From Neural Crest to Definitive Roof Plate: The Dynamic Behavior of the Dorsal Neural Tube

Research on the development of the dorsal neural tube is particularly challenging. In this highly dynamic domain, a temporal transition occurs between early neural crest progenitors that undergo an epithelial-to-mesenchymal transition and exit the neural primordium, and the subsequent roof plate, a resident epithelial group of cells that constitutes the dorsal midline of the central nervous system. Among other functions, the roof plate behaves as an organizing center for the generation of dorsal interneurons. Despite extensive knowledge of the formation, emigration and migration of neural crest progenitors, little is known about the mechanisms leading to the end of neural crest production and the transition into a roof plate stage. Are these two mutually dependent or autonomously regulated processes? Is the generation of roof plate and dorsal interneurons induced by neural tube-derived factors throughout both crest and roof plate stages, respectively, or are there differences in signaling properties and responsiveness as a function of time? In this review, we discuss distinctive characteristics of each population and possible mechanisms leading to the shift between the above cell types.

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Cadherin-11 is required for neural crest determination and survival

10.1101/2020.05.18.066613 ◽

2020 ◽

Cited By ~ 1

Author(s):

Subrajaa Manohar ◽

Alberto Camacho ◽

Crystal D. Rogers

Keyword(s):

Cell Migration ◽

Neural Crest ◽

Neural Tube ◽

Epithelial To Mesenchymal Transition ◽

Congenital Defects ◽

Embryonic Cells ◽

Developmental Defects ◽

Mesenchymal Transition ◽

Dorsal Neural Tube ◽

And Migration

AbstractNeural crest (NC) cells are multipotent embryonic cells that form melanocytes, craniofacial bone and cartilage, and the peripheral nervous system in vertebrates. NC cells express many cadherin proteins, which control their specification, epithelial to mesenchymal transition (EMT), migration, and mesenchymal to epithelial transition. Abnormal NC development leads to congenital defects including craniofacial clefts as well as NC-derived cancers. Here, we identify the role of the type II cadherin protein, Cadherin-11 (CDH11), in early chicken NC development. CDH11 is crucial for NC cell migration in amphibian embryos and is linked to cell survival, proliferation, and migration in cancer cells. It has been linked to the complex neurocristopathy disorder, Elsahy‐Waters Syndrome, in humans. Using immunohistochemistry (IHC), we determined that CDH11 protein has dynamic expression that is first co-localized with neural progenitors in early embryos and subsequently upregulated specifically in NC cells as they are specified in the dorsal neural tube prior to migration. We identified that loss of CDH11 led to a reduction of bonafide NC cells in the dorsal neural tube combined with defects in cell migration and survival. Loss of CDH11 increased p53-mediated programmed-cell death, and blocking the p53 pathway rescued the NC phenotype. Our findings demonstrate an early requirement for CDH11 in NC development, and may increase our understanding of early cadherin-related NC developmental defects.SummaryChicken Cadherin-11 (CDH11), which is expressed in neural crest (NC) cells prior to NC cell migration, is necessary for the determination and survival of the premigratory NC population.

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Notch signaling is a critical initiator of roof plate formation as revealed by the use of RNA profiling of the dorsal neural tube

BMC Biology ◽

10.1186/s12915-021-01014-3 ◽

2021 ◽

Vol 19 (1) ◽

Cited By ~ 1

Author(s):

Shai Ofek ◽

Sophie Wiszniak ◽

Sarah Kagan ◽

Markus Tondl ◽

Quenten Schwarz ◽

...

Keyword(s):

Nervous System ◽

Notch Signaling ◽

Neural Tube ◽

Cell Types ◽

Molecular Heterogeneity ◽

Specific Cell ◽

Rna Profiling ◽

Dorsal Neural Tube ◽

Roof Plate ◽

The Central Nervous System

AbstractBackgroundThe dorsal domain of the neural tube is an excellent model to investigate the generation of complexity during embryonic development. It is a highly dynamic and multifaceted region being first transiently populated by prospective neural crest (NC) cells that sequentially emigrate to generate most of the peripheral nervous system. Subsequently, it becomes the definitive roof plate (RP) of the central nervous system. The RP, in turn, constitutes a patterning center for dorsal interneuron development. The factors underlying establishment of the definitive RP and its segregation from NC and dorsal interneurons are currently unknown.ResultsWe performed a transcriptome analysis at trunk levels of quail embryos comparing the dorsal neural tube at premigratory NC and RP stages. This unraveled molecular heterogeneity between NC and RP stages, and within the RP itself. By implementing these genes, we asked whether Notch signaling is involved in RP development. First, we observed that Notch is active at the RP-interneuron interface. Furthermore, gain and loss of Notch function in quail and mouse embryos, respectively, revealed no effect on early NC behavior. Constitutive Notch activation caused a local downregulation of RP markers with a concomitant development of dI1 interneurons, as well as an ectopic upregulation of RP markers in the interneuron domain. Reciprocally, in mice lacking Notch activity, both the RP and dI1 interneurons failed to form and this was associated with expansion of the dI2 population.ConclusionsCollectively, our results offer a new resource for defining specific cell types, and provide evidence that Notch is required to establish the definitive RP, and to determine the choice between RP and interneuron fates, but not the segregation of RP from NC.

