pitx3 defines an equivalence domain for lens and anterior pituitary placode

Sunit Dutta, Jens Erik Dietrich, Gudrun Aspöck, Rebecca D. Burdine, Alexander Schier, Monte Westerfield, Zoltán M. Varga

Research output: Contribution to journalArticle

96 Scopus citations

Abstract

Hedgehog signaling is required for formation and patterning of the anterior pituitary gland. However, the role of Hedgehog in pituitary precursor cell specification and subsequent placode formation is not well understood. We analyzed pituitary precursor cell lineages and find that pitx3 and distal-less3b (dlx3b) expression domains define lens and pituitary precursor positions. We show that pitx3 is required for pituitary pre-placode formation and cell specification, whereas dlx3b and dlx4b are required to restrict pituitary placode size. In smoothened mutant embryos that cannot transduce Hedgehog signals, median pituitary precursors are mis-specified and form an ectopic lens. Moreover, overexpression of sonic hedgehog (shh) blocks lens formation, and derivatives of lens precursors express genes characteristic of pituitary cells. However, overexpression of shh does not increase median pituitary placode size nor does it upregulate patched (ptc) expression in pituitary precursors during early somitogenesis. Our study suggests that by the end of gastrulation, pitx3-expressing cells constitute an equivalence domain of cells that can form either pituitary or lens, and that a non-Hedgehog signal initially specifies this placodal field. During mid-somitogenesis, Hedgehog then acts on the established median placode as a necessary and sufficient signal to specify pituitary cell types.

Original languageEnglish (US)
Pages (from-to)1579-1590
Number of pages12
JournalDevelopment
Volume132
Issue number7
DOIs
StatePublished - Apr 1 2005

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Developmental Biology

Keywords

  • Adenohypophysis
  • Anterior neural plate border
  • Cell fate specification
  • Cell lineage
  • Distal-less
  • Patched
  • Smoothened
  • Sonic hedgehog
  • Ventral ectoderm
  • Zebrafish

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