DNA for MethylC-seq was prepared from GFP-positive FACS-sorted cells using the DNeasy Blood and Tissue kit (69504, QIAGEN). DNA methylome libraries were prepared using a modified snmC-seq protocol adapted for bulk DNA samples (Luo et al., 2017). 20 ng of purified genomic DNA with 0.5% unmethylated lambda DNA spike-in (D1521, Promega) was bisulfite converted using the EZ DNA Methylation-Direct™ Kit (D5021, Zymo) following the product manual and was eluted in 10 µl M-Elution buffer. 9 µl converted DNA was mixed with 1 µl P5L_random oligo (5 µM, /5SpC3/TTCCCTACACGACGCTCTTCCGATCTNNNNNNNNN, IDT) followed by heat denaturing at 95°C for 3 min using a thermocycler. The samples were chilled on ice for 2 min and mixed with 10 µl enzyme mix containing 2 µl of Blue Buffer (B0110, Enzymatics), 1 µl of 10 mM dNTP (N0447L, NEB), 1 µl of Klenow exo- (50 U/µl, P7010-HC-L, Enzymatics) and 6 µl H2O. The samples were incubated using a thermocycler with the following program: 4°C for 5 min, ramp up to 25°C at 0.1°C/sec, 25°C for 5 min, ramp up to 37°C at 0.1°C/sec, 37°C for 60 min, 4°C. A 3 µl enzyme mix containing 2 µl of Exonuclease 1 (20U/µl, X8010L, Enzymatics) and 1 µl of Shrimp Alkaline Phosphatase (rSAP, M0371L, NEB) was added to the samples. The samples were incubated at 37°C for 30 min using a thermocycler. Samples were cleaned-up using 0.8x SPRI beads and eluted with 10 µl M-Elution buffer. Eluted samples were heated at 95°C for 3 min using a thermocycler and were chilled on ice for 2 min. Samples were mixed with 10.5 ul Adaptase master mix containing 2 ul Buffer G1, 2 ul Regent G2, 1.25 ul Reagent G3, 0.5 ul Enzyme G4, 0.5 ul Enzyme G5 and 4.25 ul M-Elution buffer (Accel-NGS Adaptase Module for Single Cell Methyl-Seq Library Preparation, 33096, Swift Biosciences). Samples were incubated at 37°C for 30 min, 95°C for 2 min and 4°C using a thermocycler. 1 µl 30 µM P5 indexing primer and 5 µl 10 µM P7 indexing primer and 25 µl KAPA HiFi HotStart ReadyMix, (KK2602, KAPA BIOSYSTEMS) were added into each sample followed by thermocycling using the following program - 95°C for 2 min, 98°C for 30 sec, 10 cycles of (98°C for 15 sec, 64°C for 30 sec, 72°C for 2min), 72°C for 5 min and then 4°C. PCR products were cleaned up using 0.8x SPRI beads twice. Methylome libraries were sequenced using an Illumina HiSeq 4000 instrument with 5% PhiX DNA spike-in.
GEO Accession
GSM3040881