CARM1 regulates replication fork speed and stress response by stimulating PARP1

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• DNA replication forks face various stress conditions.
• The mechanisms cells use to manage replication stress are not fully understood.
• Understanding how cells choose stress response pathways is crucial.

Purpose of the Study:

• To investigate the role of CARM1 in DNA replication fork regulation.
• To elucidate the mechanism by which CARM1 influences replication fork speed and stress response.
• To identify the interaction partners of CARM1 at replication forks.

Main Methods:

• Assessing CARM1's association with replication forks.
• Measuring replication fork speed in CARM1-deficient cells.
• Investigating the roles of RECQ1 and RAD18 in CARM1-deficient cells.
• Analyzing CARM1's interaction with PARP1 and HPF1 in vitro and in vivo.
• Studying the effect of CARM1 on PARP1 activity and DNA binding.

Main Results:

• CARM1 associates with replication forks and reduces their speed, independent of its methyltransferase activity.
• Loss of CARM1 leads to faster replication forks, requiring RECQ1 and RAD18.
• CARM1 deficiency reduces fork reversal and increases single-stranded DNA gaps, enhancing replication stress tolerance.
• CARM1 interacts with PARP1, promoting PARylation at replication forks and stimulating PARP1 activity.

Conclusions:

• CARM1 acts as a key regulator of DNA replication fork speed and stress response.
• CARM1 and PARP1 form a regulatory module at replication forks, controlling fork dynamics and repair pathway choice.
• CARM1's stimulation of PARP1 activity is critical for slowing replication forks and promoting fork reversal during stress.