Variable requirements for DNA-binding proteins at polycomb-dependent repressive regions in human HOX clusters

Mol Cell Biol. 2013 Aug;33(16):3274-85. doi: 10.1128/MCB.00275-13. Epub 2013 Jun 17.

Abstract

Polycomb group (PcG)-mediated repression is an evolutionarily conserved process critical for cell fate determination and maintenance of gene expression during embryonic development. However, the mechanisms underlying PcG recruitment in mammals remain unclear since few regulatory sites have been identified. We report two novel prospective PcG-dependent regulatory elements within the human HOXB and HOXC clusters and compare their repressive activities to a previously identified element in the HOXD cluster. These regions recruited the PcG proteins BMI1 and SUZ12 to a reporter construct in mesenchymal stem cells and conferred repression that was dependent upon PcG expression. Furthermore, we examined the potential of two DNA-binding proteins, JARID2 and YY1, to regulate PcG activity at these three elements. JARID2 has differential requirements, whereas YY1 appears to be required for repressive activity at all 3 sites. We conclude that distinct elements of the mammalian HOX clusters can recruit components of the PcG complexes and confer repression, similar to what has been seen in Drosophila. These elements, however, have diverse requirements for binding factors, which, combined with previous data on other loci, speaks to the complexity of PcG targeting in mammals.

Publication types

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

MeSH terms

  • Animals
  • Cells, Cultured
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Gene Expression Regulation, Developmental*
  • Genes, Homeobox
  • Homeodomain Proteins / genetics*
  • Humans
  • Mesenchymal Stem Cells / metabolism*
  • Multigene Family*
  • Polycomb Repressive Complex 2 / genetics
  • Polycomb Repressive Complex 2 / metabolism
  • Polycomb-Group Proteins / genetics
  • Polycomb-Group Proteins / metabolism*
  • Regulatory Elements, Transcriptional
  • Transcription, Genetic

Substances

  • DNA-Binding Proteins
  • Homeodomain Proteins
  • JARID2 protein, human
  • Polycomb-Group Proteins
  • Polycomb Repressive Complex 2