Developmental regulatory networks controlling neural crest multipotency and differentiation

Abstract

Neural crest cells are a migratory and multipotent stem cell population that are specified at the dorsal aspect of the neural tube in developing vertebrate embryos. The neural crest has been studied for centuries and was first identified for their ability to migrate broadly throughout the embryo. Classical lineage tracing studies, now affirmed by genetic fate mapping, have confirmed that multipotent neural crest progenitors can contribute to a diverse array of fates including sensory neurons and glia in the peripheral nervous system, the dermis and craniofacial skeleton, melanocytes, Schwann cells, the enteric nervous system, cardiac septum, the outflow tract of the heart, and more. To better understand how neural crest cells achieve such varied developmental potential, extensive work has been performed to create hierarchical and temporal gene regulatory networks (GRNs) that both identify distinct cell states and their functional output. One limitation of the current state of the neural crest GRN is that it is generated from a compilation of experimental evidence in mice, chick, frog, and zebrafish, leading to inconsistencies due to functional divergence or gene duplication events. Furthermore, despite advances in genomic profiling, network-level reconstructions of the neural crest GRN are unable to resolve the precise timing and complexity of multiple circuits using a single assay. My thesis research focuses on the cranial subpopulation of neural crest, which is unique in its ability to give rise to ectomesenchyme – or mesenchymal cells derived from the ectoderm. In this work, I characterize the role of the canonical pluripotent transcription factors OCT4 and SOX2 and their co-opted role to promote neural crest multipotency. Additionally, I examined developing neural crest cells using single cell ATAC-Seq to identify the transcription factors and developmental gene regulatory circuits driving differentiation in neural crest. This work unveiled the regulatory circuits behind seven different lineages within the earliest stages of cranial neural crest development. Understanding these regulatory networks provide valuable insight into the control of stem cell multipotency and may be used to guide directed differentiation of neural crest derivatives in future studies.