DS0402 - Décryptage des fonctions biologiques élémentaires et de leur intégration

Novel Challenges in the Neural Crest Early Gene Regulatory Network. – CRESTNETMETABO

Submission summary

Vertebrate development is orchestrated by complex gene regulatory networks (GRNs), which remain largely unexplored. Redundancy within protein families, paralogous genes swapping across species and fail-safe mechanisms complicate these networks establishment, beyond the technical difficulties linked to each model system. Despite these challenges, establishing these networks and understanding their conserved and species-specific aspects will open avenues to model normal development and congenital disorders. Moreover, the detailed knowledge of these GRNs is a prerequisite to a supervised control of stem cell programming into chosen lineages.

Our focus is the early GRN controlling neural crest (NC) induction and its epithelium-to-mesenchyme transition (EMT). The NC is a cell population specific to vertebrate embryos, which gives rise to peripheral neurons and glia, pigment cells, and other cell lineages, including craniofacial mesenchyme and skeleton. Numerous human congenital disorders are linked to defects in NC development. The NC network, a paradigm for vertebrate GRNs, is divided into sequential steps: induction, EMT, migration and differentiation. Our previous work has provided a scaffold for the early steps of this GRN (Monsoro-Burq & al, Development 2003; Dev. Cell 2005; De Crozé & al, PNAS 2011; Milet & al, PNAS 2013).

In this proposal, our consortium gathers synergistic expertise in non-mammalian and mammalian NC development and bioinformatics to tackle the challenge of building a comprehensive GRN in NC induction and EMT that will include common and species-specific features.

In the first objective, we focus on NC induction by Pax3 transcription factor (or its paralog Pax7) and its partners Zic1 / Msx1, based on two observations. Firstly, we have shown that Pax3 is at the core of NC induction in frogs, including cephalic, cardiac and trunk NC. Pax3, in cooperation with these partners, is sufficient to trigger multipotent and functional NC from pluripotent cells (PNAS 2013). Secondly, in vivo, Pax3/7 is required for trunk and cardiac NC both in aquatic species (Dev. Cell 2005), in avian (Bronner Lab, Nature 2006) and mouse embryos (Splotch mutant, embryonic lethal, Relaix lab mouse knock-in lines). In contrast, data from mouse and human Pax3/7 mutants also suggest that cephalic NC formation is initiated in these mutant mammals, with defects arising post-migration (Relaix lab, Dev Cell 2015). In human, Waardenburg syndrome patients (usually heterozygous PAX3 mutation) present congenital deafness, craniofacial dysmorphisms and other symptoms linked to defective NC development. We will explore conserved and alternative induction mechanisms, comparing cephalic, cardiac and trunk NC in mammals and non-mammalian vertebrates.

Using next-generation sequencing (RNAseq, ChIPseq), bioinformatics, applied to functional validation developed in frog and mouse (Partners 1-2-4), we will construct and compare the GNRs in wild-type and Pax3/7 loss of function contexts during vertebrate early NC development. Moreover, the current NC GRN, is not only fragmental, but is mainly limited to signaling molecules and a few target transcription factors. Our preliminary large-scale data have uncovered metabolism regulators important for neural crest induction / EMT, downstream of Pax3 (Nature Communications 2015 and unpublished). This indicates that Pax3 may link the NC-GRN to cell homeostasis as observed in cancer. Our second objective will analyze the molecular mechanisms of these novel regulations. For both objectives, our project involves the generation large-scale datasets in parallel to their in-depth functional validation in animal models in vivo or in cell models. We will also develop interfaces to exchange such data within the developmental biology community and maximize their impact. Our project will be the first comprehensive approach of neural crest induction and EMT connecting animal models and Pax3-linked human neurocristopathy.

Project coordination

Anne-Hélène MONSORO-BURQ (INSTITUT CURIE - SECT DE RECHERCHE)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

IC UMR3347 U1021 INSTITUT CURIE - SECT DE RECHERCHE
ARMINES (CBIO) ARMINES Centre de Bio-informatique de Mines ParisTech
INSERM U955 INSERM / IMRB U955,
KCL KING'S COLLEGE LONDON

Help of the ANR 450,000 euros
Beginning and duration of the scientific project: - 48 Months

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