ZBP1 promotes RIPK1-dependent apoptosis in aristolochic acid nephropathy.

Aristolochic acid nephropathy (AAN) is a progressive kidney disease marked by acute tubular injury and interstitial fibrosis that frequently advances to end-stage renal disease (ESRD). Despite regulatory restrictions, aristolochic acid (AA) continues to pose a global health risk due to persistent exposure through traditional herbal medicines. Although mitochondria-mediated apoptosis is a defining hallmark of AA-induced tubular epithelial cell (TEC) injury, the upstream molecular mechanisms remain poorly resolved. The present study identified Z-DNA-binding protein 1 (ZBP1) as a key mediator of AAI-induced kidney injury. Using Zbp1 knockout ( Zbp1 -/-) and Zα domain-mutant ( Zα Mut) mice, loss of ZBP1 or disruption of Z-form nucleic acid sensing conferred marked protection against AAI-induced renal dysfunction, apoptosis, and inflammation. Mechanistic analyses showed that aristolochic acid I (AAI) triggered mitochondrial oxidative stress and promoted mitochondrial DNA (mtDNA) release, after which mtDNA adopted a Z-conformation recognized by ZBP1. ZBP1 engagement then promoted RHIM-dependent association with RIPK1, leading to caspase-8 activation and apoptotic cell death. Notably, ZBP1-mediated cell death was abolished by RIPK1 kinase inhibition or mutation but remained unchanged after Ripk3 or Mlkl deletion, indicating a pathway distinct from RIPK3/MLKL-dependent necroptosis. These findings define a previously unrecognized ZBP1-RIPK1-caspase-8 signaling axis that drives non-canonical apoptosis in AAN and identify this pathway as a potential therapeutic target in nephrotoxin-induced kidney injury.