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BRCA2 prevents R-loop accumulation and associates with TREX-2 mRNA export factor PCID2
Vaibhav Bhatia1, Sonia I Barroso1, María L García-Rubio1
1Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla, Avenida Américo Vespucio s/n, 41092 Seville, Spain.
Nature
|June 5, 2014
Summary
Genome instability, linked to ageing and cancer, can arise from RNA-DNA hybrids called R-loops. The TREX-2 complex prevents this instability, while BRCA2 processes R-loops, highlighting their role in cancer-associated genome instability.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- Genome instability is a key factor in aging, cancer, and disease.
- Mutations in genes for pre-mRNA splicing and messenger ribonucleoprotein (mRNP) biogenesis/export can cause DNA damage and genome instability.
- R-loops, structures formed by DNA-RNA hybrids, frequently mediate this instability.
Purpose of the Study:
- To investigate the role of the human TREX-2 complex in maintaining genome integrity.
- To explore the relationship between TREX-2, R-loops, and genome instability.
- To determine the involvement of BRCA2 in R-loop processing and its connection to genome stability.
Main Methods:
- Depletion of TREX-2 subunits (PCID2, GANP, DSS1) and assessment of genome instability markers (γ-H2AX, 53BP1 foci, single-cell electrophoresis).
- Co-immunoprecipitation to study the association between BRCA2, DSS1, and PCID2.
- Detection of R-loops using an enhanced green fluorescent protein-tagged hybrid-binding domain of RNase H1 and the S9.6 antibody in TREX-2 and BRCA2-depleted cells.
Main Results:
- Depletion of TREX-2 subunits PCID2, GANP, and DSS1 leads to genome instability.
- BRCA2 interacts with PCID2 and is required for R-loop processing, as R-loops accumulate in BRCA2-depleted cells.
- R-loops were not detected in TREX-2-depleted cells, suggesting TREX-2's role in preventing their formation or facilitating their resolution.
Conclusions:
- The TREX-2 complex plays a crucial role in preventing genome instability.
- BRCA2 is essential for processing R-loops, which are prevalent in cells.
- R-loops represent a significant source of replication stress and may drive cancer-associated genome instability.
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