ZBP1 Promotes RIPK1-Dependent Apoptosis in Aristolochic Acid Nephropathy

Aristolochic acid nephropathy (AAN) is a progressive form of kidney disease marked by acute tubular injury and interstitial fibrosis, ultimately leading to end-stage renal disease (ESRD). Despite regulatory restrictions, aristolochic acid (AA) remains a global health threat due to its presence in traditional herbal medicines. While mitochondria-mediated apoptosis is a hallmark of AA-induced tubular epithelial cell (TEC) injury, the upstream molecular mechanisms remain unclear. Here, we identify Z-DNA-binding protein 1 (ZBP1) as a key mediator of AA-induced kidney injury. Using Zbp1 knockout (Zbp1-/-) and Zα domain-mutant (ZαMut) mice, we show that loss of ZBP1 or its Z-form nucleic acid sensing capability protects against AA-induced renal dysfunction, apoptosis, and inflammation. Mechanistically, aristolochic acid I (AAI) induces mitochondrial oxidative stress and release of mitochondrial DNA (mtDNA), which adopts a Z-conformation and is recognized by ZBP1. The ZBP1 binding subsequently promotes RHIM-dependent interaction with RIPK1, culminating in caspase-8 activation and apoptotic cell death. Notably, ZBP1-mediated cell death was abolished by RIPK1 kinase inhibition or mutation, but unaffected by Ripk3 or Mlkl deletion, revealing a mechanism distinct from RIPK3/MLKL-dependent necroptosis. These findings uncover a previously unrecognized ZBP1-RIPK1-caspase-8 signaling axis driving non-canonical apoptosis in AAN and suggest that targeting this pathway may provide a novel therapeutic approach for nephrotoxin-induced kidney injury.