Dataset Information

Dissecting early regulatory relationships in the lamprey neural crest gene network.

ABSTRACT: The neural crest, a multipotent embryonic cell type, originates at the border between neural and nonneural ectoderm. After neural tube closure, these cells undergo an epithelial-mesenchymal transition, migrate to precise, often distant locations, and differentiate into diverse derivatives. Analyses of expression and function of signaling and transcription factors in higher vertebrates has led to the proposal that a neural crest gene regulatory network (NC-GRN) orchestrates neural crest formation. Here, we interrogate the NC-GRN in the lamprey, taking advantage of its slow development and basal phylogenetic position to resolve early inductive events, 1 regulatory step at the time. To establish regulatory relationships at the neural plate border, we assess relative expression of 6 neural crest network genes and effects of individually perturbing each on the remaining 5. The results refine an upstream portion of the NC-GRN and reveal unexpected order and linkages therein; e.g., lamprey AP-2 appears to function early as a neural plate border rather than a neural crest specifier and in a pathway linked to MsxA but independent of ZicA. These findings provide an ancestral framework for performing comparative tests in higher vertebrates in which network linkages may be more difficult to resolve because of their rapid development.

SUBMITTER: Nikitina N

PROVIDER: S-EPMC2629288 | biostudies-other | 2008 Dec

REPOSITORIES: biostudies-other

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Dissecting early regulatory relationships in the lamprey neural crest gene network.

Nikitina Natalya N Sauka-Spengler Tatjana T Bronner-Fraser Marianne M

Proceedings of the National Academy of Sciences of the United States of America 20081222 51

The neural crest, a multipotent embryonic cell type, originates at the border between neural and nonneural ectoderm. After neural tube closure, these cells undergo an epithelial-mesenchymal transition, migrate to precise, often distant locations, and differentiate into diverse derivatives. Analyses of expression and function of signaling and transcription factors in higher vertebrates has led to the proposal that a neural crest gene regulatory network (NC-GRN) orchestrates neural crest formation ...[more]

PMID: 19104059

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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: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. Transcriptomes of animal caps overexpressing Pax3+/-Zic1 in the presence/absence of cycloheximide, a translation inhibitor, were compared to control animal caps to identify direct Pax3 and Zic1 targets 2-4 cells stage embryos were injected with inducible Pax3-GR+/-Zic1-GR constructs. Animal caps were cut at stage 9. Cycloheximide (Chx, 0.1mg/ml) was then applied to the healed animal caps, from stage 10 to 10.5 (i.e. for 30 min at 23*C), then dexamethasone (Dex) was added at stage 10.5 to the cycloheximide-containing medium. Explants were rinced and lysed after two additional hours at 23*C, i.e. when sibling embryos reached stage 11.5-12. Total RNA was then extracted and hybridized on Affymetrix microarrays. Transcriptomes were compared to determine Pax3 and Zic1 targets.

Dataset Information

Dissecting early regulatory relationships in the lamprey neural crest gene network.

Publications

Dissecting early regulatory relationships in the lamprey neural crest gene network.

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