Nuclear IMPDH2 controls the DNA damage response by modulating PARP1 activity

Area of Science:

• Molecular Biology
• Cancer Research
• Biochemistry

Background:

• Nuclear metabolism and DNA damage response are linked, but molecular mechanisms are unclear.
• Triple-negative breast cancer (TNBC) is prone to DNA damage.
• Inosine monophosphate dehydrogenase 2 (IMPDH2) is key in purine synthesis.

Purpose of the Study:

• To investigate the role of IMPDH2 in the DNA damage response within TNBC.
• To elucidate the molecular crosstalk between nuclear metabolism and DNA repair pathways.
• To identify novel therapeutic targets for TNBC.

Main Methods:

• Chromatin enrichment analysis of IMPDH2 in TNBC.
• Assessment of DNA damage accumulation upon IMPDH2 repression.
• Investigation of IMPDH2 interaction with PARP1 and its effect on NAD+ levels.
• Cell death assays under different IMPDH2 nuclear localization conditions.

Main Results:

• IMPDH2 is enriched on chromatin in TNBC, dependent on DNA damage.
• IMPDH2 repression leads to increased DNA damage.
• Nuclear IMPDH2 modulates PARP1 activity by controlling nuclear NAD+ availability.
• Nuclear sequestration of IMPDH2 causes NAD+ depletion, PARP1 cleavage, and cell death.

Conclusions:

• IMPDH2 has a non-canonical nuclear function in regulating DNA damage response.
• IMPDH2 acts as a critical link between nuclear metabolism and DNA repair.
• Targeting IMPDH2 nuclear function may offer a therapeutic strategy for TNBC.