A puzzle regarding PRC2 has intrigued the Bracken lab and other scientists in the field for years: two forms (PRC2.1 and PRC2.2) exist in the cell but the Bracken lab previously showed that the two forms of PRC2 target the same regions of DNA and do the same job. So why do we need two versions?
A team of scientists led by those in Trinity College Dublin has discovered new mechanisms involved in establishing cellular identity, a process that ensures the billions of different cells in our bodies do the correct job. This new discovery in stem cells – a result so surprising that the team initially believed it to be an error in the lab – has potential translational impacts in cancer biology and associated targeted treatments.
The research focuses on the workings of Polycomb protein complexes, PRC1 and PRC2, which are studied by Professor Adrian Bracken and his team, based in Trinityâ€™s School of Genetics and Microbiology. PhD student, Ellen Tuck, describes these proteins as â€œstrict librariansâ€� inside cells. â€œPRC1 and PRC2 block access to certain areas of the genetic library, such that a neuron cell wonâ€™t have access to muscle genes, and it doesnâ€™t get confused in its cellular identity.â€�
The new discovery from the lab takes an exciting step towards answering this conundrum, as the team found that PRC2.1 and PRC2.2 recruit different forms of the PRC1 complex to DNA, thereby finally explaining why two versions are needed.
â€œThis took us by complete surprise. We initially thought there must have been a technical issue with the experiment, but multiple replications confirmed that we had in fact stumbled upon a fascinating new process that reshapes our understanding of the hierarchical workflow of Polycomb complexes. We were dancing around the lab,â€� said Dr Eleanor Glancy, recalling the evening the team finally realised what the data were telling them.
TRINITY COLLEGE DUBLIN,Molecular Cell
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