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Updated: Dec 18, 2025
Characterizing DNA Repair Processes at Transient and Long-lasting Double-strand DNA Breaks by Immunofluorescence Microscopy
Published on: June 8, 2018
Synergy between SIRT1 and SIRT6 helps recognize DNA breaks and potentiates the DNA damage response and repair in
Fanbiao Meng1,2, Minxian Qian1,3, Bin Peng3
1Shenzhen Key Laboratory for Systemic Aging and Intervention, National Engineering Research Center for Biotechnology (Shenzhen), Shenzhen University Health Science Center, Shenzhen, China.
Abstract:
The DNA damage response (DDR) is a highly orchestrated process but how double-strand DNA breaks (DSBs) are initially recognized is unclear. Here, we show that polymerized SIRT6 deacetylase recognizes DSBs and potentiates the DDR in human and mouse cells. First, SIRT1 deacetylates SIRT6 at residue K33, which is important for SIRT6 polymerization and mobilization toward DSBs. Then, K33-deacetylated SIRT6 anchors to γH2AX, allowing its retention on and subsequent remodeling of local chromatin. We show that a K33R mutation that mimics hypoacetylated SIRT6 can rescue defective DNA repair as a result of SIRT1 deficiency in cultured cells. These data highlight the synergistic action between SIRTs in the spatiotemporal regulation of the DDR and DNA repair in humans and mice.
Insights
Polymerized SIRT6 deacetylase recognizes DNA double-strand breaks (DSBs) and enhances the DNA damage response (DDR). SIRT1-mediated deacetylation at K33 is crucial for SIRT6
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- The precise initial recognition of DNA double-strand breaks (DSBs) within the DNA damage response (DDR) remains incompletely understood.
- The sirtuin family of proteins plays critical roles in cellular regulation, including DNA repair pathways.
Purpose of the Study:
- To elucidate the mechanism by which SIRT6 recognizes DSBs and contributes to the DDR.
- To investigate the role of SIRT1 in regulating SIRT6 activity and localization during the DDR.
Main Methods:
- Utilized human and mouse cell lines.
- Investigated protein-protein interactions and post-translational modifications (acetylation) of SIRT6.
- Examined the localization of SIRT6 to DSB sites using markers like γH2AX.
- Employed site-directed mutagenesis (K33R) to mimic hypoacetylated SIRT6.
Main Results:
- Demonstrated that polymerized SIRT6 directly recognizes DSBs and potentiates the DDR.
- Showed that SIRT1 deacetylates SIRT6 at lysine 33 (K33), a critical step for SIRT6 polymerization and recruitment to DSBs.
- Confirmed that K33-deacetylated SIRT6 binds to γH2AX, facilitating chromatin remodeling at DSB sites.
- A K33R SIRT6 mutant rescued DNA repair defects in cells deficient in SIRT1.
Conclusions:
- SIRT1 and SIRT6 act synergistically to regulate the spatiotemporal dynamics of the DDR and DNA repair.
- Deacetylation of SIRT6 by SIRT1 is a key regulatory event for DSB recognition and repair.
- These findings provide novel insights into the molecular mechanisms governing DNA repair pathways.
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