino acid long amyloid beta-peptide (A beta(42)) is considered central to Alzheimer's disease (AD) pathology. However, it is generally believed that nonfibrillar pre-amyloid A beta(42) deposits have to mature in the presence of A beta(40) into fibrillar amyloid plaques to cause neurodegeneration. Here, we describe an aggressive form of AD caused by a novel missense mutation in APP (T714I) directly involving gamma-secretase cleavages of APP. The mutation had the most drastic effect on A beta(42)/A beta(40) ratio in vitro of approximately 11-fold, simultaneously increasing A beta(42) and decreasing A beta(40) secretion, as measured by matrix-assisted laser disorption ionization time-of-flight mass spectrometry. This coincided in brain with deposition of abundant and predominant nonfibrillar pre-amyloid plaques composed primarily of N-truncated A beta(42) in complete absence of A beta(40). These data indicate that N-truncated A beta(42) as diffuse nonfibrillar plaques has an essential but undermined role in AD pathology. Importantly, inhibiting secretion of full-length A beta(42 )by therapeutic targeting of APP processing should not result in secretion of an equally toxic N-truncated A beta(42).