Preferential adsorption, internalization and resistance to degradation of the major isoform of the Alzheimer's amyloid peptide, Aβ1–42, in differentiated PC12 cells

Burdick, Debra; Kosmoski, Joseph V.; Knauer, Mary F.; Glabe, Charles G.

doi:10.1016/s0006-8993(96)01262-0

Cited by 113 publications

(109 citation statements)

References 6 publications

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“…It is also possible that APPV717I fibroblasts did not internalize amyloid aggregates unless cellular blebbing was present. Our results, however, are consistent with other previous studies showing intracellular accumulation of A␤ 1-40 and A␤ 1-42 in granular deposits in late endosomes and lysosomes of human fibroblasts, PC12, monocytic and neuroblastoma cell lines [8,37,56,72]. It is increasingly recognized that disruption of the integrity of cell membranes by small prefibrillar assemblies probing into the membrane bilayer is a primary step in the induction of oxidative damage and after cell death [6,23,36,43,57,61]; the early appearance of amyloid aggregates in the cytoplasm of fibroblasts therefore suggests that these species are the main source of oxidative stress for cells.…”

Section: Discussionsupporting

confidence: 94%

Increased susceptibility to amyloid toxicity in familial Alzheimer's fibroblasts

Cecchi

Fiorillo

Baglioni

et al. 2007

Neurobiology of Aging

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Much experimental evidence suggests that an imbalance in cellular redox status is a major factor in the pathogenesis of Alzheimer's disease (AD). Our previous data showed a marked increase in membrane lipoperoxidation in primary fibroblasts from familial AD (FAD) patients. In the present study, we demonstrate that when oligomeric structures of A␤ 1-40 and A␤ 1-42 are added to the culture media, they accumulate quicker near the plasma membrane, and are internalized faster and mostly in APPV717I fibroblasts than in age-matched healthy cells; this results in an earlier and sharper increase in the production of reactive oxygen species (ROS). Higher ROS production leads in turn to an increase in membrane oxidative-injury and significant impairment of cellular antioxidant capacity, giving rise to apoptotic cascade activation and finally to a necrotic outcome. In contrast, healthy fibroblasts appear more resistant to amyloid oxidative-attack, possibly as a result of their plasma membrane integrity and powerful antioxidant capacity. Our data are consistent with increasing evidence that prefibrillar aggregates, compared to mature fibrils, are likely the more toxic species of the peptides. These findings provide compelling evidence that cells bearing increased membrane lipoperoxidation are more susceptible to aggregate toxicity as a result of their reduced ability to counteract amyloid oligomeric attack.

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Section: Discussionsupporting

confidence: 94%

Increased susceptibility to amyloid toxicity in familial Alzheimer's fibroblasts

Cecchi

Fiorillo

Baglioni

et al. 2007

Neurobiology of Aging

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Section: Neurotoxic Activity Of All-d-␤-amyloid 7434supporting

confidence: 65%

“…Finally, the cell surface contains numerous proteins with Ig superfamily homology with extensive ␤-sheet content, which include receptors (55) and cell adhesion molecules (i.e. NCAM and N-cadherin) (56), and in several reports, the cell surface appears to be able to actually nucleate A␤ assembly (40,57,58), which is also consistent with the model (49).The fact that the all-D analogs of A␤ retain bioactivity may present new avenues for therapeutic intervention by allowing the D-enantiomers of inhibitory peptides to be utilized. An approach similar to this has recently been used to identify an all-D-amino acid opioid peptide with analgesic activity capable of crossing the blood brain barrier using a synthetic combinatorial library made up of D-amino acid hexapeptides (59).…”

mentioning

confidence: 99%

All-D-Enantiomers of β-Amyloid Exhibit Similar Biological Properties to All-L-β-Amyloids

Cribbs

Pike²,

Weinstein³

et al. 1997

Journal of Biological Chemistry

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The amyloidogenic peptide ␤-amyloid has previously been shown to bind to neurons in the form of fibrillar clusters on the cell surface, which induces neurodegeneration and activates a program of cell death characteristic of apoptosis. To further investigate the mechanism of A␤ neurotoxicity, we synthesized the all-D-and all-Lstereoisomers of the neurotoxic truncated form of A␤ (A␤ [25][26][27][28][29][30][31][32][33][34][35] ) and the full-length peptide (A␤ 1-42 ) and compared their physical and biological properties. We report that the purified peptides exhibit nearly identical structural and assembly characteristics as assessed by high performance liquid chromatography, electron microscopy, circular dichroism, and sedimentation analysis. In addition, both enantiomers induce similar levels of toxicity in cultured hippocampal neurons. These data suggest that the neurotoxic actions of A␤ result not from stereoisomer-specific ligand-receptor interactions but rather from A␤ cellular interactions in which fibril features of the amyloidogenic peptide are a critical feature. The promiscuous nature of these ␤-sheet-containing fibrils suggests that the accumulation of amyloidogenic peptides in vivo as extracellular deposits represents a site of bioactive peptides with the ability to provide inappropriate signals to cells leading to cellular degeneration and disease.Alzheimer's disease (AD), 1 vascular dementia, and hereditary cerebral hemorrhage with the Dutch type are diseases that share an invariant pathological feature, the accumulation of an amyloidogenic peptide into insoluble fibrillar extracellular deposits. In all three cases, the major component of the extracellular debris is the ␤-amyloid peptide (A␤) that is derived from the proteolytic processing of the large membraneanchored amyloid precursor protein (APP) encoded by a single gene located on chromosome 21 (1). However, the biological significance of these amyloid deposits has been extensively debated as to whether they are a causative factor of each disease or merely a metabolically inert end product lacking in biological activity. Evidence in support of a causative role for A␤ in neuropathology comes from genetic analysis of the APP gene where several autosomal dominant mutations have been linked with AD and hereditary cerebral hemorrhage with the Dutch type (2, 3). In a recent in vitro study, the ␤-APP 717 mutation consistently caused a significant increase in the percentage of the longer and more amyloidogenic A␤ 1-42 over the shorter A␤ 1-40 (4). Incorporation of this same mutation into a transgenic mouse model yields A␤ deposition and neuropathology that closely parallels that observed in AD (5). Additional in vivo evidence suggesting that the A␤ peptide itself may be biologically active comes from a transgenic model overexpressing A␤ , in which A␤ transgene expression was detected in a variety of peripheral tissues but histopathological changes were restricted to the brain. Moreover, the neurodegeneration was largely limited to the cerebral cortex, ...

