P42-TAT inhibits efficiently polyQ-hHtt aggregation. HeLa cells were transfected with GFP-138Q-hHtt171aa (detected in green), in the presence of: BS empty vector (A, A’, A”); Cherry-P42 (B, B’, B”); Cherry-P42-TAT (C, C’, C”); or TAMRA-P42-TAT (D, D’, D”). Cherry and TAMRA are detected in red. As Cherry-P42 (B), Cherry-P42-TAT (C) is present both in the cytoplasm and in the nucleus (visualised by DAPI, in blue). The synthetic peptide TAMRA-P42-TAT provided in the culture medium is internalized into the cells and form vesicles (D). The delivery of P42-TAT inhibits aggregation (C’, D’), as does P42 (B’), to compare to A’. (E) Filter retardation assays were performed on transfected cells in presence of increasing amounts of P42-TAT (0.1, 1.5, 1, 5, 10 or 20 μM) delivered into the medium. A representative dot blot, where GFP is monitored, is shown. Quantification was performed by Image J on 3 independent experiments and is reported on a graph, with respect to the control (BS) set up at 100%. As a control, quantification of cells co-transfected by GFP-138Q-hHtt171aa and Cherry-P42-TAT is shown (P42-TAT). Data represent means +/−SEM, and were analysed using Student’s t. test (*** p < 0,001).