Polycomb Group Systems in Fungi: New Models for Understanding Polycomb Repressive Complex 2.

Polycomb group (PcG) proteins form multiple complexes that direct assembly of transcriptionally repressed chromatin, an essential process for multicellular development. Recent studies in plants and animals have uncovered surprising complexity in the form of multiple, variant PcG complexes governed by an extensive regulatory network. PcG proteins are absent from major yeast models, but recent research revealed minimal PcG systems in several well-studied fungi. In both animals and fungi, PcG complexes are responsive to local chromatin structure, but important aspects of PcG regulation remain unknown. Moreover, how PcG complexes repress transcription is poorly understood. The emergence of new fungal models to study PcG proteins is an important development that will accelerate understanding of this important chromatin regulation pathway.