Sequence-dependent Internalization of Aggregating Peptides

Couceiro, José R.; Gallardo, Rodrigo; Smet, Frederik De; Baets, Greet De; Baatsen, Pieter; Annaert, Wim; Roose, Kenny; Saelens, Xavier; Schymkowitz, Joost; Rousseau, Frédéric

doi:10.1074/jbc.m114.586636

Cited by 22 publications

(31 citation statements)

References 71 publications

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“…This supports the view that toxicity of amyloidogenic proteins is tightly linked to assembly size and structure. It has previously been reported that the uptake of aggregating amyloid proteins is sequence specific , and the cellular response to these proteins is thought to be highly dependent on aggregation propensity, size and charge. As the sequences of both control peptides have led to a higher propensity to aggregate than wild‐type Aβ1‐42, confirmed by structural characterisation presented above, the reported mechanisms of internalisation, which include dynamin‐mediated endocytosis , may not be possible with the control peptides.…”

Section: Resultsmentioning

confidence: 99%

Amyloidogenicity and toxicity of the reverse and scrambled variants of amyloid‐β 1‐42

et al. 2017

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β‐amyloid 1‐42 (Aβ1‐42) is a self‐assembling peptide that goes through many conformational and morphological changes before forming the fibrils that are deposited in extracellular plaques characteristic of Alzheimer's disease. The link between Aβ1‐42 structure and toxicity is of major interest, in particular, the neurotoxic potential of oligomeric species. Many studies utilise reversed (Aβ42‐1) and scrambled (AβS) forms of amyloid‐β as control peptides. Here, using circular dichroism, thioflavin T fluorescence and transmission electron microscopy, we reveal that both control peptides self‐assemble to form fibres within 24 h. However, oligomeric Aβ reduces cell survival of hippocampal neurons, while Aβ42‐1 and Aβs have reduced effect on cellular health, which may arise from their ability to assemble rapidly to form protofibrils and fibrils.

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Section: Resultsmentioning

confidence: 99%

Amyloidogenicity and toxicity of the reverse and scrambled variants of amyloid‐β 1‐42

et al. 2017

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“…Other pathways for the internalization of amyloidogenic proteins have been discussed. Synthetic peptide aggregates of sizes Ͻ500 nm were taken up into HEK cells by nonspecific endocytosis, whereas larger aggregates were internalized by a mechanism similar to phagocytosis (35). Tau aggregates can be internalized via micropinocytosis, mediated by glycosaminoglycans (36).…”

