Anterior repression of a drosophila stripe enhancer requires three position-specific mechanisms

Luiz Paulo Maura Andrioli, Vikram Visisht, Ekaterina Theodosopoulou, Adam Oberstein, Stephen Small

Research output: Contribution to journalArticle

Abstract

The striped expression pattern of the pair-rule gene even skipped (eve) is established by five stripe-specific enhancers, each of which responds in a unique way to gradients of positional information in the early Drosophila embryo. The enhancer for eve stripe 2 (eve 2) is directly activated by the morphogens Bicoid (Bcd) and Hunchback (Hb). As these proteins are distributed throughout the anterior half of the embryo, formation of a single stripe requires that enhancer activation is prevented in all nuclei anterior to the stripe 2 position. The gap gene giant (gt) is involved in a repression mechanism that sets the anterior stripe border, but genetic removal of gt (or deletion of Gt-binding sites) causes stripe expansion only in the anterior subregion that lies adjacent to the stripe border. We identify a well-conserved sequence repeat, (GTTT)4, which is required for repression in a more anterior subregion. This site is bound specifically by Sloppy-paired 1 (Slp1), which is expressed in a gap gene-like anterior domain. Ectopic Slp1 activity is sufficient for repression of stripe 2 of the endogenous; eve gene, but is not required, suggesting that it is redundant with other anterior factors. Further genetic analysis suggests that the (GTTT)4-mediated mechanism is independent of the Gt-mediated mechanism that sets the anterior stripe border, and suggests that a third mechanism, downregulation of Bcd activity by Torso, prevents activation near the anterior tip. Thus, three distinct mechanisms are required for anterior repression of a single eve enhancer, each in a specific position. Ectopic Slp1 also represses eve stripes 1 and 3 to varying degrees, and the eve 1 and eve 3+7 enhancers each contain GTTT repeats similar to the site in the eve 2 enhancer. These results suggest a common mechanism for preventing anterior activation of three different eve enhancers.

Original languageEnglish (US)
Pages (from-to)4931-4940
Number of pages10
JournalDevelopment
Volume129
Issue number21
StatePublished - Nov 2002

Keywords

  • Embryogenesis
  • Enhancer
  • Even-Skipped
  • Patterning
  • Repression

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology

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    Andrioli, L. P. M., Visisht, V., Theodosopoulou, E., Oberstein, A., & Small, S. (2002). Anterior repression of a drosophila stripe enhancer requires three position-specific mechanisms. Development, 129(21), 4931-4940.