The snail repressor establishes a muscle/notochord boundary in the Ciona embryo

Shigeki Fujiwara, Joseph C. Corbo, Michael Levine

Research output: Contribution to journalArticlepeer-review

90 Scopus citations


Previous studies have identified a minimal 434 bp enhancer from the promoter region of the Ciona Brachyury gene (Ci-Bra), which is sufficient to direct a notochord-specific pattern of gene expression. Here we present evidence that a Ciona homolog of snail (Ci-sna) encodes a repressor of the Ci-Bra enhancer in the tail muscles. DNA-binding assays identified four Ci-Sna-binding sites in the Ci-Bra enhancer, and mutations in these sites cause otherwise normal Ci-Bra/lacZ transgenes to be misexpressed in ectopic tissues, particularly the tail muscles. Selective misexpression of Ci-sna using a heterologous promoter results in the repression of Ci-Bra/lacZ transgenes in the notochord. Moreover, the conversion of the Ci-Sna repressor into an activator results in the ectopic induction of Ci-Bra/lacZ transgenes in the muscles, and also causes an intermixing of notochord and muscle cells during tail morphogenesis. These results suggest that Ci-Sna functions as a boundary repressor, which subdivides the mesoderm into separate notochord and tail muscle lineages.

Original languageEnglish (US)
Pages (from-to)2511-2520
Number of pages10
Issue number13
StatePublished - Jul 1998
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Developmental Biology


  • Ci-Bra enhancer
  • Ciona
  • Muscle
  • Notochord
  • Repressor
  • Snail


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