Krox20 hindbrain regulation incorporates multiple modes of cooperation between cis-acting elements

PLoS Genet. 2017 Jul 27;13(7):e1006903. doi: 10.1371/journal.pgen.1006903. eCollection 2017 Jul.


Developmental genes can harbour multiple transcriptional enhancers that act simultaneously or in succession to achieve robust and precise spatiotemporal expression. However, the mechanisms underlying cooperation between cis-acting elements are poorly documented, notably in vertebrates. The mouse gene Krox20 encodes a transcription factor required for the specification of two segments (rhombomeres) of the developing hindbrain. In rhombomere 3, Krox20 is subject to direct positive feedback governed by an autoregulatory enhancer, element A. In contrast, a second enhancer, element C, distant by 70 kb, is active from the initiation of transcription independent of the presence of the KROX20 protein. Here, using both enhancer knock-outs and investigations of chromatin organisation, we show that element C possesses a dual activity: besides its classical enhancer function, it is also permanently required in cis to potentiate the autoregulatory activity of element A, by increasing its chromatin accessibility. This work uncovers a novel, asymmetrical, long-range mode of cooperation between cis-acting elements that might be essential to avoid promiscuous activation of positive autoregulatory elements.

MeSH terms

  • Animals
  • Body Patterning / genetics
  • Chromatin / genetics
  • Early Growth Response Protein 1 / biosynthesis
  • Early Growth Response Protein 1 / genetics*
  • Enhancer Elements, Genetic*
  • Gene Expression Regulation, Developmental
  • Mice, Knockout
  • Mutation
  • Regulatory Elements, Transcriptional / genetics*
  • Rhombencephalon / growth & development*
  • Rhombencephalon / metabolism
  • Sequence Homology, Nucleic Acid


  • Chromatin
  • Early Growth Response Protein 1
  • Egr1 protein, mouse

Grant support

The P.C. laboratory was financed by the Institut National de la Recherche Médicale, the Centre National de la Recherche Scientifique, the Ministère de la Recherche et Technologie and the Fondation pour la Recherche Médicale (FRM). It has received support under the PIA launched by the French Government and implemented by the ANR, with the references: ANR-10-LABX-54 MEMOLIFE and ANR-11-IDEX-0001-02 PSL* Research University. The genomic platform of the IBENS is supported by France Génomique national infrastructure and funded as part of the Programme "Investissements d'Avenir" (PIA) managed by the Agence Nationale de la Recherche (ANR, contract ANR-10-INBS-0009). ET and JLM were supported by doctoral grants from Sorbonne Universités and by the FRM. PT is supported by doctoral grant from PSL Research University. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.