Fig. 1

Validation of the HS3ST1^−/− HCT-116 cell line with HSPGs-mediated uptake of tau PFFs. a, b Treatment of HCT-116 cells with either heparinase (a) or heparin (b) results in a reduction of tau-AF488 seeds uptake, confirming a role for a HSPGs-mediated uptake mechanism (c) The mRNA expression profile of HS3STs in HCT-116 cell line, analyzed by qPCR (TaqMan), shows that only the HS3ST1 isoform is expressed by this cell line. d mRNA expression levels of the HS3ST1 isoform in WT and HS3ST1^−/− cells by qPCR (TaqMan), demonstrate an 80% reduction of HS3ST1 mRNA levels in the HS3ST1^−/− cell line when compared to WT (Mann-Whitney test between WT and HS3ST1^−/− cells, * p < 0.05). e Immunostaining of exogenous ATIII bound to cell surface HS in HS3ST1^−/− cells (top right) and WT (top left, bottom left and right) showing reduced ATIII signal in HS3ST1^−/− cells, as well as WT cells pre-treated with either heparinase or heparin (bottom panel). Frames show the cell membrane staining, demonstrating the overlap between the ATIII signal and the cell membrane. For image acquisition, 13 fields with 4 z-stacks were analysed with around 2000 cells per field. f quantification of ATIII signal intensity normalized to background levels revealing a significant reduction of ATIII signal in HS3ST1^−/− cells, comparable to the control condition (no exogenous ATIII added) (Kruskal-Wallis with Dunn’s post hoc test to compare WT cells ATIII intensity to the other conditions, * p < 0.05). Data represented as mean ± SD of 3 or 4 independent experiments (biological replicates)