The cytosolic
DNA sensor
cyclic GMP-AMP (
cGAMP)
synthetase (cGAS) has emerged as a fundamental component fueling the anti-pathogen immunity. Because of its pivotal role in initiating innate immune response, the activity of cGAS must be tightly fine-tuned to maintain immune homeostasis in
antiviral response. Here, we reported that neddylation modification was indispensable for appropriate cGAS-
STING signaling activation. Blocking neddylation pathway using neddylation inhibitor
MLN4924 substantially impaired the induction of
type I interferon and proinflammatory
cytokines, which was selectively dependent on Nedd8 E2
enzyme Ube2m. We further found that deficiency of the Nedd8
E3 ligase Rnf111 greatly attenuated
DNA-triggered cGAS activation while not affecting
cGAMP induced activation of
STING, demonstrating that Rnf111 was the Nedd8
E3 ligase of cGAS. By performing mass spectrometry, we identified Lys231 and Lys421 as essential neddylation sites in human cGAS. Mechanistically, Rnf111 interacted with and polyneddylated cGAS, which in turn promoted its dimerization and enhanced the
DNA-binding ability, leading to proper cGAS-
STING pathway activation. In the same line, the Ube2m or Rnf111 deficiency mice exhibited severe defects in innate immune response and were susceptible to HSV-1
infection. Collectively, our study uncovered a vital role of the Ube2m-Rnf111 neddylation axis in promoting the activity of the cGAS-
STING pathway and highlighted the importance of neddylation modification in
antiviral defense.