Project description:Neural tube closure in vertebrates is achieved through a highly dynamic and coordinated series of morphogenic events involving neural plate, surface ectoderm, and neural plate border. Failure of this process in the caudal region causes spina bifida. Grainyhead-like 3 (GRHL3) is an indispensable transcription factor for neural tube closure as constitutive inactivation of which leads to fully penetrant spina bifida. Here, through single-cell transcriptomics we show that at E8.5, the time-point preceding mouse neural tube closure, the co-expression of Grhl3, Tfap2a, and Tfap2c defines a previously unrecognised progenitor population of surface ectoderm. Specific deletion of Grhl3 expression using Tfap2a-Cre recapitulate the spina bifida observed in Grhl3-null animals. Moreover, conditional inactivation of Tfap2c expression in Grhl3-expressing neural plate border cells also causes mild spina bifida. These findings clearly indicate that Grhl3-expressing neural plate border cells cohort is required for the early-stage neurulation.
Project description:During primary neurulation, the separation of a single-layered ectodermal sheet into the surface ectoderm (SE) and neural tube specifies SE and neural ectoderm (NE) cell fates. The mechanisms underlying fate specification in conjunction with neural tube closure are poorly understood. Here, by comparing expression profiles between SE and NE lineages, we observed that uncommitted progenitor cells, expressing stem cell markers, are present in the neural plate border/neural fold prior to neural tube closure. To identify what type of signaling pathways and transcriptional factors are involved in the fate specification between SE and NE cells during neurulation.
Project description:During primary neurulation, the separation of a single-layered ectodermal sheet into the surface ectoderm (SE) and neural tube specifies SE and neural ectoderm (NE) cell fates. The mechanisms underlying fate specification in conjunction with neural tube closure are poorly understood. Here, by comparing expression profiles between SE and NE lineages, we observed that uncommitted progenitor cells, expressing stem cell markers, are present in the neural plate border/neural fold prior to neural tube closure.
Project description:Purpose: Identify genes and pathways affected in tuft embryos with NTDs Results: Expression of genes associated with neural tube closure and components of non-canonical WNT signaling/PCP pathways were affected Conclusions: TET1 regulates genes associated with neural tube closure
Project description:Grainyhead-like transcription factor 3 (GRHL3) directs surface ectoderm differentiation under the control of the canonical Wnt/β-catenin pathway. However, the molecular mechanisms that control nuclear GRHL3 expression through β-catenin are not fully understood. Here, we show that the essential for mitotic growth 1 (EMG1) protein constitutes a protein complex with GRHL3, and that EMG1 is required for correct nuclear localization of GRHL3, and for activation of the canonical Wnt signaling pathway. Conditional knockout mutation of Emg1 in the GRHL3-positive surface ectoderm causes neural tube defects at the level of the spinal cord, i.e. spina bifida. Additionally, the severity of compound mutant phenotypes of the Emg1 and Grhl3 genes indicates that they interact genetically in neurulation and palate development. These lines of evidence demonstrate that EMG1 cooperates with GRHL3 in β-catenin–mediated surface ectoderm differentiation. Since the EMG1 mutation causes Bowen-Conradi syndrome and the GRHL3 mutation causes Van der Woude syndrome 2, both of which are associated with neural tube dysplasia and cleft palate, our study will help to better understand the pathogenic mechanisms of these two human genetic diseases.
Project description:Grainyhead-like transcription factor 3 (GRHL3) directs surface ectoderm differentiation under the control of the canonical Wnt/β-catenin pathway. However, the molecular mechanisms that control nuclear GRHL3 expression through β-catenin are not fully understood. Here, we show that the essential for mitotic growth 1 (EMG1) protein constitutes a protein complex with GRHL3, and that EMG1 is required for correct nuclear localization of GRHL3, and for activation of the canonical Wnt signaling pathway. Conditional knockout mutation of Emg1 in the GRHL3-positive surface ectoderm causes neural tube defects at the level of the spinal cord, i.e. spina bifida. Additionally, the severity of compound mutant phenotypes of the Emg1 and Grhl3 genes indicates that they interact genetically in neurulation and palate development. These lines of evidence demonstrate that EMG1 cooperates with GRHL3 in β-catenin–mediated surface ectoderm differentiation. Since the EMG1 mutation causes Bowen-Conradi syndrome and the GRHL3 mutation causes Van der Woude syndrome 2, both of which are associated with neural tube dysplasia and cleft palate, our study will help to better understand the pathogenic mechanisms of these two human genetic diseases.
