Holocarboxylase synthetase synergizes with methyl CpG binding protein 2 and DNA methyltransferase 1 in the transcriptional repression of long-terminal repeats

Jing Xue, Subhashinee S K Wijeratne, Janos Zempleni

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

Holocarboxylase synthetase (HLCS) is a chromatin protein that facilitates the creation of histone H3 lysine 9-methylation (H3K9me) gene repression marks through physical interactions with the histone methyltransferase EHMT-1. HLCS knockdown causes a depletion of H3K9me marks in mammalian cell cultures and severe phenotypes such as short lifespan and low stress resistance in Drosophila melanogaster. HLCS displays a punctuate distribution pattern in chromatin despite lacking a strong DNA-binding domain. Previous studies suggest that the binding of HLCS to chromatin depends on DNA methylation. We tested the hypothesis that HLCS interacts physically with the DNA methyltransferase DNMT1 and the methyl CpG binding protein MeCP 2 to facilitate the binding of HLCS to chromatin, and that these interactions contribute toward the repression of long-terminal repeats (LTRs) by H3K9me marks. Co-immunoprecipitation and limited proteolysis assays provided evidence suggesting that HLCS interacts physically with both DNMT1 and MeCP 2. The abundance of H3K9me marks was 207% greater in the LTR15 locus in HLCS overexpression human embryonic kidney HEK293 cells compared with controls. This gain in H3K9me was inversely linked with a 87% decrease in mRNA coding for LTRs. Effects of HLCS abundance on LTR expression were abolished when DNA methylation marks were erased by treating cells with 5-azacytidine. We conclude that interactions between DNA methylation and HLCS are crucial for mediating gene repression by H3K9me, thereby providing evidence for epigenetic synergies between the protein biotin ligase HLCS and dietary methyl donors.

Original languageEnglish (US)
Pages (from-to)504-511
Number of pages8
JournalEpigenetics
Volume8
Issue number5
DOIs
StatePublished - May 2013

Keywords

  • Biotin
  • DNA methyl transferase
  • Holocarboxylase synthase
  • Long terminal repeats
  • Methyl CpG binding protein 2
  • Methylation
  • Repression

ASJC Scopus subject areas

  • Molecular Biology
  • Cancer Research

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