Fibrillar aggregates of an amyloidogenic variant of apolipoprotein A-I. Structure and cellular reactivity

GISONNO RA; PRIETO ED; CURTO LM; GORGOJO JP; RODRIGUEZ ME; SCHINELLA GR; TRICERRI MA; RAMELLA NA

La Plata

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Biofísica; 2018

Sociedad Argentina de Biofisica

Different protein conformations may be involved in the development of the clinical manifestations associated to human amyloidosis1. Even though a fibrillar conformation is usually the signature of damage in the tissues of patients, it is not clear whether this specie is per se the cause or the consequence of the disease.Human apolipoprotein A-I (apoA-I)-derived amyloidosis is poorly known. About 20naturally occurring mutations have been described in patients suffering multipleorgan failure. The reason of apoA-I variants misfolding and aggregation is far to be known. We have previously incubated different natural variants under mild acidic conditions and in the presence of ligands as heparin, and shown that under short periods and low protein concentrations mainly oligomeric species are obtained2.Here we set up to characterize the folding of a natural variant (apoA-ILys107-0)which induces amyloidosis plus severe atherosclerosis. With the hypothesis that a pro-inflammatory micro environment could favor protein misfolding, we oxidizedthis variant under controlled amounts of H2O2 and incubated by 30 days at pH6.0. LC-MS/MS mass spec analysis indicated oxidation of Met 148 and Circulardichroism analysis showed a loss in the alpha helical structure. Transmissionelectron and atomic force microscopy confirmed the presence of fibrils whichstrongly bind the amyloid-indicative probe Thioflavin T. Interestingly, thisconformation was reactive to induce the formation of neutrophil extracellular traps (NETs) from healthy donor. Our results suggest that the fibrillar conformation of this variant may elicit a pro inflammatory cellular response which participate in the severity of the clinical chronic landscape.