RNF111-facilitated neddylation potentiates cGAS-mediated antiviral innate immune response.

Area of Science:

• Immunology
• Molecular Biology
• Cellular Signaling

Background:

• The cytosolic DNA sensor cyclic GMP-AMP (cGAMP) synthetase (cGAS) is vital for initiating innate immune responses against pathogens.
• Tight regulation of cGAS activity is essential for maintaining immune homeostasis during antiviral responses.

Purpose of the Study:

• To investigate the role of neddylation modification in the activation of the cGAS-STING signaling pathway.
• To identify the specific neddylation enzymes involved in regulating cGAS activity.
• To elucidate the mechanism by which neddylation impacts cGAS function and antiviral immunity.

Main Methods:

• Utilized the neddylation inhibitor MLN4924 to block the neddylation pathway.
• Employed genetic deficiency models for Nedd8 E2 enzyme Ube2m and Nedd8 E3 ligase Rnf111.
• Performed mass spectrometry to identify neddylation sites on cGAS.
• Assessed cGAS dimerization, DNA-binding ability, and downstream cytokine induction.

Main Results:

• Blocking neddylation significantly impaired type I interferon and proinflammatory cytokine induction, dependent on Ube2m.
• Rnf111 deficiency attenuated DNA-triggered cGAS activation, confirming it as the Nedd8 E3 ligase for cGAS.
• Lys231 and Lys421 were identified as key neddylation sites on human cGAS.
• Rnf111-mediated polyneddylation of cGAS promoted its dimerization and enhanced DNA binding, activating the cGAS-STING pathway.
• Mice deficient in Ube2m or Rnf111 showed impaired innate immunity and increased susceptibility to HSV-1 infection.

Conclusions:

• The Ube2m-Rnf111 neddylation axis is essential for promoting cGAS-STING pathway activation.
• Neddylation modification plays a critical role in regulating innate immune responses and antiviral defense.
• This study uncovers a novel regulatory mechanism for cGAS-STING signaling.