NINJ1 ubiquitination by TRIM72 protects against plasma membrane rupture and AKI-CKD progression

Abstract The progression of acute kidney injury (AKI) to chronic kidney disease (CKD) remains a major clinical challenge. It is primarily triggered by renal tubular epithelial cell (RTEC) death that leads to persistent sterile inflammation, maladaptive repair and irreversible renal fibrosis. A pivotal event in RTEC death is plasma membrane rupture (PMR), which leads to the release of Damage-Associated Molecular Patterns (DAMPs). In this study, we identified Tripartite Motif-Containing 72 (TRIM72) as a critical regulator of Ninjurin-1 (NINJ1), a key mediator of PMR. Using tubule-specific knockout mice ( Ninj1 fl/fl Ksp cre and Hmgb1 fl/fl Ksp cre ) in a folic acid-induced AKI-CKD model, together with in vitro RTEC and immune cell assays, we delineated the TRIM72-NINJ1-HMGB1 signaling axis. We found that TRIM72 functions as an E3 ubiquitin ligase that targets NINJ1 at lysine 111 for proteasomal degradation, thereby restraining NINJ1-mediated PMR. Loss of TRIM72 stabilized NINJ1, exacerbated RTEC membrane rupture, and amplified the release of HMGB1. The resulting HMGB1 release propagated inflammation by promoting both macrophage-myofibroblast transition (MMT) and neutrophil extracellular trap (NET) formation, two major drivers of renal fibrosis. Consistently, tubule-specific deletion of either Ninj1 or Hmgb1 markedly attenuated the progression from AKI to CKD. Together, these findings establish the TRIM72-NINJ1-HMGB1 cascade as a central molecular pathway dictating the fate of injured RTECs and highlight TRIM72 as a promising therapeutic target for halting the transition from AKI to CKD.