This is a preprint.
Identification of the main barriers to Ku accumulation in chromatin
- PMID: 38260538
- PMCID: PMC10802386
- DOI: 10.1101/2024.01.03.574002
Identification of the main barriers to Ku accumulation in chromatin
Update in
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Identification of the main barriers to Ku accumulation in chromatin.Cell Rep. 2024 Aug 27;43(8):114538. doi: 10.1016/j.celrep.2024.114538. Epub 2024 Jul 25. Cell Rep. 2024. PMID: 39058590 Free PMC article.
Abstract
Repair of DNA double strand breaks by the non-homologous end-joining pathway is initiated by the binding of Ku to DNA ends. Given its high affinity for ends, multiple Ku proteins load onto linear DNAs in vitro. However, in cells, Ku loading is limited to ~1-2 molecules per DNA end. The mechanisms enforcing this limit are currently unknown. Here we show that the catalytic subunit of the DNA-dependent protein kinase (DNA-PKcs), but not its protein kinase activity, is required to prevent excessive Ku entry into chromatin. Ku accumulation is further restricted by two mechanisms: a neddylation/FBXL12-dependent process which actively removes loaded Ku molecules throughout the cell cycle and a CtIP/ATM-dependent mechanism which operates in S-phase. Finally, we demonstrate that the misregulation of Ku loading leads to impaired transcription in the vicinity of DNA ends. Together our data shed light on the multiple layers of coordinated mechanisms operating to prevent Ku from invading chromatin and interfering with other DNA transactions.
Keywords: ATM; CtIP; DNA end resection; DNA repair; DNA-PKcs; FBXL12; Ku; MRN; NHEJ; Xenopus; neddylation.
Conflict of interest statement
Declaration of interests. The authors declare no competing interests.
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References
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- Blier P.R., Griffith A.J., Craft J., and Hardin J.A. (1993). Binding of Ku protein to DNA. Measurement of affinity for ends and demonstration of binding to nicks. J Biol Chem 268, 7594–7601. - PubMed
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