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Cadherin-6B proteolysis promotes the neural crest cell epithelial-to-mesenchymal transition through transcriptional regulation

The Journal of Cell Biology ◽

10.1083/jcb.201604006 ◽

2016 ◽

Vol 215 (5) ◽

pp. 735-747 ◽

Cited By ~ 21

Author(s):

Andrew T. Schiffmacher ◽

Vivien Xie ◽

Lisa A. Taneyhill

Keyword(s):

Neural Crest ◽

Epithelial To Mesenchymal Transition ◽

Neural Crest Cell ◽

Cranial Neural Crest ◽

Mesenchymal Transition ◽

Effector Genes ◽

A Disintegrin And Metalloproteinase ◽

And Migration ◽

Cranial Neural Crest Cells

During epithelial-to-mesenchymal transitions (EMTs), cells disassemble cadherin-based junctions to segregate from the epithelia. Chick premigratory cranial neural crest cells reduce Cadherin-6B (Cad6B) levels through several mechanisms, including proteolysis, to permit their EMT and migration. Serial processing of Cad6B by a disintegrin and metalloproteinase (ADAM) proteins and γ-secretase generates intracellular C-terminal fragments (CTF2s) that could acquire additional functions. Here we report that Cad6B CTF2 possesses a novel pro-EMT role by up-regulating EMT effector genes in vivo. After proteolysis, CTF2 remains associated with β-catenin, which stabilizes and redistributes both proteins to the cytosol and nucleus, leading to up-regulation of β-catenin, CyclinD1, Snail2, and Snail2 promoter-based GFP expression in vivo. A CTF2 β-catenin–binding mutant, however, fails to alter gene expression, indicating that CTF2 modulates β-catenin–responsive EMT effector genes. Notably, CTF2 association with the endogenous Snail2 promoter in the neural crest is β-catenin dependent. Collectively, our data reveal how Cad6B proteolysis orchestrates multiple pro-EMT regulatory inputs, including CTF2-mediated up-regulation of the Cad6B repressor Snail2, to ensure proper cranial neural crest EMT.

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Draxin acts as a molecular rheostat of canonical Wnt signaling to control cranial neural crest EMT

The Journal of Cell Biology ◽

10.1083/jcb.201709149 ◽

2018 ◽

Vol 217 (10) ◽

pp. 3683-3697 ◽

Cited By ~ 21

Author(s):

Erica J. Hutchins ◽

Marianne E. Bronner

Keyword(s):

Wnt Signaling ◽

Neural Crest ◽

Neural Tube ◽

Epithelial To Mesenchymal Transition ◽

Cranial Neural Crest ◽

Canonical Wnt Signaling ◽

Mesenchymal Transition ◽

Molecular Rheostat ◽

Timing Of Initiation ◽

Canonical Wnt

Neural crest cells undergo a spatiotemporally regulated epithelial-to-mesenchymal transition (EMT) that proceeds head to tailward to exit from the neural tube. In this study, we show that the secreted molecule Draxin is expressed in a transient rostrocaudal wave that mirrors this emigration pattern, initiating after neural crest specification and being down-regulated just before delamination. Functional experiments reveal that Draxin regulates the timing of cranial neural crest EMT by transiently inhibiting canonical Wnt signaling. Ectopic maintenance of Draxin in the cranial neural tube blocks full EMT; while cells delaminate, they fail to become mesenchymal and migratory. Loss of Draxin results in premature delamination but also in failure to mesenchymalize. These results suggest that a pulse of intermediate Wnt signaling triggers EMT and is necessary for its completion. Taken together, these data show that transient secreted Draxin mediates proper levels of canonical Wnt signaling required to regulate the precise timing of initiation and completion of cranial neural crest EMT.

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Mechanisms of Neural Crest Migration

Annual Review of Genetics ◽

10.1146/annurev-genet-120417-031559 ◽

2018 ◽

Vol 52 (1) ◽

pp. 43-63 ◽

Cited By ~ 46

Author(s):

András Szabó ◽

Roberto Mayor

Keyword(s):

Neural Crest ◽

Cell Population ◽

Epithelial To Mesenchymal Transition ◽

Neural Crest Cells ◽

Cell Types ◽

Embryonic Cell ◽

Mesenchymal Transition ◽

Chain Migration ◽

Mass Migration ◽

Neural Crest Migration

Neural crest cells are a transient embryonic cell population that migrate collectively to various locations throughout the embryo to contribute a number of cell types to several organs. After induction, the neural crest delaminates and undergoes an epithelial-to-mesenchymal transition before migrating through intricate yet characteristic paths. The neural crest exhibits a variety of migratory behaviors ranging from sheet-like mass migration in the cephalic regions to chain migration in the trunk. During their journey, neural crest cells rely on a range of signals both from their environment and within the migrating population for navigating through the embryo as a collective. Here we review these interactions and mechanisms, including chemotactic cues of neural crest cells’ migration.

