Fig. 1

Recombinant aSyn monomers and fibrils are internalized by H4 cells. a Recombinant aSyn monomers (aSyn Mono) or fibrils (aSyn Fibrils) were added to the cell culture medium and incubated for 24 h. b SDS-PAGE and immunoblot analysis of the recombinant monomeric or fibrillar species of aSyn used in the experiments. The monomers show also the presence of a small fraction of dimers, as displayed by the faint band at 35 kDa. In the fibril preparation, one can observe the presence of higher molecular weight (HMW) species that are stable even on an SDS-PAGE. c Western blot (WB) of H4 cells after treatment with aSyn, confirming the internalization of aSyn monomers or fibrils as seen by the increase in the levels of aSyn in cells that were treated with monomers or fibrils (actin is used as a loading control). d Quantification of the immunoblots. Statistical test was performed using one-way ANOVA followed by Tukey’s post-hoc tests, *p < 0.01. e Epifluorescence microscopy of cells treated as indicated. Scale bar: 30 μm. f TIRF microscopy of cells treated with aSyn monomers or fibrils (green) and stained with Phalloidin (red) confirm intracellular localization of aSyn. Scale bar: 30 μm