1. Cell Biology
  2. Developmental Biology
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Early asymmetric cues triggering the dorsal/ventral gene regulatory network of the sea urchin embryo

  1. Vincenzo Cavalieri  Is a corresponding author
  2. Giovanni Spinelli
  1. University of Palermo, Italy
Research Article
  • Cited 23
  • Views 1,561
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Cite this article as: eLife 2014;3:e04664 doi: 10.7554/eLife.04664

Abstract

Dorsal/ventral (DV) patterning of the sea urchin embryo relies on a ventrally-localized organizer expressing Nodal, a pivotal regulator of the DV gene regulatory network. However, the inceptive mechanisms imposing the symmetry-breaking are incompletely understood. In Paracentrotus lividus, the Hbox12 homeodomain-containing repressor is expressed by prospective dorsal cells, spatially facing and preceding the onset of nodal transcription. We report that Hbox12-misexpression provokes DV abnormalities, attenuating nodal and nodal-dependent transcription. Reciprocally, impairing hbox12 function disrupts DV polarity by allowing ectopic expression of nodal. Clonal loss-of-function, inflicted by blastomere transplantation or gene-transfer assays, highlights that DV polarization requires Hbox12 action in dorsal cells. Remarkably, the localized knock-down of nodal restores DV polarity of embryos lacking hbox12 function. Finally, we show that hbox12 is a dorsal-specific negative modulator of the p38-MAPK activity, which is required for nodal expression. Altogether, our results suggest that Hbox12 function is essential for proper positioning of the DV organizer.

Article and author information

Author details

  1. Vincenzo Cavalieri

    Department of Biological, Chemical and Pharmaceutical Sciences and Technologies, University of Palermo, Palermo, Italy
    For correspondence
    vincenzo.cavalieri@unipa.it
    Competing interests
    The authors declare that no competing interests exist.
  2. Giovanni Spinelli

    Department of Biological, Chemical and Pharmaceutical Scciences and Technologies, University of Palermo, Palermo, Italy
    Competing interests
    The authors declare that no competing interests exist.

Reviewing Editor

  1. Robb Krumlauf, Stowers Institute for Medical Research, United States

Publication history

  1. Received: September 9, 2014
  2. Accepted: December 1, 2014
  3. Accepted Manuscript published: December 2, 2014 (version 1)
  4. Version of Record published: December 23, 2014 (version 2)

Copyright

© 2014, Cavalieri & Spinelli

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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