Analysis of the sarkosyl-insoluble proteomes of Parkinson’s disease and Multiple System Atrophy subject brain samples

Aggregated alpha-synuclein (α-syn) is a principal constituent of Lewy bodies (LBs) and glial cytoplasmic inclusions (GCIs) that are observed respectively inside neurons in Parkinson’s disease (PD) and oligodendrocytes in multiple system atrophy (MSA). Yet, the cellular origin, the exact pathophysiological role, and the mechanism of formation of these inclusions remain to be elucidated. It has recently been proposed that pathological α-syn inclusions are capable of eventually causing the demise of the host cell by virtue of the cumulative sequestration of partner proteins and organelles. In particular, the hypothesis of a local cross-seeding of other fibrillization-prone proteins like tau or TDP-43 has also been put forward. The objective of this study was to examine the composition of these inclusions to gain insight into their origin and mechanisms of formation. We submitted sarkosyl-insoluble extracts of post-mortem brain tissue from PD and MSA patients and control subjects to a comparative proteomic analysis to address these points.