Histone variants and cellular plasticity

• Canonical histone proteins are replaced with specific variants before and during periods of cellular transition.
• Histone variants regulate cellular plasticity during development and in the adult nervous system.
• Variants TH2A, TH2B, H2A.Z, and H3.3 facilitate cellular plasticity in early development.
• Variants H2A.X, H3.3, and macroH2A inhibit developmental plasticity following cellular differentiation.
• Variants H3.3, H2A.Z, and H2B.E regulate cellular plasticity in the adult nervous system.

The broad diversity of cell types within vertebrates arises from a unique genetic blueprint by combining intrinsic cellular information with developmental and other extrinsic signals. Lying at the interface between cellular signals and the DNA is the chromatin, a dynamic nucleoprotein complex that helps to mediate gene regulation. The most basic subunit of chromatin, the nucleosome, consists of DNA wrapped around histones, a set of proteins that play crucial roles as scaffolding molecules and regulators of gene expression. Growing evidence indicates that canonical histones are commonly replaced by protein variants before and during cellular transitions. We highlight exciting new results suggesting that histone variants are essential players in the control of cellular plasticity during development and in the adult nervous system.