CDYL1-dependent decrease in lysine crotonylation at DNA double-strand break sites functionally uncouples transcriptional silencing and repair.

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 Asi SI-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. [Display omitted] • Local decrease in Kcr at DSBs correlates with transcriptional silencing • CDYL1 crotonyl-CoA hydratase activity downregulates Kcr at DSBs • Kcr reduction at DSBs promotes ENL eviction and fosters transcriptional silencing • CDYL1 roles in DSB-induced silencing and HR repair are functionally uncoupled Abu-Zhaiya et al. identify a CDYL1-dependent decrease in lysine crotonylation at DSB sites that fosters transcriptional silencing. It is widely accepted that DSB-induced silencing is prerequisite for timely DSB repair. Here, the authors challenge the current dogma and provide evidence that functionally uncouple DSB-induced silencing and repair, suggesting that they occur independently. [ABSTRACT FROM AUTHOR]