Selective Photo-Crosslinking Detection of Methylated Cytosine in DNA Duplex Aided by a Cationic Comb-Type Copolymer

In the process of cell development and differentiation, C-5-methylation of cytosine (5-methylcytosine: 5-mC) in genome DNA is an important transcriptional regulator that switches between differentiated and undifferentiated states. Further, abnormal DNA methylations are often present in tumor suppressor genes and are associated with many diseases. Therefore, 5-mC detection technology is an important tool in the most exciting fields of molecular biology and diagnosing diseases such as cancers. In this study, we found a novel photo-crosslinking property of psoralen-conjugated oligonucleotide (Ps-Oligo) to the double-stranded DNA (ds-DNA) containing 5-mC in the presence of a cationic comb-type copolymer, poly(allylamine)-graft-dextran (PAA-g-Dex). Photo-crosslinking efficiency of Ps-Oligo to 5-mC in ds-DNA was markedly enhanced in the presence of PAA-g-Dex, permitting 5-mC-targeted crosslinking. We believe that the combination of PAA-g-Dex and Ps-Oligo will be an effective tool for detecting 5-mC in genomic DNA.