SWI/SNF complexes are required for full activation of the DNA-damage response

Area of Science:

• Cellular Biology
• Cancer Biology
• Genetics

Background:

• SWI/SNF complexes, containing BRG1 or BRM, are vital for mammalian development and frequently mutated in human cancers.
• Their precise tumor-suppressor mechanisms, particularly in DNA damage response (DDR), remain incompletely understood.

Purpose of the Study:

• To investigate the function of SWI/SNF complexes in the DNA-damage response (DDR).
• To elucidate the role of SWI/SNF in mitigating genotoxic stress and maintaining genomic stability.

Main Methods:

• Utilized shRNA to deplete BRG1 and BRM in cells.
• Exposed depleted cells to various genotoxic agents causing DNA double-strand breaks (DSBs).
• Analyzed DDR kinase activation (ATR-Chk1 vs. ATM-Chk2) and γH2AX induction.

Main Results:

• BRG1/BRM-depleted cells showed hypersensitivity to replication-associated DSBs but not IR-induced DSBs.
• SWI/SNF complexes preferentially activate the ATR-Chk1 pathway over ATM-Chk2.
• Depletion led to attenuated γH2AX induction with etoposide and nucleoplasmic bridges in normal fibroblasts.

Conclusions:

• SWI/SNF complexes are critical for DDR, specifically attenuating replicative stress and preventing genomic instability.
• These findings suggest SWI/SNF's tumor-suppressor activity is linked to DDR pathways.
• Understanding this role may guide chemotherapy selection for SWI/SNF-deficient tumors.