Evolution of the interaction between Hox genes and a downstream target

Curr Biol. 1998 May 7;8(10):587-90. doi: 10.1016/s0960-9822(98)70228-3.


Segmental identities along the insect body depend on the activities of Hox genes [1,2]. In Drosophila melanogaster, one well-studied Hox regulatory target is Distal-less (Dll), which is required for the development of distal limb structures [3]. In abdominal segments, Dll transcription is prevented when Hox proteins of the Bithorax Complex (BX-C) bind to cis-regulatory elements upstream of the Dll transcription start site [4,5]. Previous evolutionary comparisons of gene expression patterns suggest that this direct repression is conserved between Diptera and Lepidoptera, but is absent in the Crustacea [6,7]. We examined gene expression patterns in three orders of hexapods, all of which develop abdominal appendages, in order to determine when the strong repressive interaction between BX-C proteins and Dll appeared during evolution. In each of the species examined, Dll expression was initiated in abdominal cells despite the presence of high levels of BX-C proteins. It appears that the strong repressive effects of BX-C proteins on Dll expression arose relatively late in insect evolution. We suggest that the regulatory interaction between the BX-C genes and Dll has evolved within the hexapods in a complex, segment-specific manner.

MeSH terms

  • Animals
  • Biological Evolution
  • Coleoptera / genetics
  • DNA-Binding Proteins / genetics*
  • Drosophila Proteins*
  • Drosophila melanogaster / genetics
  • Gene Expression
  • Genes, Homeobox*
  • Genes, Insect*
  • Homeodomain Proteins / genetics*
  • Insect Proteins / genetics*
  • Insecta / genetics
  • Nuclear Proteins*
  • Orthoptera / genetics
  • Transcription Factors*


  • DNA-Binding Proteins
  • Drosophila Proteins
  • Homeodomain Proteins
  • Insect Proteins
  • Nuclear Proteins
  • Transcription Factors
  • Ubx protein, Drosophila
  • abd-A protein, Drosophila