Scientific Results

Molecular insights into cell toxicity of a novel familial amyloidogenic variant of ß2-microglobulin

Year: 2016

Authors: Leri M., Bemporad F., Oropesa-Nuñez R., Canale C., Calamai M., Nosi D., Ramazzotti M., Giorgetti S., Pavone F. S., Bellotti V., Stefani M., Bucciantini M.

Autors Affiliation: Dipartimento di Scienze Biomediche Sperimentali e Clinche “Mario Serio”- Università degli Studi di Firenze, 50134 Firenze, Italy; Dipartimento di Nanofisica, Istituto Italiano di Tecnologia, 16163 Genova, Italy; European Laboratory for Non-linear Spectroscopy (LENS) – Università degli Studi di Firenze, 50019 Sesto Fiorentino, Italy; National Institute of Optics, Consiglio Nazionale delle Ricerche (CNR), 50125 Firenze, Italy; Dipartimento di Medicina Sperimentale e Clinica – Università degli Studi di Firenze, 50134 Firenze, Italy; Dipartimento di Medicina Molecolare – Istituto di Biochimica – Università degli Studi di Pavia, 27100 Pavia, Italy; Wolfson Drug Discovery Unit, Centre for Amyloidosis and Acute Phase Proteins, Division of Medicine, Royal Free Campus University College London, NW3 2PF London, UK; Centro Interuniversitario per lo Studio delle Malattie Neurodegenerative (CIMN), 50134 Firenze, Italy

Abstract: The first genetic variant of beta 2-microglobulin (b2M) associated with a familial form of systemic amyloidosis has been recently described. The mutated protein, carrying a substitution of Asp at position 76 with an Asn (D76N b2M), exhibits a strongly enhanced amyloidogenic tendency to aggregate with respect to the wild-type protein. In this study, we characterized the D76N b2M aggregation path and performed an unprecedented analysis of the biochemical mechanisms underlying aggregate cytotoxicity. We showed that, contrarily to what expected from other amyloid studies, early aggregates of the mutant are not the most toxic species, despite their higher surface hydrophobicity. By modulating ganglioside GM1 content in cell membrane or synthetic lipid bilayers, we confirmed the pivotal role of this lipid as aggregate recruiter favouring their cytotoxicity. We finally observed that the aggregates bind to the cell membrane inducing an alteration of its elasticity (with possible functional unbalance and cytotoxicity) in GM1-enriched domains only, thus establishing a link between aggregate-membrane contact and cell damage.


Volume: 20 (8)      Pages from: 1443  to: 1456

More Information: This project was supported by the Italian Ministry for Education University and Research (MIUR) framework \”Futuro in Ricerca 2010\” and by Fondazione Cassa di Risparmio di Pistoia e Pescia (Project no. 2014.0251). M.R. were supported by MIUR framework \’Futuro in Ricerca 2010\’ (no. RBFR109EOS). M.L. was supported by grant from Ente Cassa di Risparmio di Firenze (no. 2013.0697); M.C. was supported by Italian MIUR in the framework of the Flagship Project NANOMAX, European Community\’s Seventh Framework Programme (FP7 2007-2013, LASERLABEUROPE). F.B. research is currently funded by the \’Programma per giovani ricercatori Rita Levi Montalcini 2010\’ from the Italian MIUR.
KeyWords: amyloid protein; beta 2 microglobulin; congo red; ganglioside GM1; quantum dot; reactive oxygen metabolite; thioflavine, amyloidosis; Article; cell death; cell viability; circular dichroism; cytotoxicity; diffusion coefficient; elasticity; human; human cell; immunofluorescence; light scattering; lipid vesicle; priority journal; protein folding; quantitative analysis; T cell depletion; transmission electron microscopy
DOI: 10.1111/jcmm.12833

Citations: 14
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