The E3 ubiquitin ligase MARCH9 alleviates pyroptosis by regulating NLPR3 ubiquitination following myocardial ischemia reperfusion.

NLRP3, a member of the NOD-like receptor family, mediates pyroptosis via inflammasome activation, contributing significantly to myocardial ischemia-reperfusion (MI/R) injury. However, the molecular mechanisms remain unclear. This study aimed to elucidate the mechanisms underlying NLRP3 inflammasome activation and its role in pyroptotic myocyte death following MI/R injury, with a particular focus on the effects of MARCH9, an E3 ubiquitin ligase that encodes a RING finger domain. In our in vivo experiments, we established an MI/R injury model by ligating the anterior descending branch of the coronary artery in mice. Cardiac tissues were analyzed using various methods, including proteomic analysis, TTC and Evan's blue dual-dye staining, immunohistochemical staining (F4/80, CD11b and Ly6G), and immunofluorescent staining (GSDMD-N). Western blotting was also performed to assess the expression of key pyroptosis-related proteins, such as MARCH9, NLRP3, caspase-1, GSDMD-N, and AIM2. In vitro studies in H9C2 and HEK293 cell lines involved western blotting, co-immunoprecipitation, and immunofluorescent staining to examine protein interactions and functional domains. Our findings reveal that MARCH9 plays a key regulatory role in NLRP3 inflammasome activation and pyroptosis during MI/R injury. MARCH9 was identified as an E3 ubiquitin ligase that interacts with NLRP3, promoting its K48-linked polyubiquitination and subsequent proteasomal degradation. This process inhibits NLRP3 activation, thereby mitigating pyroptosis and reducing myocardial injury. In conclusion, MARCH9 suppresses pyroptosis by modulating NLRP3 ubiquitination in response to MI/R injury, highlighting its potential as a novel cardioprotective target for therapeutic intervention.