ADAR1 RNA-Editing Enzyme Regulates Telomeric R-Loop Formation

The enzyme adenosine deaminase acting on RNA (ADAR) plays a key role in editing RNA by converting adenosine to inosine, a process known as A-to-I RNA editing. Initially, ADAR was identified as an enzyme responsible for converting adenosine to inosines, specifically in dsRNA. However, recent studies indicate that ADAR1 can also edit DNA on hybrid strands composed of DNA:RNA strands. One of the representative structures in cells is the R-loop, which is formed at open DNA regions with single-stranded DNA and DNA:RNA hybrid strands, through hybridization of the cis-transcript or an invading RNA strand with the template DNA. In the previous study, authors have shown that ADAR1 regulates the R-loop formation and genome stability at telomeres in cancer cells carrying noncanonical variants of telomeric repeats.In this chapter, the latest and basic protocols to measure the accumulation and formation of the R-loop are described.