ChIP Assay with Chromatin Immunoprecipitation

The ChIP assays were conducted using the EZ-Magna ChIP™ G - Chromatin Immunoprecipitation Kit (EMD Millipore) ^{25 (link)}. Briefly, the homogenate from the DRG was cross-linked with 1% formaldehyde and terminated by glycine. After centrifugation, the collected pellet was resuspended with nuclear lysis buffer and sonicated to shear the cross-linked DNA. After centrifugation, the supernatant was diluted and respectively subjected to immunoprecipitation overnight at 4°C with protein G magnetic beads plus 3 μg of rabbit anti-DNMT3a (Abcam) or 3 μg of normal rabbit serum. Input was used as a positive control. After incubation, protein G magnetic beads were pelleted with the magnetic separator and washed respectively with low salt buffer, high salt buffer, LiCl buffer and TE buffer. The protein/DNA complexes were eluted and reversed to free DNA. The DNA fragments were purified and identified using PCR/real-time PCR with the primers (Supplementary Table 1).