A novel mammal-specific three partite enhancer element regulates node and notochord-specific Noto expression

PLoS One. 2012;7(10):e47785. doi: 10.1371/journal.pone.0047785. Epub 2012 Oct 22.

Abstract

The vertebrate organizer and notochord have conserved, essential functions for embryonic development and patterning. The restricted expression of developmental regulators in these tissues is directed by specific cis-regulatory modules (CRMs) whose sequence conservation varies considerably. Some CRMs have been conserved throughout vertebrates and likely represent ancestral regulatory networks, while others have diverged beyond recognition but still function over a wide evolutionary range. Here we identify and characterize a mammalian-specific CRM required for node and notochord specific (NNC) expression of NOTO, a transcription factor essential for node morphogenesis, nodal cilia movement and establishment of laterality in mouse. A 523 bp enhancer region (NOCE) upstream the Noto promoter was necessary and sufficient for NNC expression from the endogenous Noto locus. Three subregions in NOCE together mediated full activity in vivo. Binding sites for known transcription factors in NOCE were functional in vitro but dispensable for NOCE activity in vivo. A FOXA2 site in combination with a novel motif was necessary for NOCE activity in vivo. Strikingly, syntenic regions in non-mammalian vertebrates showed no recognizable sequence similarities. In contrast to its activity in mouse NOCE did not drive NNC expression in transgenic fish. NOCE represents a novel, mammal-specific CRM required for the highly restricted Noto expression in the node and nascent notochord and thus regulates normal node development and function.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Embryonic Stem Cells
  • Enhancer Elements, Genetic / genetics
  • Enhancer Elements, Genetic / physiology*
  • Gene Expression Regulation, Developmental / genetics
  • Gene Expression Regulation, Developmental / physiology*
  • Gene Regulatory Networks / genetics
  • Gene Regulatory Networks / physiology*
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism*
  • Mice
  • Microscopy, Fluorescence
  • Mutagenesis, Site-Directed
  • Notochord / embryology
  • Notochord / metabolism*
  • Organizers, Embryonic / embryology
  • Organizers, Embryonic / metabolism*
  • beta-Galactosidase

Substances

  • Homeodomain Proteins
  • Not protein, mouse
  • beta-Galactosidase

Grants and funding

This work was financially supported by funding in the “Normalverfahren” from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation), by the DFG funded Cluster of Excellence REBIRTH (From Regenerative Biology to Reconstructive Therapy) (AG), and by the EU FP7 CISSEM and the DFG collaborative research center SFB 488 (JW). Publication costs were supported by the DFG-Project “Open Access Publizieren.” The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.