Project description:The epithelial-to-mesenchymal transition (EMT) and migration of cranial neural crest cells are critical processes that occur in the early embryo that permit proper craniofacial patterning. Disruptions in these processes not only impair development but also lead to various diseases, underscoring the need for their detailed understanding at the molecular level. The chick embryo has served historically as an excellent model for human embryonic development. While chick cranial neural crest cell EMT and migration have been characterized at the transcript level, studies at the protein level—to allow direct measurement of the active players—have not been undertaken to date. In this study, we applied mass spectrometry (MS)-based proteomics to establish a deep proteomics profile of the midbrain region during early embryonic development. We developed a proteomics method combining optimal lysis conditions and offline fractionation with nanoflow liquid chromatography coupled to high-resolution MS to analyze the tissue from this region, which identified >5,900 proteins involved in key pathways related to neural crest cell EMT and migration such as signaling, proteolysis/extracellular matrix (ECM), and transcriptional regulation. This study offers valuable insight into important developmental processes occurring in the midbrain region and demonstrates the utility of proteomics for characterization of various tissues during chick embryogenesis.
Project description:Developmental potential is progressively restricted after germ layer specification during gastrulation. However, cranial neural crest cells challenge this paradigm, as they develop from anterior ectoderm yet give rise to both mesodermal derivatives of the craniofacial skeleton and ectodermal derivatives of the peripheral nervous system. How cranial neural crest cells differentiate into multiple lineages is poorly understood. Here, we demonstrate that cranial neural crest cells possess a transient state of increased chromatin accessibility; and that the earliest premigratory neural crest are biased towards either a neuronal or ectomesenchymal fate, with each lineage expressing distinct factors from the pluripotent state. We profile the spatiotemporal emergence of each neural crest population and demonstrate that the ectomesenchymal lineage forms prior to the neuronal progenitors. Expression of the pluripotency microRNA family miR-302 is maintained in cranial neural crest cells and genetic deletion leads to precocious specification of the ectomesenchymal lineage. We find that miR-302 directly targets Sox9 to slow the timing of ectomesenchyme induction and regulates multiple genes involved in chromatin condensation to maintain accessibility for neuronal differentiation. Loss of mir-302 results in reduced chromatin accessibility in the neuronal progenitor lineage of neural crest and a reduction in peripheral neuron differentiation. Our findings reveal a post-transcriptional mechanism governed by miRNAs from pluripotency as an important mechanism to expand developmental potential of cranial neural crest.
Project description:Developmental potential is progressively restricted after germ layer specification during gastrulation. However, cranial neural crest cells challenge this paradigm, as they develop from anterior ectoderm yet give rise to both mesodermal derivatives of the craniofacial skeleton and ectodermal derivatives of the peripheral nervous system. How cranial neural crest cells differentiate into multiple lineages is poorly understood. Here, we demonstrate that cranial neural crest cells possess a transient state of increased chromatin accessibility; and that the earliest premigratory neural crest are biased towards either a neuronal or ectomesenchymal fate, with each lineage expressing distinct factors from the pluripotent state. We profile the spatiotemporal emergence of each neural crest population and demonstrate that the ectomesenchymal lineage forms prior to the neuronal progenitors. Expression of the pluripotency microRNA family miR-302 is maintained in cranial neural crest cells and genetic deletion leads to precocious specification of the ectomesenchymal lineage. We find that miR-302 directly targets Sox9 to slow the timing of ectomesenchyme induction and regulates multiple genes involved in chromatin condensation to maintain accessibility for neuronal differentiation. Loss of mir-302 results in reduced chromatin accessibility in the neuronal progenitor lineage of neural crest and a reduction in peripheral neuron differentiation. Our findings reveal a post-transcriptional mechanism governed by miRNAs from pluripotency as an important mechanism to expand developmental potential of cranial neural crest.
Project description:Neural cest cells are a transient stem cell-like population appearing during vertebrate embryonic development. Generation of the cranial neural crest is known to require a balanced combination of FGF and BMP levels. However, it is poorly understood how the functions of such growth factors are controlled in the extracellular spaces. Here we identifiy the extracelluar matrix protein anosmin (Gga.14976.1.S1_at, clone ChEST132d10) as a novel molecule synthesized locally in the cranial neural crest of chicken embryos. Cranial neural folds (NF) and ventral neural plates (NP) were dissected from Hamburger & Hamilton stage 8 (HH8) embryos (80 to 14 embryos, n=4), and total RNA was analyzed using a GeneChip chicken genome arrays (Affymetrix)
Project description:We employ RNA-seq of FACS sorted cell populations to identify genes that are enriched in cranial neural crest in relationship to the trunk. Transcriptional profiling of delaminating cranial and trunk neural crest subpopulations.
Project description:Neural cest cells are a transient stem cell-like population appearing during vertebrate embryonic development. Generation of the cranial neural crest is known to require a balanced combination of FGF and BMP levels. However, it is poorly understood how the functions of such growth factors are controlled in the extracellular spaces. Anosmin is an extracellular matrix protein implicated in FGF signaling and mutated in Kallmann syndrome. Here, we demonstrate that anosmin (Gga.14976.1.S1_at, clone ChEST132d10) is synthesized locally in the cranial neural crest of chicken embryos and is essential for cranial neural crest formation. Anosmin upregulates FGF8 and BMP5 gene expression; it also enhances FGF8 activity while inhibiting BMP5 and WNT3a signaling. Taken together, our data establish that the matrix protein anosmin is required for cranial neural crest formation, with funtional modulation of FGF, BMP, and WNT.
Project description:TWIST1, a basic helix-loop-helix transcription factor is essential for the development of cranial mesoderm and cranial neural crest-derived craniofacial structures. Our previous work showed that, in the absence of TWIST1, some cells within the cranial mesoderm adopt an abnormal epithelial configuration. Here, we show by transcriptome analysis that loss of TWIST1 in the cranial mesoderm is accompanied by a reduction in the expression of genes that are associated with cell-extracellular matrix interactions and the acquisition of mesenchymal characteristics. By comparing the transcriptional profiles of cranial mesoderm-specific Twist1 loss-of-function mutant and control mouse embryos, we identified a set of genes that are both TWIST1-dependent and predominantly expressed in the mesoderm. By ChIP-seq in a cell line model of a TWIST1-dependent mesenchymal state, we identified, among the downstream genes, three direct transcriptional targets of TWIST1: Ddr2, Pcolce and Tgfbi. Our findings show that the mesenchymal properties of the cranial mesoderm is likely to be regulated by a network of TWIST1 targets genes that influence the extracellular matrix and cell-matrix interactions, and collectively they are required for the morphogenesis of the craniofacial structures. Cranial neural crest and cranial mesoderm cells were isolated by flow sorting of GFP reporter-labelled cells collected from heads of E9.5 mouse embryos. Three replicates were independently isolated and hybridized to Illumina mouse WG v 2.0 chips