Hunchback is counter-repressed to regulate even-skipped stripe 2 expression in Drosophila embryos

PLoS Genet. 2018 Sep 7;14(9):e1007644. doi: 10.1371/journal.pgen.1007644. eCollection 2018 Sep.

Abstract

Hunchback is a bifunctional transcription factor that can activate and repress gene expression in Drosophila development. We investigated the regulatory DNA sequence features that control Hunchback function by perturbing enhancers for one of its target genes, even-skipped (eve). While Hunchback directly represses the eve stripe 3+7 enhancer, we found that in the eve stripe 2+7 enhancer, Hunchback repression is prevented by nearby sequences-this phenomenon is called counter-repression. We also found evidence that Caudal binding sites are responsible for counter-repression, and that this interaction may be a conserved feature of eve stripe 2 enhancers. Our results alter the textbook view of eve stripe 2 regulation wherein Hb is described as a direct activator. Instead, to generate stripe 2, Hunchback repression must be counteracted. We discuss how counter-repression may influence eve stripe 2 regulation and evolution.

Publication types

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

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Binding Sites / genetics
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Drosophila Proteins / genetics*
  • Drosophila Proteins / metabolism*
  • Drosophila melanogaster / genetics*
  • Drosophila melanogaster / growth & development
  • Embryo, Nonmammalian
  • Enhancer Elements, Genetic / genetics
  • Female
  • Gene Expression Regulation, Developmental*
  • Homeodomain Proteins / genetics*
  • Homeodomain Proteins / metabolism
  • Male
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism*

Substances

  • DNA-Binding Proteins
  • Drosophila Proteins
  • Homeodomain Proteins
  • Transcription Factors
  • cad protein, Drosophila
  • eve protein, Drosophila
  • hb protein, Drosophila