Xist RNA repeat E is essential for ASH2L recruitment to the inactive X and regulates histone modifications and escape gene expression

PLoS Genet. 2017 Jul 7;13(7):e1006890. doi: 10.1371/journal.pgen.1006890. eCollection 2017 Jul.

Abstract

Long non-coding RNA Xist plays a crucial role in establishing and maintaining X-chromosome inactivation (XCI) which is a paradigm of long non-coding RNA-mediated gene regulation. Xist has Xist-specific repeat elements A-F which are conserved among eutherian mammals, underscoring their functional importance. Here we report that Xist RNA repeat E, a conserved Xist repeat element in the Xist exon 7, interacts with ASH2L and contributes to maintenance of escape gene expression level on the inactive X-chromosome (Xi) during XCI. The Xist repeat E-deletion mutant female ES cells show the depletion of ASH2L from the Xi upon differentiation. Furthermore, a subset of escape genes exhibits unexpectedly higher expression in the repeat E mutant cells than the cells expressing wildtype Xist during X-inactivation, whereas the silencing of X-linked non-escape genes is not affected. We discuss the implications of these results to understand the role of ASH2L and Xist repeat E for histone modifications and escape gene regulation during random X-chromosome inactivation.

MeSH terms

  • Animals
  • Cell Differentiation / genetics
  • DNA-Binding Proteins / biosynthesis
  • DNA-Binding Proteins / genetics*
  • Embryonic Stem Cells / metabolism
  • Exons / genetics
  • Gene Deletion
  • Gene Expression Regulation
  • Gene Silencing
  • Histone Code / genetics
  • Mice
  • Nuclear Proteins / biosynthesis
  • Nuclear Proteins / genetics*
  • RNA, Long Noncoding / genetics*
  • Transcription Factors / biosynthesis
  • Transcription Factors / genetics*
  • Transcription, Genetic*
  • X Chromosome / genetics
  • X Chromosome Inactivation / genetics*

Substances

  • Ash2l protein, mouse
  • DNA-Binding Proteins
  • Nuclear Proteins
  • RNA, Long Noncoding
  • Transcription Factors
  • XIST non-coding RNA