RING1 dictates GSDMD-mediated inflammatory response and host susceptibility to pathogen infection.

RING1 is an E3 ligase component of the polycomb repressive complex 1 (PRC1) with known roles in chromatin regulation and cellular processes such as apoptosis and autophagy. However, its involvement in inflammation and pyroptosis remains elusive. Here, we demonstrate that human RING1, not RING2, promotes K48-linked ubiquitination of Gasdermin D (GSDMD) and acts as a negative regulator of pyroptosis and bacterial infection. Indeed, we showed that loss of Ring1 increased S. typhimurium infectious load and mortality in vivo. Though RING1 deletion initially reduced M. tuberculosis (Mtb) infectious load in vivo, increased lung inflammation and impaired immune defense responses were later observed. Moreover, Ring1 knockout exacerbated acute sepsis induced by lipopolysaccharide (LPS) in vivo. Mechanistically, RING1 directly interacts with GSDMD and ubiquitinates the K51 and K168 sites of GSDMD for K48-linked proteasomal degradation, thereby inhibiting pyroptosis. Inhibition of RING1 E3 ligase activity by direct mutation or with the use of small molecule inhibitors increased GSDMD level and cell death during pyroptosis. Our findings reveal that RING1 dictates GSDMD-mediated inflammatory response and host susceptibility to pathogen infection, highlighting RING1 as a potential therapeutic target for combating infectious diseases.