Mapping and editing of nucleic acid modifications.

Modification on nucleic acid plays a pivotal role in controlling gene expression. Various kinds of modifications greatly increase the information-encoding capacity of DNA and RNA by introducing extra chemical group to existing bases instead of altering the genetic sequences. As a marker on DNA or RNA, nucleic acid modification can be recognized by specific proteins, leading to versatile regulation of gene expression. However, modified and regular bases are often indistinguishable by most conventional molecular methods, impeding detailed functional studies that require the information of genomic location. Recently, new technologies are emerging to resolve the positions of varied modifications on both DNA and RNA. Intriguingly, by integrating regional targeting tools and effector proteins, researchers begin to actively control the modification status of desired gene in vivo. In this review, we summarize the characteristics of DNA and RNA modifications, the available mapping and editing tools, and the potential application as well as deficiency of these technologies in basic and translational researches.