Control of brain patterning by Engrailed paracrine transfer: a new function of the Pbx interaction domain.
Homeoproteins of the Engrailed family are involved in the patterning of mesencephalic boundaries through a mechanism classically ascribed to their transcriptional functions. In light of recent reports on the paracrine activity of homeoproteins, including Engrailed, we asked whether Engrailed intercellular transfer was also involved in brain patterning and boundary formation. Using time-controlled activation of Engrailed combined with tools that block its transfer, we show that the positioning of the diencephalic-mesencephalic boundary (DMB) requires Engrailed paracrine activity. Both zebrafish Eng2a and Eng2b are competent for intercellular transfer in vivo, but only extracellular endogenous Eng2b, and not Eng2a, participates in DMB positioning. In addition, disruption of the Pbx-interacting motif in Engrailed, known to strongly reduce the gain-of-function phenotype, also downregulates Engrailed transfer, thus revealing an unsuspected participation of the Pbx interaction domain in this pathway.
Université Paris Diderot, Sorbonne Paris Cité, Paris 75205, Cedex 13, France Center for Interdisciplinary Research in Biology (CIRB) - CNRS UMR 7241, INSERM U1050, Labex MemoLife, PSL Research University, Collège de France, Paris F-75005, France.
Christine
C
Rampon
Center for Interdisciplinary Research in Biology (CIRB) - CNRS UMR 7241, INSERM U1050, Labex MemoLife, PSL Research University, Collège de France, Paris F-75005, France.
Carole
C
Gauron
Center for Interdisciplinary Research in Biology (CIRB) - CNRS UMR 7241, INSERM U1050, Labex MemoLife, PSL Research University, Collège de France, Paris F-75005, France.
Thibault
T
Lin
Center for Interdisciplinary Research in Biology (CIRB) - CNRS UMR 7241, INSERM U1050, Labex MemoLife, PSL Research University, Collège de France, Paris F-75005, France École Normale Supérieure, Institute of Biology at the Ecole Normale Supérieure (IBENS), CNRS UMR8197, INSERM U1024, PSL Research University, Paris F-75005, France.
Francesca
F
Meda
Center for Interdisciplinary Research in Biology (CIRB) - CNRS UMR 7241, INSERM U1050, Labex MemoLife, PSL Research University, Collège de France, Paris F-75005, France.
Edmond
E
Dupont
Center for Interdisciplinary Research in Biology (CIRB) - CNRS UMR 7241, INSERM U1050, Labex MemoLife, PSL Research University, Collège de France, Paris F-75005, France.
Adrien
A
Cosson
Center for Interdisciplinary Research in Biology (CIRB) - CNRS UMR 7241, INSERM U1050, Labex MemoLife, PSL Research University, Collège de France, Paris F-75005, France École Normale Supérieure, Institute of Biology at the Ecole Normale Supérieure (IBENS), CNRS UMR8197, INSERM U1024, PSL Research University, Paris F-75005, France.
Eliane
E
Ipendey
Center for Interdisciplinary Research in Biology (CIRB) - CNRS UMR 7241, INSERM U1050, Labex MemoLife, PSL Research University, Collège de France, Paris F-75005, France.
Alice
A
Frerot
Ecole Normale Supérieure-PSL Research University, Département de Chimie, UMR 8640 CNRS-ENS-UPMC PASTEUR, 24, rue Lhomond, Paris 75005, France.
Isabelle
I
Aujard
Ecole Normale Supérieure-PSL Research University, Département de Chimie, UMR 8640 CNRS-ENS-UPMC PASTEUR, 24, rue Lhomond, Paris 75005, France.
Thomas
T
Le Saux
École Normale Supérieure, Institute of Biology at the Ecole Normale Supérieure (IBENS), CNRS UMR8197, INSERM U1024, PSL Research University, Paris F-75005, France Laboratoire de Physique Statistique, UMR CNRS-ENS 8550, Paris F-75005, France Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA 90095-1569, USA.
David
D
Bensimon
Ecole Normale Supérieure-PSL Research University, Département de Chimie, UMR 8640 CNRS-ENS-UPMC PASTEUR, 24, rue Lhomond, Paris 75005, France.
Ludovic
L
Jullien
Center for Interdisciplinary Research in Biology (CIRB) - CNRS UMR 7241, INSERM U1050, Labex MemoLife, PSL Research University, Collège de France, Paris F-75005, France École Normale Supérieure, Institute of Biology at the Ecole Normale Supérieure (IBENS), CNRS UMR8197, INSERM U1024, PSL Research University, Paris F-75005, France.
Michel
M
Volovitch
Université Paris Diderot, Sorbonne Paris Cité, Paris 75205, Cedex 13, France Center for Interdisciplinary Research in Biology (CIRB) - CNRS UMR 7241, INSERM U1050, Labex MemoLife, PSL Research University, Collège de France, Paris F-75005, France vriz@univ-paris-diderot.fr Alain.joliot@college-de-france.fr.
Sophie
S
Vriz
Center for Interdisciplinary Research in Biology (CIRB) - CNRS UMR 7241, INSERM U1050, Labex MemoLife, PSL Research University, Collège de France, Paris F-75005, France vriz@univ-paris-diderot.fr Alain.joliot@college-de-france.fr.
Alain
A
Joliot
D000818:Animals; D001921:Brain / Q000196:embryology* / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D015027:Zebrafish / Q000196:embryology* / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*; D000099266:Engrailed 2 Protein
D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; D029961:Zebrafish Proteins; C079428:en2a protein, zebrafish; D000099266:Engrailed 2 Protein
Diencephalic-mesencephalic boundary; Engrailed 2; Hexapeptide; Homeoprotein signalling