Broad neutralization of calcium-permeable amyloid pore channels with a chimeric Alzheimer/Parkinson peptide targeting brain gangliosides

Abstract

Growing evidence supports a role for brain gangliosides in the pathogenesis of neurodegenerative diseases including Alzheimer's and Parkinson's. Recently we deciphered the ganglioside-recognition code controlling specific ganglioside binding to Alzheimer's β-amyloid (Aβ1-42) peptide and Parkinson's disease-associated protein α-synuclein. Cracking this code allowed us to engineer a short chimeric Aβ/α-synuclein peptide that recognizes all brain gangliosides. Here we show that ganglioside-deprived neural cells do no longer sustain the formation of zinc-sensitive amyloid pore channels induced by either Aβ1-42 or α-synuclein, as assessed by single-cell Ca(2+) fluorescence microscopy. Thus, amyloid channel formation, now considered a key step in neurodegeneration, is a ganglioside-dependent process. Nanomolar concentrations of chimeric peptide competitively inhibited amyloid pore formation induced by Aβ1-42 or α-synuclein in cultured neural cells. Moreover, this peptide abrogated the intracellular calcium increases induced by Parkinson's-associated mutant forms of α-synuclein (A30P, E46K and A53T). The chimeric peptide also prevented the deleterious effects of Aβ1-42 on synaptic vesicle trafficking and decreased the Aβ1-42-induced impairment of spontaneous activity in rat hippocampal slices. Taken together, these data show that the chimeric peptide has broad anti-amyloid pore activity, suggesting that a common therapeutic strategy based on the prevention of amyloid-ganglioside interactions is a reachable goal for both Alzheimer's and Parkinson's diseases.

A mirror code for protein-cholesterol interactions in the two leaflets of biological membranes

“…At this stage, the potential applications of the mirror code in the clinical realm remain unclear. Since CARC/CRAC motifs are present in many membrane proteins, any cholesterol modulator might cause some unpredictable effects, this perhaps being a disadvantage in drug target design and clinical treatment: nevertheless, disrupting the association of membrane cholesterol with amyloid proteins efficiently prevented amyloid pore formation in cultured brain cells without undesirable side effects 43 44 . Moreover, mutations of basic residues in TM domains are often associated with protein malfunction and subsequent disease in humans 45 .…”

Comparison of the amyloid pore forming properties of rat and human Alzheimer’s beta-amyloid peptide 1-42: Calcium imaging data

“…SH-SY5Y cells were plated (45.000 cells/dish) in 35 mm culture dishes and grown during 72 h at 37 °C. They were loaded with 5 µM Fluo-4AM for 30 min in the dark as previously described [1] , [5] . The calcium fluxes were estimated by measuring the variation of cell fluorescence intensity after the injection of either rat or human Aβ1-42 (220 nM) into the recording chamber directly above an upright microscope objective (BX51W Olympus) equipped with an illuminator system MT20 module.…”

“…Amyloid pores [1] , [2] , [3] , [4] are responsible for a dramatic increase of intracellular Ca 2+ levels in brain cells that can be measured by fluorescence microscopic imaging [5] , [6] , [7] , [8] , [9] , [10] , [11] , [12] . The dataset presented here contains the values of intracellular Ca 2+ concentrations induced by human and rat Aβ1-42 peptides in neural SH-SY5Y cells.…”

“… Ca 2+ fluxes induced by human and rat Aβ1-42 peptides in SH-SY5Y cells: a comparative study. Amino acid sequence alignments (upper panel) show that human and rat Aβ1-42 peptides differ at only three positions, all located in the ganglioside-binding domain (GBD) [1] , [12] . SH-SY5Y cells treated with the calcium dye Fluo-4AM were incubated with human Aβ1-42 (blue histogram, n =87) or rat Aβ1-42 (red histogram, n =120) and calcium-dependent fluorescence was recorded after 60 min of incubation with the indicated peptides (lower panel).…”

“…Since rat Aβ1-42 differs from its human counterpart at only three amino acid positions, this comparative study is a good assessment of the specificity of the amyloid pore forming assay. The interpretation of this dataset is presented in the accompanying study “Broad neutralization of calcium-permeable amyloid pore channels with a chimeric Alzheimer/Parkinson peptide targeting brain gangliosides” [1] .…”