ciRS-7 exonic sequence is embedded in a long non-coding RNA locus

PLoS Genet. 2017 Dec 13;13(12):e1007114. doi: 10.1371/journal.pgen.1007114. eCollection 2017 Dec.

Abstract

ciRS-7 is an intensely studied, highly expressed and conserved circRNA. Essentially nothing is known about its biogenesis, including the location of its promoter. A prevailing assumption has been that ciRS-7 is an exceptional circRNA because it is transcribed from a locus lacking any mature linear RNA transcripts of the same sense. To study the biogenesis of ciRS-7, we developed an algorithm to define its promoter and predicted that the human ciRS-7 promoter coincides with that of the long non-coding RNA, LINC00632. We validated this prediction using multiple orthogonal experimental assays. We also used computational approaches and experimental validation to establish that ciRS-7 exonic sequence is embedded in linear transcripts that are flanked by cryptic exons in both human and mouse. Together, this experimental and computational evidence generates a new model for regulation of this locus: (a) ciRS-7 is like other circRNAs, as it is spliced into linear transcripts; (b) expression of ciRS-7 is primarily determined by the chromatin state of LINC00632 promoters; (c) transcription and splicing factors sufficient for ciRS-7 biogenesis are expressed in cells that lack detectable ciRS-7 expression. These findings have significant implications for the study of the regulation and function of ciRS-7, and the analytic framework we developed to jointly analyze RNA-seq and ChIP-seq data reveal the potential for genome-wide discovery of important biological regulation missed in current reference annotations.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Algorithms
  • Alternative Splicing
  • Animals
  • Brain Chemistry
  • Exons
  • Female
  • HEK293 Cells
  • Humans
  • Mice
  • Pregnancy
  • RNA / biosynthesis*
  • RNA / genetics*
  • RNA Splicing
  • RNA, Circular
  • RNA, Long Noncoding / genetics
  • Sequence Analysis, RNA / methods

Substances

  • RNA, Circular
  • RNA, Long Noncoding
  • RNA