Nascent-seq indicates widespread cotranscriptional RNA editing in Drosophila

Mol Cell. 2012 Jul 13;47(1):27-37. doi: 10.1016/j.molcel.2012.05.002. Epub 2012 May 31.


The RNA editing enzyme ADAR chemically modifies adenosine (A) to inosine (I), which is interpreted by the ribosome as a guanosine. Here we assess cotranscriptional A-to-I editing in Drosophila by isolating nascent RNA from adult fly heads and subjecting samples to high throughput sequencing. There are a large number of edited sites within nascent exons. Nascent RNA from an ADAR-null strain was also sequenced, indicating that almost all A-to-I events require ADAR. Moreover, mRNA editing levels correlate with editing levels within the cognate nascent RNA sequence, indicating that the extent of editing is set cotranscriptionally. Surprisingly, the nascent data also identify an excess of intronic over exonic editing sites. These intronic sites occur preferentially within introns that are poorly spliced cotranscriptionally, suggesting a link between editing and splicing. We conclude that ADAR-mediated editing is more widespread than previously indicated and largely occurs cotranscriptionally.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adenosine Deaminase / genetics*
  • Animals
  • Binding Sites / genetics
  • Drosophila / classification
  • Drosophila / genetics
  • Drosophila Proteins / genetics*
  • Drosophila melanogaster / genetics*
  • Evolution, Molecular
  • Exons / genetics
  • Gene Expression
  • Introns / genetics
  • Mutation
  • RNA Editing*
  • RNA Precursors / genetics
  • RNA, Messenger / genetics
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transcription, Genetic*


  • Drosophila Proteins
  • RNA Precursors
  • RNA, Messenger
  • Adar protein, Drosophila
  • Adenosine Deaminase

Associated data

  • GEO/GSE37232