Altering cell fates in sea urchin embryos by overexpressing SpOtx, an orthodenticle-related protein

Chai An Mao, Athula H. Wikramanayake, Lin Gan, Chin Kai Chuang, Robert G. Summers, William H. Klein

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


While many general features of cell fate specification in the sea urchin embryo are understood, specific factors associated with these events remain unidentified. SpOtx, an orthodenticle-related protein, has been implicated as a transcriptional activator of the aboral ectoderm-specific Spec2a gene. Here, we present evidence that SpOtx has the potential to alter cell fates. SpOtx was found in the cytoplasm of early cleavage stage embryos and was translocated into nuclei between the 60- and 120-cell stage, coincident with Spec gene activation. Eggs injected with SpOtx mRNA developed into epithelial balls of aboral ectoderm suggesting that SpOtx redirected nonaboral ectoderm cells to an aboral ectoderm fate. At least three distinct domains on SpOtx, the homeobox and regions in the N-terminal and C-terminal halves of the protein, were required for the morphological alterations. These same N-terminal and C-terminal regions were shown to be transactivation domains in a yeast transactivation assay, indicating that the biological effects of overexpressing SpOtx were due to its action as a transcription factor. Our results suggest that SpOtx is involved in aboral ectoderm differentiation by activating aboral ectoderm-specific genes and that modulating its expression can lead to changes in cell fate.

Original languageEnglish (US)
Pages (from-to)1489-1498
Number of pages10
Issue number5
StatePublished - 1996
Externally publishedYes


  • Embryo development
  • Homeobox protein
  • Orthodenticle/Otx-genes
  • Sea urchin
  • SpOtx

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology


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