Project description:Cell intrinsic factors that control neuroectoderm specification of early embryonic cells include the nucleoprotein Geminin (Gmnn) and the Zic family of zinc finger transcription factors. Gmnn modulates chromatin state to activate neural gene expression during neural cell fate acquisition, while Gmnn deficiency in the forming neural plate disrupts transcriptional programs that control neural cell specification, neural plate patterning and neurogenesis, resulting in neural tube defects. Likewise, Zic1 over-expression promotes neural gene expression, while heterozygous deletion of Zic1/4 leads to Dandy-Walker malformation, the most common congenital cerebellar malformation. During embryonic development, Geminin and Zic1 expression is enriched in neuroectoderm from gastrula stages, with broad expression in the forming CNS during post-gastrula stages, when neural tube closure and neurogenesis are initiated. To gain a greater understanding of the molecular events that regulate neural cell specification, here we used ChIP-seq to define genome-wide chromatin binding profiles for Gmnn in embryonic stem cells (ESCs) and for Gmnn and Zic1 during specification of ESCs into neuroectoderm.
Project description:Maternal diabetes is a teratogen that can lead to neural tube closure defects in the offspring. In neurulation-stage embryos from diabetic dams, we detected abnormal tissue protruding from the open neural tube. To determine the origin of such protrusions, we compared gene expression profiles between open neural plate with normal morphology, and protrusion tissue. Neurulation-stage mouse embryos at 8.5 days of gestation were used to prepare open neural tube at the anterior aspect of neural tube closure site 1 by laser capture microdissection. For each sample, 10 sections were pooled, total RNA was extracted, and 7 ng of total RNA were used for expression profiling by Tag sequencing using an Applied Biosystems SolidSAGE kit for library construction, and an AB SOLiD 5500 XL instrument for sequencing. Protrusion tissue was prepared from whole embryos by microdissection, and 12ng of total RNA per sample was used for Tag sequencing. Sequence reads were mapped to RefSeq RNA, and count data per gene were obtained using a modified version of the Applied Biosystems SOLiD⢠SAGE⢠Analysis Software. Neural plate protrusion compared to open neural plate anterior of closure site 1 with normal morphology
Project description:The formation of the mammalian brain requires regionalization and morphogenesis of the cranial neural plate, which transforms from an epithelial sheet into a closed tube that provides the structural foundation for neural patterning and circuit formation. Sonic hedgehog (SHH) signaling is important for cranial neural plate patterning and closure, but the transcriptional changes that give rise to the spatially regulated cell fates and behaviors that build the cranial neural tube have not been systematically analyzed. Here we used single-cell RNA sequencing to generate an atlas of gene expression at six consecutive stages of cranial neural tube closure in the mouse embryo. Ordering transcriptional profiles relative to the major axes of gene expression predicted spatially regulated expression of 870 genes along the anterior-posterior and mediolateral axes of the cranial neural plate and reproduced known expression patterns with over 85% accuracy. Single-cell RNA sequencing of embryos with activated SHH signaling revealed distinct SHH-regulated transcriptional programs in the developing forebrain, midbrain, and hindbrain, suggesting a complex interplay between anterior-posterior and mediolateral patterning systems. These results define a spatiotemporally resolved map of gene expression during cranial neural tube closure and provide a resource for investigating the transcriptional events that drive early mammalian brain development.
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 (NBSCs). Moreover, human (i)NBSCs share molecular and functional features with primary Neural Plate Border Stem Cells (pNBSCs) isolated from neural folds of E8.5 mouse embryos. Here we provide single cell RNA-sequencing data of neural tissue derived from two E8.5 mouse embryos. After manual isolation and enzymatic separation E8.5 neural tissue was single cell sorted and RNA sequencing was performed following the Smart-seq2 protocol. In sum, cultured pNBSCs and E8.5 neural tube cells share a similar regional identity and expression signature suggesting that pNBSCs might correspond to an endogenous progenitor in this area of the developing brain.