NBS1-CtIP-mediated DNA end resection suppresses cGAS binding to micronuclei.

Area of Science:

• Immunology
• Molecular Biology
• Genetics

Background:

• Cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS) activation is linked to defects in DNA damage repair and signaling (DDR) factors.
• The precise role of DDR factors in regulating cGAS activation by micronuclear DNA remains unclear.

Purpose of the Study:

• To investigate the role of Nijmegen breakage syndrome 1 (NBS1) protein and its associated factors in regulating cGAS activation in response to micronuclear DNA.
• To elucidate the mechanism by which NBS1 prevents cGAS from binding to micronuclear DNA.

Main Methods:

• Utilized a cGAS tripartite system to assess cGAS activation.
• Investigated protein interactions between NBS1, ATM, and CtIP in the context of micronuclear DNA.
• Analyzed the binding of NBS1 to micronuclear DNA and its effect on DNA end resection.

Main Results:

• NBS1 protein, in coordination with ATM and CtIP, functions as an upstream regulator preventing cGAS binding to micronuclear DNA.
• NBS1 recruits ATM and CtIP to micronuclear DNA, where ATM stabilizes NBS1 binding and CtIP processes DNA ends, collectively inhibiting cGAS interaction.
• Cells lacking NBS1 exhibit increased cGAS recruitment to and activation by micronuclear DNA.

Conclusions:

• NBS1 and its partners ATM and CtIP play a crucial role in preventing aberrant cGAS activation by micronuclear DNA.
• These findings reveal a novel function of NBS1 beyond its canonical role in DNA double-strand break repair signaling.
• The study highlights the intricate interplay between DNA damage response pathways and innate immune signaling.