The isolation of brain nuclei prior to the flow cytometry separation was performed mostly as previously described in Kozlenkov et al. (Sci Adv. 2018). Tissue (~300 mg) was homogenized in ice-cold lysis buffer (320 mM sucrose, 5 mM CaCl2, 3 mM Mg(Ac)2, 0.1 mM EDTA, 0.1% Triton X-100, 1 mM DTT, 1 U/µl Recombinant RNase Inhibitor (RRI; Takara, Cat. # 2313A), and 10mM Tris-HCl, pH 8.0), underlaid with the sucrose buffer (1.8 M Sucrose, 3 mM Mg(Ac)2, 1 mM DTT, 0.4 U/µl RRI, and 10 mM Tris-HCl pH 8.0), and centrifuged for 1h at 24,000 rpm. The nuclear pellets were then resuspended in the antibody-incubation buffer (0.5% BSA, 3mM MgCl2, 1 U/µl RRI, and 10 mM Tris-HCl, pH 8.0) and incubated with antibodies against NeuN and SOX10 for 1 hr at 4°C. Fluorescence-activated nuclei sorting (FANS) was then used to isolate neurons (NeuN+SOX10- population), oligodendrocyte lineage cells (NeuN-SOX10+ population), consisting of mature oligodendrocytes and a smaller population of OPCs, and a third population (NeuN-SOX10-; hereafter “other glia”) that mostly consisted of astrocytes and microglia. Alexa488-conjugated anti-NeuN antibodies (1:1000 dilution, Millipore, Cat. # MAB377x) and anti-SOX10 antibodies (R&D Systems, Cat. # AF2864) that were custom conjugated to Alexa647 (1:150 dilution, Cat# FCMAB317PE, Millipore) were used. DNA stain DAPI was used to label intact nuclei. From each sample, 250-300K nuclei of neurons, 250-300K of oligodendrocytes, and 150-200K nuclei of other glia were collected. Nuclei were collected directly to the lysis buffer from PicoPure RNA Isolation Kit (ThermoFisher Scientific, Cat. # KIT024), which was then used for RNA isolation. RNA-seq libraries were prepared with the SMARTer Stranded Total RNA-seq Kit, Pico-Input v2 (Takara, Cat. # 634414) from 10ng of the RNA. Libraries were sequenced on a NovaSeq 6000 instrument (Illumina), using paired-end 100 cycles protocol to an average of 120 million read pairs per sample.