Transcriptional silencing by the Polycomb protein in Drosophila embryos

EMBO J. 1995 Mar 15;14(6):1209-20.


Polycomb group (Pc-G) proteins act to keep homeotic genes stably and heritably silenced during Drosophila development. Here, it is shown that Polycomb (Pc), one of the Pc-G proteins, acts as a transcriptional silencer in Drosophila embryos if tethered to reporter genes by the DNA binding domain of GAL4 (i.e. as a GAL-Pc fusion protein). The results suggest that silencing by GAL-Pc requires the C-terminal portion of Pc, but not the chromodomain. If a pulse of Gal-Pc is provided, synthetic reporter genes are repressed, though only transiently. In contrast, reporter genes containing homeotic gene sequences remain stably and heritably silenced in a Pc-G gene-dependent fashion, even when GAL-Pc is no longer present. This implies that GAL-Pc recruits Pc-G proteins to DNA and suggests that maintenance of silencing requires the anchoring of Pc-G proteins to specific cis-regulatory sequences present in homeotic genes. The extent of DNA over which the Pc-G machinery acts is quite selective, as silencing established on one enhancer does not necessarily 'spread' to a juxtaposed synthetic enhancer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP-Binding Cassette Transporters*
  • Animals
  • Base Sequence
  • Crosses, Genetic
  • DNA / metabolism
  • DNA-Binding Proteins / genetics
  • Drosophila / embryology
  • Drosophila Proteins*
  • Enhancer Elements, Genetic / genetics
  • Eye Proteins*
  • Fungal Proteins / genetics
  • Gene Expression Regulation, Developmental / physiology*
  • Genes, Homeobox / genetics
  • Genes, Reporter / genetics
  • Homeodomain Proteins*
  • Insect Hormones / genetics
  • Juvenile Hormones / genetics
  • Juvenile Hormones / physiology
  • Models, Genetic
  • Molecular Sequence Data
  • Point Mutation / genetics
  • Polycomb Repressive Complex 1
  • Promoter Regions, Genetic / genetics
  • Proteins / metabolism
  • Proteins / physiology*
  • Recombinant Fusion Proteins / biosynthesis
  • Recombinant Fusion Proteins / physiology*
  • Saccharomyces cerevisiae Proteins*
  • Transcription Factors*
  • Transcription, Genetic / physiology*


  • ATP-Binding Cassette Transporters
  • DNA-Binding Proteins
  • Drosophila Proteins
  • Eye Proteins
  • Fungal Proteins
  • GAL4 protein, S cerevisiae
  • Homeodomain Proteins
  • Insect Hormones
  • Juvenile Hormones
  • Pc protein, Drosophila
  • Proteins
  • Recombinant Fusion Proteins
  • Saccharomyces cerevisiae Proteins
  • Transcription Factors
  • Ubx protein, Drosophila
  • hb protein, Drosophila
  • w protein, Drosophila
  • DNA
  • Polycomb Repressive Complex 1