Identification and Characterization of Intermediate Cellular States During Mammalian Neural Crest Cell Epithelial-to-Mesenchymal Transition and Delamination

Core Concepts

Mammalian neural crest cells undergo epithelial-to-mesenchymal transition (EMT) and delamination through distinct intermediate cellular states that are characterized by specific transcriptional signatures and cell cycle phases.

Abstract

The content describes a study that used single-cell RNA sequencing to identify and characterize intermediate cellular states during the epithelial-to-mesenchymal transition (EMT) and delamination of mouse cranial neural crest cells (NCC). The key findings are: Two distinct intermediate NCC populations were identified, one in S phase and one in G2/M phase of the cell cycle, suggesting NCC can undergo EMT and delamination in different cell cycle stages. Trajectory analysis showed these intermediate NCC populations form simultaneously and independently, but later converge into a common pool of early migratory NCC. The intermediate NCC populations exhibited distinct transcriptional signatures, including downregulation of epithelial genes and upregulation of genes involved in cell protrusion and cytoskeletal rearrangement. Spatial mapping using SABER-FISH localized the intermediate NCC populations to the dorsolateral region of the neural plate. Knockdown of the intermediate NCC marker Dlc1 reduced the number of migratory NCC, revealing its critical role in regulating NCC delamination. Overall, the study provides novel insights into the cellular and molecular mechanisms governing the EMT and delamination of mammalian neural crest cells during development.

Stats

Approximately 80% of delaminating cranial NCC express either EdU (S phase marker) or pHH3 (G2/M phase marker). In contrast, nearly 50% of premigratory, non-delaminating trunk NCC do not express either cell cycle marker. Dlc1 knockdown resulted in a significant 30% reduction in the number of migratory NCC compared to control.

Quotes

"Our results illustrate the progressive transcriptional and spatial transitions from premigratory to migratory cranial NCC during EMT and delamination." "Gene expression and trajectory analysis indicate that distinct intermediate populations of NCC delaminate in either S phase or G2/M phase of the cell cycle." "Transcriptional knockdown revealed a functional role for the intermediate stage marker Dlc1 in regulating NCC delamination and migration."

Key Insights Distilled From

Identification and characterization of intermediate states in mammalian neural crest cell epithelial to mesenchymal transition and delamination

by Zhao,R., Moo... at www.biorxiv.org 10-26-2023

https://www.biorxiv.org/content/10.1101/2023.10.26.564204v2

Deeper Inquiries

How do the signaling pathways and regulatory networks governing EMT and delamination differ between cranial and trunk neural crest cells?

In the context of neural crest cell (NCC) development, the signaling pathways and regulatory networks governing epithelial to mesenchymal transition (EMT) and delamination can differ between cranial and trunk NCC. Cranial NCCs and trunk NCCs exhibit distinct behaviors during development, including differences in the timing and manner of delamination. Cranial NCCs typically delaminate from the neuroepithelium at the dorsolateral neural plate border before neural tube closure, while trunk NCCs delaminate after neural tube closure. This difference in timing suggests that the signaling pathways and regulatory networks controlling EMT and delamination may be distinct between the two populations. For example, cranial NCC delamination is associated with the breakdown of tight junctions and apicobasal polarity, which are hallmarks of EMT. In contrast, trunk NCC delamination may involve different molecular mechanisms to facilitate their migration and differentiation. Furthermore, cranial and trunk NCCs give rise to different derivatives in the body, such as craniofacial bones and cartilages for cranial NCCs, and sympathetic ganglia and melanocytes for trunk NCCs. These different fates suggest that the signaling pathways and regulatory networks governing EMT and delamination in cranial and trunk NCCs are tailored to meet the specific developmental requirements of each population.

What are the potential implications of the identified intermediate NCC populations and their distinct cell cycle states for understanding neural crest-derived diseases or neurocristopathies?

The identification of intermediate NCC populations with distinct cell cycle states during EMT and delamination has significant implications for understanding neural crest-derived diseases or neurocristopathies. Neurocristopathies are developmental disorders that arise from abnormalities in neural crest cell development, migration, or differentiation. By studying the intermediate NCC populations and their cell cycle states, researchers can gain insights into the molecular mechanisms underlying neurocristopathies and potentially identify new therapeutic targets. For example, if disruptions in the cell cycle progression of NCCs during EMT and delamination contribute to the pathogenesis of neurocristopathies, targeting specific cell cycle regulators or signaling pathways could be a potential strategy for treating these disorders. Additionally, understanding how intermediate NCC populations transition between different cell cycle phases could provide valuable information on the timing and coordination of events during neural crest development, which may be dysregulated in neurocristopathies. Overall, the characterization of intermediate NCC populations and their cell cycle states not only enhances our understanding of normal neural crest development but also provides a foundation for investigating the molecular basis of neural crest-derived diseases and developing targeted therapies.

Could the mechanisms regulating NCC EMT and delamination provide insights into the epithelial-mesenchymal plasticity observed in cancer metastasis?

The mechanisms regulating NCC EMT and delamination could indeed provide valuable insights into the epithelial-mesenchymal plasticity (EMP) observed in cancer metastasis. EMP is a phenomenon where cancer cells exhibit intermediate states between epithelial and mesenchymal phenotypes, allowing them to acquire migratory and invasive properties. By studying the intermediate NCC populations during EMT and delamination, researchers can uncover common molecular pathways and regulatory networks that govern cellular plasticity in both developmental processes and cancer progression. For instance, the identification of distinct intermediate NCC populations transitioning between epithelial and mesenchymal states, characterized by changes in gene expression and cell cycle status, mirrors the EMP observed in cancer cells. Understanding how these intermediate states are regulated in NCCs could shed light on similar processes in cancer cells and provide new targets for therapeutic intervention. Additionally, the role of specific genes, such as Dlc1, in regulating NCC EMT and delamination may have implications for cancer metastasis. Dlc1 is known to be involved in cell migration and cytoskeletal dynamics, which are critical processes in cancer cell invasion and metastasis. Therefore, insights gained from studying NCC development could be translated to understanding the mechanisms of EMP in cancer and potentially lead to the development of novel anti-metastatic therapies. In conclusion, the parallels between NCC EMT and delamination and EMP in cancer metastasis highlight the potential for cross-disciplinary research to uncover fundamental principles of cellular plasticity and identify new strategies for combating metastatic disease.