RING1B O-GlcNAcylation regulates gene targeting of polycomb repressive complex 1 in human embryonic stem cells

Julien Jean Pierre Maury1, Chadi A El Farran2, Daniel Ng3

  • 1Bioprocessing Technology Institute, Agency for Science, Technology and Research (A*STAR), 20 Biopolis Way, #06-01 Centros, 138668 Singapore; Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, 9 Engineering Drive 1, 117575 Singapore; Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, #08-01 Proteos, 138673 Singapore.

Stem Cell Research
|June 24, 2015
PubMed

Insights

O-linked-N-acetylglucosamine (O-GlcNAc) modifies RING1B, an epigenetic regulator crucial for human embryonic stem cell (hESC) pluripotency and differentiation. Decreased O-GlcNAc on RING1B during differentiation may promote neuron development.

Area of Science:

  • Epigenetics
  • Stem Cell Biology
  • Post-Translational Modifications

Background:

  • O-linked-N-acetylglucosamine (O-GlcNAc) is a dynamic post-translational modification regulating numerous cellular processes.
  • O-GlcNAc's role in human embryonic stem cell (hESC) differentiation is emerging, but specific regulatory proteins remain unidentified.

Purpose of the Study:

  • To identify O-GlcNAc-modified proteins involved in hESC regulation.
  • To investigate the function of O-GlcNAc modification on RING1B during hESC differentiation.

Main Methods:

  • Identification of O-GlcNAc proteins in hESCs.
  • Site-directed mutagenesis to map O-GlcNAc sites on RING1B.
  • Chromatin immunoprecipitation sequencing (ChIP-seq) to analyze RING1B binding.
  • Analysis of O-GlcNAc levels during differentiation.

Main Results:

  • hnRNP K, HP1γ, and RING1B were identified as O-GlcNAc-modified proteins in hESCs.
  • Specific residues T(250)/S(251) and S(278) on RING1B are O-GlcNAcylated, with T(250)/S(251) O-GlcNAcylation decreasing during differentiation.
  • O-GlcNAc modification influences RING1B-DNA binding, with distinct genomic enrichment patterns observed for modified versus unmodified RING1B near cell cycle and neuronal genes.

Conclusions:

  • O-GlcNAc dynamically regulates RING1B, a key component of the Polycomb Repressive Complex 1 (PRC1).
  • The decrease in RING1B O-GlcNAcylation during hESC differentiation may facilitate PRC1's target switching, promoting neuronal differentiation.
  • O-GlcNAc modification of RING1B represents a novel regulatory mechanism contributing to hESC pluripotency maintenance and differentiation pathways.

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