Study of the effect of aromatic interactions on alpha-synuclein aggregation and toxicity.

DELGADO OCAÑA S; GENTILI I; CHESTA ME; VALIENTE-GABIOUD A; ANDRÉS TOMÉ; MAURICIO MENACHO MÁRQUEZ; CLAUDIO O. FERNÁNDEZ

Carlos Paz

Congreso; Alexander von Humboldt Kolleg Current Advances on Neurodegeneration: from Molecular Biology to Translational Medicine.; 2017

Alexander von Humboldt Kolleg

Aggregation of alpha-synuclein (αS) in Parkinson?s disease (PD) results in neuronal death and disease onset. Several mutations in αS gene are associated with familial PD, suggesting again a central role for this protein in the disease. However, the mechanistic details are still elusive.Previous work in our lab demonstrated that the porphyrin phtalocyanine tetrasulfonate (PcTs) directly binds to monomeric, soluble αS. This interaction is driven by aromatic stacking with F4, Y39 and F94 aminoacids, and is crucial to prevent αS aggregation. In order to clarify the importance of Y39 residue on αS aggregation and toxicity, we generated different αS mutations in order to determine the relevance of the aromaticity/hydrofobicity at that position. Through the combination of in vitro and in vivo approches, we determined that mutations in position 39 from tyrosine to alanine or leucine prevented in vitro aggregation of αS and indeed the final products of aggregation showed reduced toxicity on SH-SY5Y human neuroblastoma cells. Interestingly, the expression of these mutants on H4 human neuroglioma cells caused a reduced accumulation of intracellular inclusions when compared to their WT control, although they were able to form oligomeric species when analysed by complementation studies on HEK cells. No differences on in vitro aggregation propensity or in vivo inclusion formation were observed by mutating tyrosine to phenylalanine.Altogether, our data highlight the importance of aromatic interactions in αS aggregation both in vitro and in a cellular context, and establish a common basis to study genetic or pharmacological inhibitors of αS aggregation, offering new perspectives for therapeutic intervention in PD and other synucleinopathies.