128 - Lipid-Derived Electrophiles Induce Covalent Modification and Aggregation of Cu,Zn-Superoxide Dismutase in a Hydrophobicity-Dependent Manner

Abstract

Unsaturated lipids are highly susceptible to oxidation induced by reactive oxygen species and enzymes, leading to the formation of lipid hydroperoxides, ketones, alcohols and aldehydes. Reactive aldehydes can modify macromolecules such as proteins, resulting in loss of function and/or aggregation. Accumulation of copper, zinc-superoxide dismutase (Cu,Zn-SOD, SOD1) immunoreactive aggregates is associated with some cases of amyotrophic lateral sclerosis (ALS). The mechanism by which SOD1 forms those aggregates in motor neurons is still not clear, however recent studies have shown that it may be linked to lipids and membranes. This study aimed to evaluate the potential of different lipid-derived electrophiles to induce formation of SOD1 aggregates in vitro. Alkynyl 4-hydroxy-2-nonenal (logPcal=0.57), trans-2-hexen-1-al (logPcal=1.67), trans,trans-2,4-nonadienal (logPcal=3.01), trans,trans-2,4-decadienal (logPcal=3.50) and cholesterol secosterol aldehydes (logPcal=6.45/6.48) were incubated with SOD1 at 37°C for 24h. Size exclusion chromatography and SDS-PAGE confirmed that these aldehydes induce SOD1 aggregation. More importantly, we were able to demonstrate that SOD1 aggregation increases proportionally to the hydrophobicity of the aldehydes (r2=0.9202). Further analysis by MALDI-TOF of intact SOD1 derived from our in vitro incubations revealed that SOD1 was covalently modified by aldehydes. Our data thus suggest that lipid-derived electrophiles may play significant roles in protein aggregation in neurodegenerative diseases, leading to believe that it could be a hydrophobicity-dependent process. Acknowledgment CNPq, FAPESP, INCT/NAP/CEPID-Redoxoma, Pró-Reitoria de Pesquisa-USP.