Over the course of development, PRC2s function moved from repressing transposons to quelching protein-coding genes. Credit: GMI
Examining PRC2 Across Eukaryotes
To understand PRC2s function in the forefathers of eukaryotes, the researchers studied the genomes of three commonly distant lineages of eukaryotes: plants, SAR, and opisthokonts, the family tree to which humans and fungis belong.
All of these eukaryotes contain transposons, mobile genetic elements that can excise themselves from DNA and insert at novel areas– a possible risk to genome stability, for this reason why transposons have actually to be silenced. In mutant diatoms, bryophytes, and red algae the removal of PRC2 activity caused the loss of silencing of transposable elements.
Implications and findings
” These findings show that PRC2 represses transposable components in these far-off lineages, which specifies this as a function that arose in the ancestor of all 3 lineages. PRC2s origin was most likely to mostly defend the genome from invasion by transposons. This ancestral function is an extensive modification in paradigm,” states Frederic Berger, group leader at GMI and the studys corresponding author.
Over the course of evolution, however, the function of PRC2 gradually shifted from quelching transposons to repressing protein-coding genes, its originally explained role. In land plants, the scientists discover “fossil TEs” to still be targets for PRC2, which then silences genes in the area.
” In blooming plants, like Arabidopsis, which evolved more just recently, residues of TEs are still present and recruit PRC2 to silence close-by genes”, explains Tetsuya Hisanaga, a postdoctoral scientist in the Berger group and the studys very first author. “We hypothesize that in Arabidopsis, some TEs have actually been domesticated, ending up being components involved in regulating protein-coding genes.”
Recommendation: “The Polycomb repressive complex 2 deposits H3K27me3 and quelches transposable elements in a broad series 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, Current Biology.DOI: 10.1016/ j.cub.2023.08.073.
Recent research study has actually redefined the primary role of Polycomb repressive complex 2 (PRC2) from managing developmental genes to protecting the genome against transposon intrusion. This ancestral function, constant throughout numerous eukaryotes, evolved over time, resulting in PRC2s present role in silencing protein-coding genes, especially in flowering plants like Arabidopsis.
The Polycomb repressive complex 2 (PRC2), at first recognized in Drosophila several years ago, was found to be an essential controller of developmental genes. Subsequent research revealed that PRC2 modifies chromatin structure to reduce the expression of specific genes.
This preliminary understanding of PRC2s ancestral function– working primarily to control genes throughout advancement– was challenged when it was discovered to be active in unicellular organisms, in which no development takes place.
PRC2s Ancestral Role and Evolution
A first mean PRC2s initial function originated from research studies in red algae, which discovered PRC2 left its methylation mark on transposons– jumping genes that walk 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 a worldwide cooperation with scientists at Freie Universität Berlin, University of Cambridge, Nantes University, the National Institute of Genetics (Japan) and Monash University, examined how PRC2 acts in a series of eukaryotes.