Pitx genes in Tunicates provide new molecular insight into the evolutionary origin of pituitary

Lionel Christiaen, Paolo Burighel, William C. Smith, Philippe Vernier, Franck Bourrat, Jean Stéphane Joly

Research output: Contribution to journalArticlepeer-review


We have initiated a project aimed at documenting molecular and cellular changes underlying the emergence of the hypothalamo-hypophyseal axis in Chordates. Considering the phylogenetic position of Tunicates and the 'pan-hypophyseal' expression pattern of Pitx genes in Vertebrate pituitary, we searched for a Pitx-related homeobox gene in the ascidian Ciona intestinalis, and identified Ci-Pitx (Ciona intestinalis Pituitary homeobox gene). We also isolated Cs-Pitx and Bs-Pitx, the Ci-Pitx respective counterparts of Ciona savignyi and Botryllus schlosseri, two other Tunicate species. Ci-Pitx mRNA encodes a putative protein exhibiting the diagnostic K50-Paired-class homeodomain and a conserved C-terminal Aristaless domain. Embryonic expression pattern of Ci-Pitx revealed a conserved expression domain in the anterior neural ridge and subsequently in the pharyngeal primordium, defined in Vertebrates as the stomodeal ectomere, which encompasses the presumptive pituitary territory. This shows that expression at early steps of pituitary development is a feature of Pitx-related genes that was already present in the last common ancestor of Chordates.

Original languageEnglish (US)
Pages (from-to)107-113
Number of pages7
Issue number1-2
StatePublished - Apr 3 2002


  • Anterior neural ridge
  • Aristaless domain
  • Ascidian
  • Hypophysis
  • Neural complex
  • Paired-class homeodomain
  • Stomodeum

ASJC Scopus subject areas

  • Genetics


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