Project description:Neural crest cells are multipotent cells that delaminate from the neuroepithelium, migrating throughout the embryo. Aberrant migration causes developmental defects. Animal models are improving our understanding of neural crest anomalies, but in vivo migration behaviours are poorly understood. Here, we demonstrate that murine neural crest cells display actin-based lamellipodia and filopodia in vivo. Using neural crest-specific knockouts or inhibitors, we show that the serine-threonine kinase Glycogen Synthase Kinase-3 (GSK3), and the cytoskeletal regulator Lamellipodin (Lpd), are required for lamellipodia formation whilst preventing focal adhesion maturation. Lpd is a novel substrate of GSK3 and phosphorylation of Lpd favours interactions with the Scar/WAVE complex (lamellipodia formation) at the expense of VASP and Mena interactions (adhesion maturation and filopodia formation). This improved understanding of cytoskeletal regulation in mammalian neural crest migration has general implications for neural crest anomalies and cancer.
Project description:We utilized quantitative analyses of the proteome, transcriptome, and ubiquitinome to study how ubiquitination and NEDD4 control neural crest cell survival and stem-cell-like properties. We report 276 novel NEDD4 targets in neural crest cells and show that loss of NEDD4 leads to a striking global reduction in specific ubiquitin lysine linkages.
Project description:Neural crest cells exemplify cellular diversification from a multipotent progenitor population. However, the full sequence of molecular choices governing the emergence of neural crest heterogeneity from the ectoderm remains elusive. Gene regulatory networks govern these steps of embryonic development and cell specification towards definitive neural crest. Here, we combine ultra-dense single cell transcriptomes with machine-learning strategies and experimental validation to provide a comprehensive gene regulatory network driving vertebrate neural crest fate diversification, from induction to early migration stages. Transcription factor connectome and bifurcation analyses demonstrate emergence of early neural crest fates at the neural plate stage, alongside an unbiased multipotent neural crest lineage persisting until after epithelial-mesenchymal transition. We also define a new and transient neural border zone state, preceding choice between neural crest and placodes during gastrulation. Theis combination of experimental tests, with Machine Learning broadly applicable to single cell transcriptomics, deciphers the circuits driving cranial and vagal neural crest formation and provides a general model for investigating vertebrate GRNs in development, evolution and disease.
Project description:Human neural crest cell development progresses via a pre-neural border (pNB) cell state that precedes the induction of the neurectoderm and the neural border. Here, we identify a set of pNB gene candidates, including forkhead box B1 (FOXB1), and their associated enhancers, that are rapidly activated by β-catenin-mediated signaling during human embryonic stem (ES) cell differentiation towards neural crest cells. FOXB1 simultaneously maintains neuroectoderm competency and controls the timing of differentiating ES cells to acquire neural crest fate by directly targeting key neural crest and neural progenitor loci in a context-dependent manner. Notably, the transient expression of FOXB1 in pre-neural crest cells also establishes autonomic neurogenic potential in mature neural crest cells, likely via its regulation of the expression of ASCL1, a master regulator of autonomic neurons. Altogether, our data implicates pNB cell state as the missing link bridging the exit of pluripotency to the acquisition of neural crest fate and its diverse ecto-mesenchymal differentiation potentials.