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Examination of Proteins Bound to Nascent DNA in Mammalian Cells Using BrdU-ChIP-Slot-Western Technique
Published on: January 14, 2016
CDYL1-dependent decrease in lysine crotonylation at DNA double-strand break sites functionally uncouples
Enas R Abu-Zhayia1, Laila A Bishara1, Feras E Machour1
1Department of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel.
Abstract:
Previously, we showed that CDYL1 is recruited to DNA double-strand breaks (DSBs) to promote homologous recombination (HR) repair and foster transcriptional silencing. However, how CDYL1 elicits DSB-induced silencing is not fully understood. Here, we identify a CDYL1-dependent local decrease in the transcriptionally active marks histone lysine crotonylation (Kcr) and crotonylated lysine 9 of H3 (H3K9cr) at AsiSI-induced DSBs, which correlates with transcriptional silencing. Mechanistically, we reveal that CDYL1 crotonyl-CoA hydratase activity counteracts Kcr and H3K9cr at DSB sites, which triggers the eviction of the transcription elongation factor ENL and fosters transcriptional silencing. Furthermore, genetic inhibition of CDYL1 hydratase activity blocks the reduction in H3K9cr and alleviates DSB-induced silencing, whereas HR efficiency unexpectedly remains intact. Therefore, our results functionally uncouple the repair and silencing activity of CDYL1 at DSBs. In a broader context, we address a long-standing question concerning the functional relationship between HR repair and DSB-induced silencing, suggesting that they may occur independently.
Insights
CDYL1
Area of Science:
- Molecular Biology
- Epigenetics
- DNA Repair
Background:
- CDYL1 protein is known to be recruited to DNA double-strand breaks (DSBs).
- CDYL1 promotes homologous recombination (HR) repair and transcriptional silencing at DSBs.
- The precise mechanism by which CDYL1 induces silencing remains unclear.
Purpose of the Study:
- To elucidate the mechanism of CDYL1-mediated transcriptional silencing at DSBs.
- To investigate the role of CDYL1's enzymatic activity in DSB-induced silencing.
- To determine the relationship between CDYL1's repair and silencing functions.
Main Methods:
- Analysis of histone lysine crotonylation (Kcr) and H3K9cr at DSBs.
- Assessing the impact of CDYL1 on transcription elongation factor ENL.
- Utilizing genetic inhibition of CDYL1's hydratase activity.
- Evaluating homologous recombination (HR) efficiency.
Main Results:
- CDYL1 recruitment to DSBs leads to decreased H3K9cr, correlating with transcriptional silencing.
- CDYL1's crotonyl-CoA hydratase activity removes H3K9cr, causing ENL eviction and silencing.
- Inhibiting CDYL1's hydratase activity prevents H3K9cr reduction and alleviates silencing.
- HR efficiency is unaffected by the inhibition of CDYL1's hydratase activity.
Conclusions:
- CDYL1's functions in DNA repair and transcriptional silencing at DSBs are separable.
- CDYL1's enzymatic activity is crucial for DSB-induced silencing, but not for HR.
- Homologous recombination repair and DSB-induced silencing may operate independently.
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