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The SWI/SNF chromatin remodeling complex helps resolve R-loop-mediated transcription-replication conflicts
Aleix Bayona-Feliu1,2, Sonia Barroso1, Sergio Muñoz1
1Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain.
Nature Genetics
|May 14, 2021
Summary
SWI/SNF complexes, particularly cBAF, resolve R-loop-mediated conflicts between transcription and replication. This chromatin remodeling mechanism protects genome integrity and prevents DNA breaks, crucial for cancer research.
Area of Science:
- Molecular Biology
- Cancer Biology
- Genetics
Background:
- ATP-dependent chromatin remodelers, like SWI/SNF, are frequently mutated in human cancers.
- BRG1 (SMARCA4) is a key ATPase subunit of SWI/SNF complexes and is often mutated in cancer.
- Genome instability is a hallmark of cancer, linked to processes including transcription, DNA replication, and repair.
Purpose of the Study:
- To investigate the role of SWI/SNF complexes in maintaining genome stability.
- To explore the connection between BRG1, R-loops, and transcription-replication conflicts.
- To uncover mechanisms by which chromatin remodeling impacts cancer genome integrity.
Main Methods:
- Depletion of BRG1 in mammalian cells.
- Analysis of R-loop formation and DNA breaks.
- Assessment of transcription-replication (T-R) conflicts.
- Immunofluorescence for FANCD2 foci to mark replication stress.
- Epistasis analysis of BRG1 depletion and FANCD2 silencing.
Main Results:
- BRG1 depletion increases R-loops and R-loop-dependent DNA breaks.
- BRG1 depletion exacerbates transcription-replication (T-R) conflicts.
- BRG1 colocalizes with R-loops and replication fork blocks.
- SWI/SNF complexes, especially cBAF, are critical for resolving R-loop-mediated T-R conflicts.
Conclusions:
- SWI/SNF complexes, particularly cBAF, play a vital role in resolving R-loop-mediated transcription-replication conflicts.
- This function of SWI/SNF contributes to the maintenance of genome integrity.
- Disruption of this chromatin remodeling mechanism represents a novel pathway through which SWI/SNF mutations can drive cancer development.
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