Taiwo O, Wilsona GA, Morris T, Seisenberger S, Reik W, Pearce D, Beck S, Butcher LM
To understand the functional consequences of DNA methylation on phenotypic plasticity, a genome - wide analysis should be embraced. This in turn requires a technique that balances accuracy, genome coverage, resolution and cost, yet is low in DNA input to minimise the drain on precious samples. MeDIP-seq fulfils these criteria, combining methylated DNA immunoprecipitation (MeDIP) with massively-parallel DNA sequencing. Methylated DNA Immunoprecipitation (MeDIP) is a technology capable of targeting the vast majority of the methylome. It involves antibodies directed against mC/mCG to precipitate methylated DNA fragments. MeDIP is able to detect methylated cytosines in both mC and mCG contexts. Because antibodies used for MeDIP were raised in a way to yield equal specificity against mC and mCG, MeDIP offers a near -unbiased and hypothesis -free approach without a priori assumptions about which regions of the methylome might be targeted (see below). Combining MeDIP with next generation sequencing (MeDIP-seq; Down et al., 2008), provides highquality methylomes at typically 100-300bp resolution (depending on chosen insert size) at costs comparable to other capture-based techniques (Beck, 2010). In this EpiGeneSys Protocol Collection, which is based in an original publication in Nature Protocols (Taiwo et al., 2012), we detail Nano-MeDIP-seq–a protocol that uses 100-fold less genomic DNA than that which is commonly used for immunoprecipitation -based applications. Applications of this method will result in specific and sensitive enrichment of methylated DNA fragments over a wide range of DNA concentrations (5,000 -50 ng), making Nano-MeDIP-seq suitable for studies nvolving minute clinical samples, micro-dissected tissues and rare cell types.