MSH6 regulates cGAS activity in antiviral and antitumor signaling pathways by governing its cytosolic/nuclear...

Area of Science:

• Immunology
• Molecular Biology
• Cancer Research

Background:

• Cytosolic cyclic GMP-AMP synthase (cGAS) is crucial for innate immunity against viral infections.
• Nuclear cGAS activity is inhibited to prevent autoimmune responses to self-DNA.
• The regulation of cGAS spatial distribution between cytosol and nucleus is vital for immune homeostasis but remains mechanistically unclear.

Purpose of the Study:

• To elucidate the molecular mechanism controlling cGAS localization and activity.
• To investigate the role of MSH6 in regulating cGAS nuclear import.
• To explore the therapeutic implications of targeting MSH6 in cancer immunotherapy.

Main Methods:

• Protein-protein interaction studies to identify cGAS interactors.
• Immunofluorescence and cell fractionation to assess cGAS localization.
• In vitro assays to measure cGAS enzymatic activity.
• Tumor models to evaluate the impact of MSH6 deficiency on antitumor immunity.

Main Results:

• MSH6 was identified as a novel regulator that promotes cGAS nuclear localization.
• MSH6 enhances cGAS association with importin-α, facilitating nuclear import.
• Nuclear cGAS localization mediated by MSH6 reduces cGAS condensation and enzymatic activity.
• MSH6 deficiency in tumor cells potentiates antitumor immunity and tumor eradication by modified vaccinia virus Ankara.

Conclusions:

• MSH6 controls cGAS localization and activity, impacting immune responses.
• Targeting MSH6 offers a potential therapeutic strategy for MSH6-mutated tumors via cGAS-dependent pathways.
• Understanding cGAS regulation by MSH6 provides insights into immune homeostasis and cancer therapy.