SIRT1 deacetylates APE1 and regulates cellular base excision repair

Area of Science:

• Molecular Biology
• Biochemistry
• Genetics

Background:

• Apurinic/apyrimidinic endonuclease-1 (APE1) is crucial for base excision repair (BER).
• SIRTUIN1 (SIRT1) is a protein deacetylase with known roles in cellular processes.
• The interaction and regulation between APE1 and SIRT1 in DNA repair remain largely unexplored.

Purpose of the Study:

• To investigate whether APE1 is a direct target of SIRT1.
• To elucidate the role of SIRT1-mediated deacetylation of APE1 in DNA repair.
• To understand how SIRT1 regulates APE1's function in response to genotoxic stress.

Main Methods:

• Co-immunoprecipitation assays to assess protein-protein interactions.
• In vitro and in vivo deacetylation assays using purified proteins and cell lysates.
• Western blotting to detect acetylation and deacetylation modifications.
• Cell viability assays and DNA damage assessment following gene knockdown or overexpression.
• Analysis of protein complex formation and enzyme activity assays.

Main Results:

• SIRT1 directly associates with and deacetylates APE1 at lysines 6 and 7.
• Genotoxic stress increases APE1 acetylation, which is counteracted by increased SIRT1 expression.
• SIRT1 knockdown sensitizes cells to genotoxic stress, an effect rescued by APE1 overexpression.
• SIRT1 activation enhances APE1 binding to XRCC1 and its DNA repair activity, while inhibition reduces it.

Conclusions:

• APE1 is identified as a novel protein target of SIRT1.
• SIRT1 plays a critical role in maintaining genomic integrity by regulating the BER pathway via APE1.
• Targeting the SIRT1-APE1 interaction could offer therapeutic strategies for genotoxic stress-induced conditions.