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 chroma-tin, 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 Caenorhab-ditis 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.

Automated summary

During metazoan development, there is a marked change in developmental potential from the parental germline to the embryo, and this study aims to understand how the next life cycle is reset. Through gene editing techniques, the study investigates the expression pattern and role of individual RC histone H3 genes in Caenorhab-ditis elegans and compares them to the histone variant, H3.3. The findings reveal a tightly regulated epigenome landscape change from the germline to embryos, showing that a change from a H3.3-to H3-enriched epigenome restricts developmental plasticity and uncovers distinct roles for individual H3 genes in regulating germline chromatin.