Article

Nonspecific Interaction of Prefibrillar Amyloid Aggregates with Glutamatergic Receptors Results in Ca2+ Increase in Primary Neuronal Cells

Department of Physics, University of Genoa, Via Dodecaneso, 33, I-16146 Genoa, Italy.
Journal of Biological Chemistry (Impact Factor: 4.57). 09/2008; 283(44):29950-60. DOI: 10.1074/jbc.M803992200
Source: PubMed

ABSTRACT

It is widely reported that the Ca(2+) increase following nonspecific cell membrane permeabilization is among the earliest biochemical modifications in cells exposed to toxic amyloid aggregates. However, more recently receptors with Ca(2+) channel activity such as alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA), N-methyl D-aspartate (NMDA), ryanodine, and inositol 1,4,5-trisphosphate receptors have been proposed as mediators of the Ca(2+) increase in neuronal cells challenged with beta-amyloid peptides. We previously showed that prefibrillar aggregates of proteins not associated with amyloid diseases are toxic to exposed cells similarly to comparable aggregates of disease-associated proteins. In particular, prefibrillar aggregates of the prokaryotic HypF-N were shown to be toxic to different cultured cell lines by eliciting Ca(2+) and reactive oxygen species increases. This study was aimed at assessing whether NMDA and AMPA receptor activations could be considered a generic feature of cell interaction with amyloid aggregates rather than a specific effect of some aggregated protein. Therefore, we investigated whether NMDA and AMPA receptors were involved in the Ca(2+) increase following exposure of rat cerebellar granule cells to HypF-N prefibrillar aggregates. We found that the intracellular Ca(2+) increase was associated with the early activation of NMDA and AMPA receptors, although some nonspecific membrane permeabilization was also observed at longer times of exposure. This result matched a significant co-localization of the aggregates with both receptors on the plasma membrane. Our data support the possibility that glutamatergic channels are generic sites of interaction with the cell membrane of prefibrillar aggregates of different peptides and proteins as well as the key structures responsible for the resulting early membrane permeabilization to Ca(2+).

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    • "First, it forms fibrils that are morphologically, tinctorially and structurally similar to those found in amyloid deposition diseases (Chiti et al., 2001;Relini et al., 2004). Second, HypF-N forms pre-fibrillar oligomers that are toxic to cells in culture and in animal models (Bucciantini et al., 2002Bucciantini et al., , 2004Cecchi et al., 2005;Baglioni et al., 2006;Pellistri et al., 2008). Furthermore, HypF-N pre-fibrillar oligomers have similar pathogenic effects as Aβ oligomers on cells at the biochemical, molecular, electrophysiological and animal level (Bucciantini et al., 2004;Tatini et al., 2013). "
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