Section: Discussionmentioning

confidence: 99%

Amyloid-β(1–42) Aggregation Initiates Its Cellular Uptake and Cytotoxicity

Jin

Kedia

Illes‐Toth

et al. 2016

Journal of Biological Chemistry

102

116

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The accumulation of amyloid ␤ peptide(1-42) (A␤(1-42)) in extracellular plaques is one of the pathological hallmarks of Alzheimer disease (AD). Several studies have suggested that cellular reuptake of A␤(1-42) may be a crucial step in its cytotoxicity, but the uptake mechanism is not yet understood. A␤ may be present in an aggregated form prior to cellular uptake. Alternatively, monomeric peptide may enter the endocytic pathway and conditions in the endocytic compartments may induce the aggregation process. Our study aims to answer the question whether aggregate formation is a prerequisite or a consequence of A␤ endocytosis. We visualized aggregate formation of fluorescently labeled A␤(1-42) and tracked its internalization by human neuroblastoma cells and neurons. ␤-Sheet-rich A␤(1-42) aggregates entered the cells at low nanomolar concentration of A␤(1-42). In contrast, monomer uptake faced a concentration threshold and occurred only at concentrations and time scales that allowed A␤(1-42) aggregates to form. By uncoupling membrane binding from internalization, we found that A␤(1-42) monomers bound rapidly to the plasma membrane and formed aggregates there. These structures were subsequently taken up and accumulated in endocytic vesicles. This process correlated with metabolic inhibition. Our data therefore imply that the formation of ␤-sheet-rich aggregates is a prerequisite for A␤(1-42) uptake and cytotoxicity.One of the pathological hallmarks of Alzheimer disease (AD) 2 is the presence of extracellular plaques composed mainly of 42-amino acid amyloid ␤ peptide (A␤(1-42)) (1). The small hydrophobic A␤(1-42) peptide, which is generated by proteolytic cleavage of the amyloid precursor protein, is released as a monomer from the plasma membrane into extracellular space, and tends to aggregate spontaneously into oligomeric, protofibrillar, and fibrillar assemblies (2-4). Oligomeric species of A␤(1-42) are tightly linked to AD pathogenesis and are presumed to be the cause of neuronal damage (5). Several studies have suggested that the reuptake of extracellular A␤(1-42) into neurons may lead to the formation of intracellular aggregates, resulting in neuronal damage and neurotoxicity (6 -8). Endocytosis of misfolded proteins has also been observed in cell models of the tau protein, ␣-synuclein and huntingtin (9, 10), and recent evidence suggests that it may be the initial step in the replication of the misfolded protein structures by prion mechanisms (10 -14). Several possible endocytic pathways, such as macropinocytosis and receptor-mediated endocytosis, have been discussed for A␤ and other misfolded protein aggregates (15-19). However, our understanding of the connection between aggregation and cytotoxicity is still limited. It has not been conclusively determined how and when the A␤(1-42) peptide becomes toxic, whether A␤ aggregates prior to internalization or during the internalization process and, if so, in which intracellular compartments the aggregates form. Elucidating the connection between aggregation and i...

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“…The proportion of aggregation prone residues (APRprop(%)) in a protein sequence was computed using Eq. (2).…”

Section: Prediction Of Aggregation Prone Regions (Aprs)mentioning

confidence: 99%

“…Native conformations of proteins are maintained by a balance between entropy and enthalpy under physiological conditions by avoiding potential intermediates and metastable states, which are prone to misfolding and aggregation. Proteostasis is therefore controlled in each cell by strict regulation of biogenesis, folding (chaperone assisted or otherwise), trafficking and degradation . Even slight disturbances in this regulation can lead to accumulation of misfolded protein aggregates and consequently result in diseases.…”

Section: Introductionmentioning

confidence: 99%

Aggregation prone regions in human proteome: Insights from large‐scale data analyses

et al. 2017

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Protein aggregation leads to several burdensome human maladies, but a molecular level understanding of how human proteome has tackled the threat of aggregation is currently lacking. In this work, we survey the human proteome for incidence of aggregation prone regions (APRs), by using sequences of experimentally validated amyloid-fibril forming peptides and via computational predictions. While approximately 30 human proteins are currently known to be amyloidogenic, we found that 260 proteins (∼1% of human proteome) contain at least one experimentally validated amyloid-fibril forming segment. Computer predictions suggest that more than 80% of the human proteins contain at least one potential APR and approximately two-thirds (65%) contain two or more APRs; spanning 3-5% of their sequences. Sequence randomizations show that this apparently high incidence of APRs has been actually significantly reduced by unique amino acid composition and sequence patterning of human proteins. The human proteome has utilized a wide repertoire of sequence-structural optimization strategies, most of them already known, to minimize deleterious consequences due to the presence of APRs while simultaneously taking advantage of their order promoting properties. This survey also found that APRs tend to be located near the active and ligand binding sites in human proteins, but not near the post translational modification sites. The APRs in human proteins are also preferentially found at heterotypic interfaces rather than homotypic ones. Interestingly, this survey reveals that APRs play multiple, often opposing, roles in the human protein sequence-structure-function relationships. Insights gained from this work have several interesting implications towards novel drug discovery and development. Proteins 2017; 85:1099-1118. © 2017 Wiley Periodicals, Inc.

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Sequence-dependent Internalization of Aggregating Peptides

Cited by 22 publications

References 71 publications

Amyloidogenicity and toxicity of the reverse and scrambled variants of amyloid‐β 1‐42

Amyloidogenicity and toxicity of the reverse and scrambled variants of amyloid‐β 1‐42

Amyloid-β(1–42) Aggregation Initiates Its Cellular Uptake and Cytotoxicity

Aggregation prone regions in human proteome: Insights from large‐scale data analyses

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