Structural characterization of membrane-induced GAPDH prefibrillar species and its implications in Parkinson disease

TORRES-BUGEAU, CLARISA; AVILA, CESAR L.; GONZÁLEZ-LIZÁRRAGA, FLORENCIA; VERA, CECILIA

Congreso; XXIX Reunião Anual da Federação de Sociedades de Biologia Experimental (FeSBE); 2014

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a multifunctional enzyme that has been associated to neurodegenerative diseases. GAPDH colocalizes with α -synuclein in amyloid aggregates in post-mortem tissue of patients with sporadic Parkinson disease and promotes the formation of Lewy body-like inclusions in cell culture. In a previous work, we showed that in vitro heparin can trigger GAPDH amyloid aggregation and that prefibrillar species present during the aggregation process can modify the α-synuclein aggregation kinetic. The heparin-induced GAPDH prefibrillar species are capable to abolish the toxicity of α-synuclein species in cell cultures. The GAPDH prefibrillar species responsible for this activity were structurally characterized as protofibrils. We have also demonstrated that acidic membranes can trigger the GAPDH amyloid aggregation. However, structural and functional features of membrane-induced GAPDH prefibrillar species were not studied, and thus, its effectiveness on α-synuclein aggregation kinetic is unknown.Objectives: The aim of the present work is to perform a structural and functional characterization of membrane-induced GAPDH prefibrillar species, and to compare them to heparin-induced GAPDH prefibrillar species.Methods: The work does not involve animal or human experiments. Structural characterization of GAPDH prefibrillar species was performed using Fourier transform (FT-IR) together with Small Angle X-Ray Scattering (SAXS). Biocomputational techniques were used to obtain a model of GAPDH-membrane interaction.Results: In this work we demonstrated that membrane-induced and heparin-induced GAPDH prefibrillar species are structurally different. This suggest that aggregation evolves through different pathways. Aggregation was seen to be dependent on membrane composition, curvature and fluidity. Using biocomputational techniques we modeled GAPDH:membrane interaction. We observed that both hydrophobic and electrostatic forces drive the aggregation process induced by membranes . On the contrary, heparin induced aggregation was driven mainly by electrostatic forces. These differences arising during the first steps of aggregation, could explain the differences in the aggregation pathway.