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Ribosomal RNA regulates chromosome clustering during mitosis
Kai Ma1,2,3, Man Luo1,2,3, Guanglei Xie1,2,3
1Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China.
Cell Discovery
|May 31, 2022
Summary
Ribosomal RNAs (rRNAs) bind to mitotic chromosomes, guided by Ki-67, preventing chromosome clustering during cell division. This discovery highlights a novel role for rRNAs in chromosome dynamics.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- Noncoding RNAs are known to interact with mitotic chromosomes.
- The specific roles and identities of these chromosome-associated RNAs during mitosis have remained largely unknown.
Purpose of the Study:
- To identify and characterize RNA species associated with condensed mitotic chromosomes.
- To elucidate the functional significance of these RNAs in mitotic chromosome organization and dynamics.
Main Methods:
- Analysis of RNA enrichment on mitotic chromosomes using mass spectrometry.
- Investigation of the interaction between ribosomal RNAs (rRNAs) and the Ki-67 protein.
- Functional assays involving RNA polymerase I inhibition and mutated Ki-67 to assess effects on chromosome dispersion.
Main Results:
- Ribosomal RNA (rRNA) precursors (45S, 32S, 30S) are highly enriched on mitotic chromosomes.
- Ki-67 protein binds to these chromosome-associated rRNAs via its FHA domain and repeat region.
- Suppression of chromosome-bound rRNAs leads to impaired mitotic chromosome dispersion and increased clustering.
Conclusions:
- Ribosomal RNAs play a critical role in maintaining mitotic chromosome structure.
- The Ki-67 protein acts as a key mediator, anchoring rRNAs to chromosomes to prevent premature chromosome clustering during prometaphase.
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