Fig. 3: α-Synuclein down-regulates GBM cells proliferation via the regulation of cyclin D1.

A Stable lentiviral overexpression of α-syn (A, upper) in U87 cells and influence on proliferation assessed by impedance-based approach (N = 12, impaired t test). Actin expression is provided as a control of protein load. Histogram illustrates the slopes of the proliferation curves expressed as percent of Fuw (EV) control cells slope and correspond to the means ± SEM of 4 independent experiments performed in triplicates. ****, P < 0.0001. B Impact of a-syn in U87 cell cycle dynamics by FACS analysis as described in methods. Data are expressed as percent of EV control cells taken and are the means ± SEM of 2 independent experiments performed in triplicates. ****, P < 0.0001 and ns, non-statistically significant. C–F Caspase 3 activity, cyclin D1 (CCND1) protein expression (C), promoter activation (D) and mRNA levels (E) (measured as described in “Methods”) in EV- and α-syn-infected U87 cells (N = 15 impaired t test). Data are expressed as percent of EV control cells (taken as 100%) and are the means ± SEM of 5 independent experiments performed in triplicates. **, P < 0.01; ****, P < 0.0001. Impact of EV or α-syn on the proliferation of 3T3 cells either depleted of cyclin D1 (D1-/CT EV and D1-/CT α-syn) (G, N = 9, unpaired t test) or rescued for cyclin D1 (D1-/CP EV and D1-/CP α-syn) (H, N = 4, Mann–Whitney test). Quantification analyses of the slopes of the curves in G and H correspond to the means ± SEM of 2–3 independent experiments performed in triplicates (G) or duplicates (H). *, P < 0.05; ns, non-statistically significant.