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Sip1 mediates an E-cadherin-to-N-cadherin switch during cranial neural crest EMT

The Journal of Cell Biology ◽

10.1083/jcb.201305050 ◽

2013 ◽

Vol 203 (5) ◽

pp. 835-847 ◽

Cited By ~ 91

Author(s):

Crystal D. Rogers ◽

Ankur Saxena ◽

Marianne E. Bronner

Keyword(s):

Neural Crest ◽

Neural Tube ◽

Molecular Mechanisms ◽

Epithelial To Mesenchymal Transition ◽

Critical Role ◽

Embryonic Stem ◽

Neural Crest Cell ◽

Stem Cell Population ◽

Mesenchymal Transition ◽

E Cadherin

The neural crest, an embryonic stem cell population, initially resides within the dorsal neural tube but subsequently undergoes an epithelial-to-mesenchymal transition (EMT) to commence migration. Although neural crest and cancer EMTs are morphologically similar, little is known regarding conservation of their underlying molecular mechanisms. We report that Sip1, which is involved in cancer EMT, plays a critical role in promoting the neural crest cell transition to a mesenchymal state. Sip1 transcripts are expressed in premigratory/migrating crest cells. After Sip1 loss, the neural crest specifier gene FoxD3 was abnormally retained in the dorsal neuroepithelium, whereas Sox10, which is normally required for emigration, was diminished. Subsequently, clumps of adherent neural crest cells remained adjacent to the neural tube and aberrantly expressed E-cadherin while lacking N-cadherin. These findings demonstrate two distinct phases of neural crest EMT, detachment and mesenchymalization, with the latter involving a novel requirement for Sip1 in regulation of cadherin expression during completion of neural crest EMT.

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Notch signaling is a critical initiator of roof plate formation as revealed by the use of RNA profiling of the dorsal neural tube

10.1101/2020.12.09.417279 ◽

2020 ◽

Author(s):

Shai Ofek ◽

Sophie Wiszniak ◽

Sarah Kagan ◽

Markus Tondl ◽

Quenten Schwarz ◽

...

Keyword(s):

Notch Signaling ◽

Neural Tube ◽

Transcriptome Analysis ◽

Cell Types ◽

Molecular Heterogeneity ◽

Specific Cell ◽

Rna Profiling ◽

Dorsal Neural Tube ◽

Roof Plate ◽

Plate Formation

AbstractThe factors underlying establishment of the definitive roof plate (RP) and its segregation from neural crest (NC) and interneurons are unknown. We performed transcriptome analysis at trunk levels of quail embryos comparing the dorsal neural tube at premigratory NC and RP stages. This unraveled molecular heterogeneity between NC and RP stages, and within the RP itself. By implementing these genes, we asked whether Notch signaling is involved in RP development. First, we observed that Notch is active at the RP-interneuron interface. Furthermore, gain and loss of Notch function in quail and mouse embryos, respectively, revealed no effect on early NC behavior. Constitutive Notch activation caused a local downregulation of RP markers with a concomitant development of dI1 interneurons, as well as an ectopic upregulation of RP markers in the interneuron domain. Reciprocally, in mice lacking Notch activity both the RP and dI1 interneurons failed to form and this was associated with expansion of the dI2 population. Collectively, our results offer a new resource for defining specific cell types, and provide evidence that Notch is required to establish the definitive RP, and to determine the choice between RP and interneuron fates, but not the segregation of RP from NC.Summary statementA new set of genes involved in Notch-dependent roof plate formation is unraveled by transcriptome analysis.

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A somatic piRNA pathway regulates epithelial-to-mesenchymal transition of chick neural crest cells

10.1101/2021.04.30.442165 ◽

2021 ◽

Author(s):

Riley Galton ◽

Katalin Fejes-Toth ◽

Marianne E. Bronner

Keyword(s):

Neural Crest ◽

Neural Tube ◽

Epithelial To Mesenchymal Transition ◽

Embryonic Stem ◽

Neural Crest Cells ◽

Stem Cell Population ◽

Small Rna Sequencing ◽

Mesenchymal Transition ◽

Sox2 Expression ◽

Pirna Pathway

AbstractIn the metazoan germline, Piwi proteins play an essential regulatory role in maintenance of stemness and self-renewal by piRNA-mediated repression of transposable elements. To date, the activity of Piwi proteins and the piRNA pathway in vertebrates was believed to be confined to the gonads. Our results reveal expression of Piwil1 in a vertebrate somatic cell type, the neural crest–a migratory embryonic stem cell population. We show that Piwil1 is expressed at low levels throughout chick neural crest development, peaking just before neural crest cells undergo an epithelial-to-mesenchymal transition to leave the neural tube and migrate into the periphery. Importantly, loss of Piwil1 impedes neural crest emigration. Small RNA sequencing reveals somatic piRNAs with sequence signatures of an active ping pong loop. Coupled with Piwil1 knockout RNA-seq, our data suggest that Piwil1 regulates expression of the transposon derived gene ERNI in the chick dorsal neural tube, which in turn suppresses Sox2 expression to precisely control the timing of neural crest specification and emigration. Our work provides mechanistic insight into a novel function of the piRNA pathway as a regulator of somatic development in vertebrates.

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