To investigate the interaction between amyloid assemblies and “lipid-rafts”, we performed functional and structural experiments on salmon calcitonin (sCT) solutions rich in prefibrillar oligomers, proto- and mature-fibers interacting with liposomes made of monosialoganglioside-GM1 (4%), DPPC (48%) and cholesterol (48%). To focus on the role played by electrostatic forces and considering that sCT is positive and GM1 is negative at physiologic pH, we compared results with those relative to GM1-free liposomes while, to assess membrane fluidity eects, with those relative to cholesterol-free liposomes. We investigated functional eects by evaluating Ca2+-influx in liposomes and viability of HT22-DIFF neurons. Only neurotoxic solutions rich in unstructured prefibrillar oligomers were able to induce Ca2+-influx in the “lipid-rafts” model, suggesting that the two phenomena were correlated. Thus, we investigated protein conformation and membrane modifications occurring during the interaction: circular dichroism showed that “lipid-rafts” fostered the formation of -structures and energy filtered-transmission electron microscopy that prefibrillar oligomers formed pores, similar to A did. We speculate that electrostatic forces between the positive prefibrillar oligomers and the negative GM1 drive the initial binding while the hydrophobic profile and flexibility of prefibrillar oligomers, together with the membrane fluidity, are responsible for the subsequent pore formation leading to Ca2+-influx and neurotoxicity.

The Interaction between Amyloid Prefibrillar Oligomers of Salmon Calcitonin and a Lipid-Raft Model: Molecular Mechanisms Leading to Membrane Damage, Ca2+-Influx and Neurotoxicity / Diociaiuti, Marco; Bombelli, Cecilia; Zanetti-Polzi, Laura; Belfiore, Marcello; Fioravanti, Raoul; Macchia, Gianfranco; Giordani, Cristiano. - In: BIOMOLECULES. - ISSN 2218-273X. - 10:1(2019). [10.3390/biom10010058]

The Interaction between Amyloid Prefibrillar Oligomers of Salmon Calcitonin and a Lipid-Raft Model: Molecular Mechanisms Leading to Membrane Damage, Ca2+-Influx and Neurotoxicity

Bombelli, Cecilia;Zanetti-Polzi, Laura;Belfiore, Marcello;Fioravanti, Raoul;
2019

Abstract

To investigate the interaction between amyloid assemblies and “lipid-rafts”, we performed functional and structural experiments on salmon calcitonin (sCT) solutions rich in prefibrillar oligomers, proto- and mature-fibers interacting with liposomes made of monosialoganglioside-GM1 (4%), DPPC (48%) and cholesterol (48%). To focus on the role played by electrostatic forces and considering that sCT is positive and GM1 is negative at physiologic pH, we compared results with those relative to GM1-free liposomes while, to assess membrane fluidity eects, with those relative to cholesterol-free liposomes. We investigated functional eects by evaluating Ca2+-influx in liposomes and viability of HT22-DIFF neurons. Only neurotoxic solutions rich in unstructured prefibrillar oligomers were able to induce Ca2+-influx in the “lipid-rafts” model, suggesting that the two phenomena were correlated. Thus, we investigated protein conformation and membrane modifications occurring during the interaction: circular dichroism showed that “lipid-rafts” fostered the formation of -structures and energy filtered-transmission electron microscopy that prefibrillar oligomers formed pores, similar to A did. We speculate that electrostatic forces between the positive prefibrillar oligomers and the negative GM1 drive the initial binding while the hydrophobic profile and flexibility of prefibrillar oligomers, together with the membrane fluidity, are responsible for the subsequent pore formation leading to Ca2+-influx and neurotoxicity.
2019
amyloid proteins; neurotoxicity; lipid-rafts; GM1; cholesterol; salmon calcitonin; circular dichroism; transmission electron microscopy; ca2+-influx
01 Pubblicazione su rivista::01a Articolo in rivista
The Interaction between Amyloid Prefibrillar Oligomers of Salmon Calcitonin and a Lipid-Raft Model: Molecular Mechanisms Leading to Membrane Damage, Ca2+-Influx and Neurotoxicity / Diociaiuti, Marco; Bombelli, Cecilia; Zanetti-Polzi, Laura; Belfiore, Marcello; Fioravanti, Raoul; Macchia, Gianfranco; Giordani, Cristiano. - In: BIOMOLECULES. - ISSN 2218-273X. - 10:1(2019). [10.3390/biom10010058]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1345440
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