Specific disruption of DNMT1/protein-x interactions. (A) Representation of DNMT1 with its functional domain (nuclear localization signal: NLS, BAH1 and two domains, domain CXXC and its catalytic domain) and with amino acid domains of interaction with DMAP1, HDAC1, Sp1, HP1β, EZH2, DNMT3b and PCNA according to the UniProt website and the literature. Amino acid sequences of peptides cloned in plasmid and able to disrupt specific DNMT1/protein-x interactions are indicated in the “peptide” column; “untreated” indicates that cells were not treated with a peptide encoding by a plasmid, i.e., that cells were only treated with a plasmid encoding for the NLS of interest. (B) Only the expression of the 197–212 peptide promotes a significant decrease of the DNMT1/DNMT3b interaction in Astro#40 cells. Pictures (blue: DAPI staining; red: DNMT1/DNMT3b interaction or close proximity) illustrate the specific disruption of the DNMT1/DNMT3b interaction or close proximity induced by the expression of the 197–212 peptide, while the expression of the 47–60 peptide did not affect the DNMT1/DNMT3b interaction or close proximity. Pictures are representatives of data obtained from 100 cells in three independent experiments. The graph illustrates the average ± SD of these data. (C) Measure of the 5-methylcytosine (5 mC) level in cells (Astro#40 or U87) transfected by plasmid encoding for the indicated peptides or pre-treated with procainamide (0.5 mmol/l each 5 days for 4 weeks) or 5aza-2deoxycytidine (1μM each 5 days for 4 weeks).