A Polycomb and GAGA dependent silencer adjoins the Fab-7 boundary in the Drosophila bithorax complex

Genetics. 1997 Aug;146(4):1365-80. doi: 10.1093/genetics/146.4.1365.

Abstract

The homeotic genes of the Drosophila bithorax complex are controlled by a large cis-regulatory region that ensures their segmentally restricted pattern of expression. A deletion that removes the Frontabdominal-7 cis-regulatory region (Fab-7') dominantly transforms parasegment 11 into parasegment 12. Previous studies suggested that removal of a domain boundary element on the proximal side of Fab-7' is responsible for this gain-of-function phenotype. In this article we demonstrate that the Fab-7' deletion also removes a silencer element, the iab-7 PRE, which maps to a different DNA segment and plays a different role in regulating parasegment-specific expression patterns of the Abd-B gene. The iab-7 PRE mediates pairing-sensitive silencing of mini-white, and can maintain the segmentally restricted expression pattern of a BXD, Ubx/lacZ reporter transgene. Both silencing activities depend upon Polycomb Group proteins. Pairing-sensitive silencing is relieved by removing the transvection protein Zeste, but is enhanced in a novel pairing-independent manner by the zeste' allele. The iab-7 PRE silencer is contained within a 0.8-kb fragment that spans a nuclease hypersensitive site, and silencing appears to depend on the chromatin remodeling protein, the GAGA factor.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alleles
  • Animals
  • Chromatin / genetics
  • Crosses, Genetic
  • DNA / genetics
  • DNA-Binding Proteins / genetics
  • Drosophila / embryology
  • Drosophila / genetics*
  • Drosophila / growth & development*
  • Drosophila Proteins*
  • Eye Color / genetics
  • Female
  • Gene Deletion
  • Gene Expression Regulation, Developmental
  • Genes, Homeobox*
  • Genes, Insect*
  • Genetic Complementation Test
  • Heterozygote
  • Homeodomain Proteins / genetics
  • Homozygote
  • Insect Proteins / genetics
  • Male
  • Mutation
  • Polycomb Repressive Complex 1
  • Transcription Factors / genetics

Substances

  • Chromatin
  • DNA-Binding Proteins
  • Drosophila Proteins
  • Homeodomain Proteins
  • Insect Proteins
  • Pc protein, Drosophila
  • Transcription Factors
  • Trl protein, Drosophila
  • z protein, Drosophila
  • DNA
  • Polycomb Repressive Complex 1