Genome-Wide Analysis of DNA Methylation in Single Cells Using a Post-bisulfite Adapter Tagging Approach

DNA methylation is an epigenetic mark implicated in the regulation of key biological processes. Using high-throughput sequencing technologies and bisulfite-based approaches, it is possible to obtain comprehensive genome-wide maps of the mammalian DNA methylation landscape with a single-nucleotide resolution and absolute quantification. However, these methods were only applicable to bulk populations of cells. Here, we present a protocol to perform whole-genome bisulfite sequencing on single cells (scBS-Seq) using a post-bisulfite adapter tagging approach. In this method, bisulfite treatment is performed prior to library generation in order to both convert unmethylated cytosines and fragment DNA to an appropriate size. Then DNA fragments are pre-amplified with concomitant integration of the sequencing adapters, and libraries are subsequently amplified and indexed by PCR. Using scBS-Seq we can accurately measure DNA methylation at up to 50% of individual CpG sites and 70% of CpG islands.