AI Article Synopsis
- The nucleolus is important for ribosomal RNA transcription but how this process is regulated within its liquid-like compartments is not well understood.
- Researchers used advanced tracking methods to show that active RNA polymerase I (Pol I) clusters in the nucleolus can suppress transcription through phase separation.
- A mutation in Pol I linked to a craniofacial disorder interferes with normal transcription by competing with functional Pol I, leading to changes in the nucleolus that further inhibit the process.
Article Abstract
The nucleolus is a nuclear body with multiphase liquid droplets for ribosomal RNA (rRNA) transcription. How rRNA transcription is regulated in the droplets remains unclear. Here, using single-molecule tracking of RNA polymerase I (Pol I) and chromatin-bound upstream binding factor (UBF), we reveal suppression of transcription with phase separation. For transcription, active Pol I formed small clusters/condensates that constrained rDNA chromatin in the nucleolus fibrillar center (FC). Treatment with a transcription inhibitor induced Pol I to dissociate from rDNA chromatin and to move like a liquid within the nucleolar cap that transformed from the FC. Expression of a Pol I mutant associated with a craniofacial disorder inhibited transcription by competing with wild-type Pol I clusters and transforming the FC into the nucleolar cap. The cap droplet excluded an initiation factor, ensuring robust silencing. Our findings suggest a mechanism of rRNA transcription suppression via phase separation of intranucleolar molecules governed by Pol I.
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Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7556839 | PMC |
| http://dx.doi.org/10.1126/sciadv.abb5953 | DOI Listing |
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