Abstract
The hindbrain transcription factors Phox2b and Egr2 (also known as Krox20) are linked to the development of the autonomic nervous system and rhombomere-related regulation of breathing, respectively. Mutations in these proteins can lead to abnormal breathing behavior as a result of an alteration in an unidentified neuronal system. We characterized a bilateral embryonic parafacial (e-pF) population of rhythmically bursting neurons at embryonic day (E) 14.5 in mice. These cells expressed Phox2b, were derived from Egr2-expressing precursors and their development was dependent on the integrity of the Egr2 gene. Silencing or eliminating the e-pF oscillator, but not the putative inspiratory oscillator (preBötzinger complex, preBötC), led to an abnormally slow rhythm, demonstrating that the e-pF controls the respiratory rhythm. The e-pF oscillator, the only one active at E14.5, entrained and then coupled with the preBötC, which emerged independently at E15.5. These data establish the dual organization of the respiratory rhythm generator at the time of its inception, when it begins to drive fetal breathing.
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Acknowledgements
We thank J.F. Brunet and C. Goridis for comments on the manuscript and the Phox2b antibody, and K. Kullander for VGlut2 mutant mice. This work benefited from the facilities and expertise of the Imagif Cell Biology Unit of the Gif campus. This work was supported by the Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale (M.T.-B.) and ANR grant ANR-07-Neuro-007-01 (G.F.).
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M.T.-B. and G.F. designed, performed research and analyzed data, M.K. carried out immunostaining on Egr2 mutants and N.W. performed pharmacological treatments at E15.5. J.C. and P.C. helped with interpreting results and G.F. wrote the manuscript.
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Thoby-Brisson, M., Karlén, M., Wu, N. et al. Genetic identification of an embryonic parafacial oscillator coupling to the preBötzinger complex. Nat Neurosci 12, 1028–1035 (2009). https://doi.org/10.1038/nn.2354
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DOI: https://doi.org/10.1038/nn.2354
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