Young LINE-1 transposon 5' UTRs marked by elongation factor ELL3 function as enhancers to regulate naïve pluripotency in embryonic stem cells

Nat Cell Biol. 2023 Sep;25(9):1319-1331. doi: 10.1038/s41556-023-01211-y. Epub 2023 Aug 17.

Abstract

LINE-1s are the major clade of retrotransposons with autonomous retrotransposition activity. Despite the potential genotoxicity, LINE-1s are highly activated in early embryos. Here we show that a subset of young LINE-1s, L1Md_Ts, are marked by the RNA polymerase II elongation factor ELL3, and function as enhancers in mouse embryonic stem cells. ELL3 depletion dislodges the DNA hydroxymethylase TET1 and the co-repressor SIN3A from L1Md_Ts, but increases the enrichment of the Bromodomain protein BRD4, leading to loss of 5hmC, gain of H3K27ac, and upregulation of the L1Md_T nearby genes. Specifically, ELL3 occupies and represses the L1Md_T-based enhancer located within Akt3, which encodes a key regulator of AKT pathway. ELL3 is required for proper ERK activation and efficient shutdown of naïve pluripotency through inhibiting Akt3 during naïve-primed transition. Our study reveals that the enhancer function of a subset of young LINE-1s controlled by ELL3 in transcription regulation and mouse early embryo development.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 5' Untranslated Regions
  • Animals
  • Embryonic Stem Cells
  • Mice
  • Nuclear Proteins* / genetics
  • Peptide Elongation Factors
  • Transcription Factors* / genetics

Substances

  • 5' Untranslated Regions
  • Nuclear Proteins
  • Transcription Factors
  • Peptide Elongation Factors