Project description:Here we investigate a functional role for SoxB1 transcription factors, Sox2 and Sox3, on the transient embryonic cell population, the neural plate border. We find through gain/loss-of-function studies necessary for neural plate border cells to become neural crest cells. and genomics experiments (ChIP-seq and RNA-seq) that SoxB1 transcription factors directly promote neural plate border formation. and that down-regulation of SoxB1 expression is
Project description:The epiblast of vertebrate embryos is comprised of neural and non-neural ectoderm, with the border territory at their intersection harbouring neural crest and cranial placode progenitors. Here we profile avian epiblast cells as a function of time using single-cell RNA-seq to define transcriptional changes in the emerging ‘neural plate border’. The results reveal gradual establishment of heterogeneous neural plate border signatures, including novel genes that we validate by fluorescent in situ hybridization. Developmental trajectory analysis shows that segregation of neural plate border lineages only commences at early neurulation, rather than at gastrulation as previously predicted. We find that cells expressing the prospective neural crest marker Pax7 contribute to multiple lineages, and a subset of premigratory neural crest cells shares a transcriptional signature with their border precursors. Together, our results suggest that cells at the neural plate border remain heterogeneous until early neurulation, at which time progenitors become progressively allocated toward defined lineages.
Project description:We describe a so far uncharacterized, embryonic and self-renewing Neural Plate Border Stem Cell (NBSC) population with the capacity to differentiate into central nervous and neural crest lineages. NBSCs can be obtained by neural transcription factor-mediated reprogramming (BRN2, SOX2, KLF4, and ZIC3) of human adult dermal fibroblasts and peripheral blood cells (induced Neural Plate Border Stem Cells, iNBSCs) or by directed differentiation from human induced pluripotent stem cells. Moreover, human (i)NBSCs share molecular and functional features with an endogenous NBSC population isolated from neural folds of E8.5 mouse embryos. Upon differentiation, iNBSCs give rise to either (1) radial glia-type stem cells, dopaminergic and serotonergic neurons, motoneurons, astrocytes, and oligodendrocytes or (2) cells from the neural crest lineage. Here we provide array-based expression data of primary mouse Neural Plate Border Stem Cells (pNBSCs) derived from E8.5 mouse embryos and radial glia-type stem cells and neural crest progenitors derived thereof. The data provided reveal that pNBSCs can be directed into defined neural cell types of the CNS- and neural crest lineage.
Project description:Neural crest development is orchestrated by a complex and still poorly understood gene regulatory network. Premigratory neural crest is induced at the lateral border of the neural plate by the combined action of signaling molecules and transcription factors such as AP2, Gbx2, Pax3 and Zic1. Among them, Pax3 and Zic1 are both necessary and sufficient to trigger a complete neural crest developmental program. However, their gene targets in the neural crest regulatory network remain unknown. Here, through a transcriptome analysis of frog microdissected neural border, we identified an extended gene signature for the premigratory neural crest, and we defined novel potential members of the regulatory network. This signature includes 34 novel genes, as well as 44 known genes expressed at the neural border. Using another microarray analysis which combined Pax3 and Zic1 gain-of-function and protein translation blockade, we uncovered 25 Pax3 and Zic1 direct targets within this signature. We demonstrated that the neural border specifiers Pax3 and Zic1 are direct upstream regulators of neural crest specifiers Snail1/2, Foxd3, Twist1, and Tfap2b. In addition, they may modulate the transcriptional output of multiple signaling pathways involved in neural crest development (Wnt, Retinoic Acid) through the induction of key pathway regulators (Axin2 and Cyp26c1). We also found that Pax3 could maintain its own expression through a positive autoregulatory feedback loop. These hierarchical inductions, feedback loops, and pathway modulation provide novel tools to understand the neural crest induction network. The transcriptomes of neural border samples (stage 14 and 18) were compared to the transcriptome of anterior neural fold (stage 18), early neural plate (stage 12), and animal cap explants (stage14) to identify genes expressed specifically in neural border samples. Tissue samples from Xenopus laevis embryos were dissected, then total RNA was extracted and hybridized on Affymetrix microarrays. Selected tissue samples encompass the neural crest at different stages of its induction (early neural plate at stage 12, neural border at stage 14, neural border at stage 18), as well as reference tissues (anterior neural fold at stage 18, a tissue that belongs to the neural border but does not produce neural crest, and animal cap grown until stage 14 that differentiates into epidermis).
Project description:Dorsal neural tube-derived retinoic acid promotes the end of neural crest production and transition into a definitive roof plate. Here we analyze how this impacts the segregation of central and peripheral lineages, a process essential for tissue patterning and function. Localized in-ovo inhibition of retinoic acid activity followed by single cell transcriptomics unraveled a comprehensive list of differentially expressed genes relevant to these processes. Importantly, progenitors co-expressed neural crest, roof plate and di1 interneuron markers indicating a failure in proper lineage segregation. Furthermore, we found that separation between roof plate and dI1 interneurons is mediated by Notch activity downstream of retinoic acid, highlighting their critical role in establishing the roof plate-dI1 boundary. Within the peripheral branch, where absence of retinoic acid resulted in neural crest production and emigration extending into the roof plate stage, sensory progenitors failed to separate from melanocytes leading to formation of a common glia-melanocyte cell with aberrant migratory patterns. Together, we uncover and characterize a molecular mechanism responsible for segregation of dorsal neural fates during development.
Project description:The neural crest is a dynamic progenitor cell population that arises at the border of neural and non-neural ectoderm. The inductive roles of FGF, Wnt, and BMP at the neural plate border are well established, but the signals required for subsequent neural crest development remain poorly characterized. Here, we conducted a screen in primary zebrafish embryo cultures for chemicals that decrease neural crest formation, as read out by crestin:EGFP expression. We found that the natural product caffeic acid phenethyl ester (CAPE) disrupts neural crest gene expression, migration, and melanocytic differentiation by reducing Sox10 activity. CAPE inhibits PI3K/Akt signaling specifically in FGF-stimulated cells, and neural crest defects in CAPE-treated embryos are suppressed by constitutively active Akt1. Inhibition of Akt activity by constitutively active PTEN similarly decreases crestin expression and Sox10 activity. Our study has identified Akt as a novel intracellular pathway required for neural crest development.
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.