Nuclei were isolated by transferring 400 ul of supernatant in a plastic tube and sequentially added 400 ul of 50% Iodixanol solution (homogenization buffer and 50% Iodixanol solution), 600 ul of 29% Iodixanol (homogenization buffer, 160 mM and 29% Iodixanol solution) and 600 ul of 35% Iodixanol solution (homogenization buffer, 160 mM and 35% Iodixanol solution) to the bottom of the tube, avoiding mixture of layers. We centrifuged for 20 min at 3,000 RCF and we discarded upper layers of the gradient in order to collect 200 ul from the nuclei band. We counted nuclei and transferred 50.000 into a tube with 1 ml of ATAC-Resuspension Buffer (RSB) + 0.1% Tween-20 (10 mM Tris-HCl pH 7.4, 10 mM NaCl, 3 mM MgCl2, 0.1% Tween-20). We pelleted nuclei by centrifuging for 10 minutes at 500 RCF and resuspended in 50 ul cold ATAC-RSB containing 0.1% NP40, 0.1% Tween-20, and 0.01% Digitonin,. We lysed for 3 minutes on ice and washed with 1 ml of cold ATAC-RSB + 0.1% Tween-20. We transposed the samples by resuspending nuclei in 50 ul of transposition mix (25 ul 2x TD buffer, 100nM transposase, 16.5 ul PBS, 0.5 ul 1% digitonin, 0.5 ul 10% Tween-20, 5 ul H2O) and incubated at 37°C for 30 minutes. We purified the transposed DNA using the Qiagen MinElute PCR Purification Kit (cat. # 28004) and eluted in 10 μl elution buffer. Next we amplified the transposed DNA fragments in the PCR mix (10 μl transposed DNA, 10 μl nuclease-free H2O, 2.5 μl 25 μM PCR Primer 1, 2.5 μl 25 μM Barcoded PCR Primer 2 and 25 μl NEB Next High-Fidelity 2× PCR Master Mix cat. # M0541L). The final ATAC-seq libraries were purified using the Qiagen MinElute PCR Purification Kit, quantified at the Qubit Fluorometer (Invitrogen, cat. #Q33226) and quality controlled with the High Sensitivity DNA Assay at the 2100 Bioanalyzer (Agilent, cat. # G2939BA). Four and three independent biological replicates, sequenced as independent libraries, were performed for Gabra6-cre;LSL-SmoM2 and control Gabra6-cre, respectively. Two independent biological replicates, sequenced as independent libraries, were performed for hSynI-creER+LSL-tdTomato, hSynI-creER+LSL-BRPF1 TR, hSynI-creER+LSL-SmoM2 and hSynI-creER+LSL-SmoM2+LSL-BRPF1 TR cell lines. All libraries were sequenced as single reads of 50 bp with the Illumina HiSeq2500.