Tbx2/3 is an essential mediator within the brachyury gene network during Ciona notochord development

Diana S. José-Edwards, Izumi Oda-Ishii, Yutaka Nibu, Anna Di Gregorio

Research output: Contribution to journalArticlepeer-review


T-box genes are potent regulators of mesoderm development in many metazoans. In chordate embryos, the T-box transcription factor Brachyury (Bra) is required for specification and differentiation of the notochord. In some chordates, including the ascidian Ciona, members of the Tbx2 subfamily of T-box genes are also expressed in this tissue; however, their regulatory relationships with Bra and their contributions to the development of the notochord remain uncharacterized. We determined that the notochord expression of Ciona Tbx2/3 (Ci-Tbx2/3) requires Ci-Bra, and identified a Ci-Tbx2/3 notochord CRM that necessitates multiple Ci-Bra binding sites for its activity. Expression of mutant forms of Ci-Tbx2/3 in the developing notochord revealed a role for this transcription factor primarily in convergent extension. Through microarray screens, we uncovered numerous Ci-Tbx2/3 targets, some of which overlap with known Ci-Bra-downstream notochord genes. Among the Ci-Tbx2/3 notochord targets are evolutionarily conserved genes, including caspases, lineage-specific genes, such as Noto4, and newly identified genes, such as MLKL. This work sheds light on a large section of the notochord regulatory circuitry controlled by T-box factors, and reveals new components of the complement of genes required for the proper formation of this structure.

Original languageEnglish (US)
Pages (from-to)2422-2433
Number of pages12
JournalDevelopment (Cambridge)
Issue number11
StatePublished - Jun 1 2012


  • Brachyury
  • Ciona
  • Notochord

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology


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