The Polycomb repressive complex 2 (PRC2), initially identified in Drosophila several decades ago, was found to be a key controller of developmental genes. Subsequent research revealed that PRC2 alters chromatin structure to suppress the expression of specific genes.
This initial understanding of PRC2’s ancestral function — functioning primarily to control genes during development — was challenged when it was found to be active in unicellular organisms, in which no development takes place.
PRC2’s Ancestral Role and Evolution
A first hint at PRC2’s original role came from studies in red algae, which found PRC2 left its methylation mark on transposons – jumping genes that move around the genome. Frederic Berger and his research group at the Gregor Mendel Institute of Molecular Plant Biology (GMI) decided to follow this cue and, in an international collaboration with researchers at Freie Universität Berlin, University of Cambridge, Nantes University, the National Institute of Genetics (Japan) and Monash University, investigated how PRC2 acts in a range of eukaryotes.
Investigating PRC2 Across Eukaryotes
To understand PRC2’s role in the ancestors of eukaryotes, the researchers studied the genomes of three widely distant lineages of eukaryotes: plants, SAR, and opisthokonts, the lineage to which humans and fungi belong.
All of these eukaryotes contain transposons, mobile genetic elements that can excise themselves from
Reference: “The Polycomb repressive complex 2 deposits H3K27me3 and represses transposable elements in a broad range of eukaryotes” by Tetsuya Hisanaga, Facundo Romani, Shuangyang Wu, Teresa Kowar, Yue Wu, Ruth Lintermann, Arie Fridrich, Chung Hyun Cho, Timothée Chaumier, Bhagyshree Jamge, Sean A. Montgomery, Elin Axelsson, Svetlana Akimcheva, Tom Dierschke, John L. Bowman, Takayuki Fujiwara, Shunsuke Hirooka, Shin-ya Miyagishima, Liam Dolan, Leila Tirichine, Daniel Schubert and Frédéric Berger, 21 September 2023, DOI: 10.1016/j.cub.2023.08.073