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Abstract: FR-PO336

Karyomegalic Interstitial Nephritis Is Triggered by Oxidative Stress Caused by Mitochondrial Deficiency in FAN1-Deficient Proximal Tubule Cells

Session Information

Category: Genetic Diseases of the Kidneys

  • 1102 Genetic Diseases of the Kidneys: Non-Cystic


  • Airik, Merlin, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
  • Huynh, Amy B., University of Pittsburgh, Pittsburgh, Pennsylvania, United States
  • Goetzman, Eric S., Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania, United States
  • Airik, Rannar, University of Pittsburgh, Pittsburgh, Pennsylvania, United States

Karyomegalic interstitial nephritis (KIN) is a genetic form of chronic kidney disease (CKD) caused by mutations in FAN1, a DNA repair enzyme. Accordingly, accumulation of DNA damage in the kidney tubular epithelium is a hallmark of KIN. However, the source and nature of the agent(s) responsible for inducing DNA lesions that trigger KIN have remained elusive. Here, we show using in vivo and in vitro models, that mitochondrial-derived ROS is critical for inducing KIN pathogenesis.


KIN was induced in 12-week-old Fan1 KO mice by employing 2 cisplatin injury models: one mimicking AKI (weekly 2 x 4 mg/kg cisplatin), and another CKD (weekly 5 x 2 mg/kg cisplatin). Coincident with cisplatin, mice were administered a novel mitochondrial ROS scavenger at a dose of 10 mg/kg. Histological analysis was performed using PAS and HE. Markers of tubular injury, DNA damage and fibrosis were assessed by IF and IHC. Human kidney proximal tubular cells (PTECs) were used to model FAN1 loss of function in vitro. RNA-seq analysis was performed to identify transcriptional changes in KIN. Mitochondrial OXPHOS was measured using the Oroboros Oxygraph-2k System. Metabolite measurements were preformed using YSI 7100 Bioanalyzer.


Transcriptional profiling of kidneys with KIN revealed a significant downregulation of genes involved in mitochondrial energy metabolism - OXPHOS, fatty acid oxidation (FAO) and peroxisomal function. Metabolic analysis of FAN1 KO PTECs showed a defect in respiratory chain, increased oxidative stress and a shift to increased lactate secretion. Similarly, Fan1 KO kidneys revealed marked increase in oxidative DNA damage (8-OHdG), lipid peroxidation (4-HNE) and tubular lipotoxicity (OilRedO) after AKI or CKD. Treatment with mitochondrial ROS scavenger reduced the level of oxidative lesions in Fan1 KO kidneys, mitigated tubular damage and blocked the formation of KIN.


Loss of FAN1 causes defective mitochondrial metabolism and increased ROS generation in the kidney which give rise to oxidative DNA lesions and results in KIN. Blocking mitochondrial ROS protects Fan1 KO kidneys from DNA damage accumulation, mitigates tubular injury and improves kidney function in mice.


  • NIDDK Support