The splicing component ISY1 regulates APE1 in base excision repair

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Cellular genomes face constant threats from DNA damaging agents.
• Failure to repair DNA damage can lead to replication stress and genetic instability.
• Base excision repair (BER) is vital for removing oxidized or alkylated DNA bases, but its regulation is unclear.

Purpose of the Study:

• To investigate the regulatory mechanisms of the Base Excision Repair (BER) pathway.
• To identify novel factors involved in DNA damage response.
• To elucidate the role of splicing factor ISY1 in BER.

Main Methods:

• Investigated the interaction between ISY1 and apurinic/apyrimidinic endonuclease 1 (APE1).
• Assessed the effect of ISY1 on APE1's 5'-3' endonuclease activity using purified recombinant proteins.
• Reconstituted Base Excision Repair (BER) pathways in vitro to evaluate ISY1's impact.
• Examined ISY1 expression levels in response to oxidative DNA damage.

Main Results:

• ISY1 enhances the 5'-3' endonuclease activity of APE1.
• ISY1 expression is induced by oxidative damage, suggesting rapid BER enhancement.
• ISY1 and APE1 physically interact, with ISY1 improving APE1's recognition of abasic sites.
• ISY1 significantly boosts APE1 activity in both short- and long-patch BER pathways.

Conclusions:

• ISY1 acts as a novel regulator of the Base Excision Repair (BER) pathway.
• The ISY1-APE1 interaction is physiologically relevant, especially when APE1 levels are suboptimal.
• This study links pre-mRNA splicing machinery to DNA damage repair processes.