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“…But intracellular A␤42 has been shown to be degraded more slowly than intracellular A␤40, too slowly to contribute to the experiments here (33). Furthermore, A␤ is found in cultured cells at much lower levels than secreted A␤ (29, 34 -36), suggesting that A␤ is rapidly secreted upon generation and, hence, that its intracellular degradation is unlikely to contribute to its turnover.…”

Section: Discussionmentioning

confidence: 73%

Rank-Order of Potencies for Inhibition of the Secretion of Aβ40 and Aβ42 Suggests That Both Are Generated by a Single γ-Secretase

Durkin¹,

Murthy²,

Husten³

et al. 1999

Journal of Biological Chemistry

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The Alzheimer's disease amyloid peptide A␤ has a heterogeneous COOH terminus, as variants 40 and 42 residues long are found in neuritic plaques and are secreted constitutively by cultured cells. The proteolytic activity that liberates the A␤ COOH terminus from the ␤-amyloid precursor protein is called ␥-secretase. It could be one protease with dual specificity or two distinct enzymes. By using enzyme-linked immunosorbent assays selective for A␤40 or A␤42, we have measured A␤ secretion by a HeLa cell line, and we have examined the dose responses for a panel of five structurally diverse ␥-secretase inhibitors. The inhibitors lowered A␤ and p3 secretion and increased levels of the COOH-terminal 99-residue ␤-amyloid precursor protein derivative that is the precursor for A␤ but did not alter secretion of ␤-amyloid precursor protein derivatives generated by other secretases, indicating that the inhibitors blocked the ␥-secretase processing step. The dose-dependent inhibition of A␤42 was unusual, as the compounds elevated A␤42 secretion at sub-inhibitory doses and then inhibited secretion at higher doses. A compound was identified that elevated A␤42 secretion at a low concentration without inhibiting A␤42 or A␤40 at high concentrations, demonstrating that these phenomena are separable pharmacologically. Using either of two methods, IC 50 values for inhibition of A␤42 and A␤40 were found to have the same rank-order and fall on a trend line with near-unit slope. These results favor the hypothesis that A␤ variants ending at residue 40 or 42 are generated by a single ␥-secretase.A hallmark feature of the neuropathology of Alzheimer's disease is the abundant deposition of amyloid into neuritic and diffuse plaques in the brain parenchyma. The predominant core constituent of amyloid plaques is a 40-to 42-residue amyloid peptide, A␤.1 A␤ is generated from the ␤-amyloid precursor protein (APP) by two sequential proteolytic cleavages. First, ␤-secretase activity liberates the NH 2 terminus of A␤, generating a 99-residue COOH-terminal APP fragment (C99). Second, ␥-secretase activity cleaves C99 to liberate the A␤ COOH terminus. APP is also processed in a nonamyloidogenic manner, being cleaved within the A␤ domain by an activity termed ␣-secretase. The terms ␣-, ␤-, and ␥-secretase are conceptual terms for proteases that are not yet definitively identified (reviewed in Refs. 1-3).The A␤ peptide is a constitutive secretory product of a variety of neuronal and non-neuronal cells, in which multiple NH 2 -and COOH-terminal cleavages generate several A␤ species. The most prevalent secreted forms of A␤ appear identical to neuritic plaque core amyloid A␤ and terminate either at residue 40 or 42 (4, 5). Although A␤40 variants are the predominant component of soluble A␤ extracted from brain and secreted by cultured cells, A␤42 forms are the predominant constituents of neuritic plaques (6 -9). In vitro, forms of A␤ that terminate at residue 42 form fibril faster than forms of A␤ that terminate at residue 40, by orders of magnitude (10). Mut...

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Preferential adsorption, internalization and resistance to degradation of the major isoform of the Alzheimer's amyloid peptide, Aβ1–42, in differentiated PC12 cells

Cited by 113 publications

References 6 publications

Increased susceptibility to amyloid toxicity in familial Alzheimer's fibroblasts

Increased susceptibility to amyloid toxicity in familial Alzheimer's fibroblasts

All-D-Enantiomers of β-Amyloid Exhibit Similar Biological Properties to All-L-β-Amyloids

Rank-Order of Potencies for Inhibition of the Secretion of Aβ40 and Aβ42 Suggests That Both Are Generated by a Single γ-Secretase

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