Dear Editor, R-loops are three-stranded nucleic acid structures consisting of a DNA:RNA heteroduplex and a displaced single DNA strand.They constitute a prevalent genomic feature with important functions in all kingdoms of eukaryotes.1-3 For example,R-loops have been found over unmethylated CpG island promoters,G-rich terminators,and many other regulatory chromosomal loci.2,3 Moreover,they are essential for diverse cellular processes,such as immunoglobulin class switching,mitotic chromosome segregation,4 DNA replication and repair,genome stability regulation,5 as well as in multiple steps during transcription.6,7 R-loops can be formed both in cis and in trans;cis R-loops are formed between a nascent RNA and its DNA template following transcribing RNA polymerases and exert co-transcriptional regulatory effects.3,8 Therefore,it is important to control their formation and resolution,and many external factors have already been identified for this process.7 However,it is still unknown whether the intrinsic properties of the RNA itself,such as various modifications,can modulate the formation of DNA:RNA hybrids.
展开▼
