"Beyond transcription: How post-transcriptional mechanisms drive neural crest EMT".

The neural crest is a stem cell population that originates from the ectoderm during the initial steps of nervous system development. Neural crest cells delaminate from the neuroepithelium by undergoing a spatiotemporally regulated epithelial-mesenchymal transition (EMT) that proceeds in a coordinated wave head-to-tail to exit from the neural tube. While much is known about the transcriptional programs and membrane changes that promote EMT, there are additional levels of gene expression control that neural crest cells exert at the level of RNA to control EMT and migration. Yet, the role of post-transcriptional regulation, and how it drives and contributes to neural crest EMT, is not well understood. In this mini-review, we explore recent advances in our understanding of the role of post-transcriptional regulation during neural crest EMT.

Developmentally programmed histone H3 expression regulates cellular plasticity at the parental-to-early embryo transition.

During metazoan development, the marked change in developmental potential from the parental germline to the embryo raises an important question regarding how the next life cycle is reset. As the basic unit of chromatin, histones are essential for regulating chromatin structure and function and, accordingly, transcription. However, the genome-wide dynamics of the canonical, replication-coupled (RC) histones during gametogenesis and embryogenesis remain unknown. In this study, we use CRISPR-Cas9-mediated gene editing in Caenorhabditis elegans to investigate the expression pattern and role of individual RC histone H3 genes and compare them to the histone variant, H3.3. We report a tightly regulated epigenome landscape change from the germline to embryos that are regulated through differential expression of distinct histone gene clusters. Together, this study reveals that a change from a H3.3- to H3-enriched epigenome during embryogenesis restricts developmental plasticity and uncovers distinct roles for individual H3 genes in regulating germline chromatin.