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Abstract: TH-PO861

XORs in the Genetic Susceptibility of Diabetic Kidney Disease in Mice

Session Information

Category: Diabetic Kidney Disease

  • 601 Diabetic Kidney Disease: Basic

Authors

  • Qi, Haiying, Mount Sinai school of medicine, Chatham, New Jersey, United States
  • Yu, Liping, Mount Sinai School of Medicine, New York, New York, United States
  • Wang, Qin, Icahn School of Medicine at Mount Sinai, New York, New York, United States
  • Daehn, Ilse S., Mount Sinai School of Medicine, New York, New York, United States
Background

Diabetic kidney disease (DKD) is the leading single cause of ESRD in the United States. Approximately 30% of diabetic patients develop DKD even with comparable blood glucose levels, indicating a significant genetic component for disease susceptibility. Differential susceptibilities to DKD have also been observed in well-defined strains of inbred mice. The underlying mechanisms that contribute to differential susceptibility to DKD are still poorly understood in both patients and rodent models.

The glomerulus is the primary site of injury with glomerular hypertrophy and podocyte depletion being the hallmarks for progressive DKD. Our work has demonstrated that ROS and mitochondrial oxidative stress damage accumulation, particularly in glomerular endothelial cells (GECs), leads to podocyte loss via endothelial-to-podocyte crosstalk in experimental mouse models of DKD and focal segmental glomerulosclerosis.

Methods

We used the BXD recombinant inbred panel to map genetic loci (QTL) associated with number of podocytes after long-term diabetes (6 months). We used parent strains inbred DBA/2J (D2) mice as susceptible, and C57BL/6J (B6) mice as resistant to diabetes-induced podocyte depletion associated with DKD susceptibility. Genetic mapping identified a cis-acting regulatory of the Xdh gene encoding xanthine dehydrogenase XDH/XO (xanthine oxidoreductase (XOR)). XORs catalyze the oxidation of purine substrates, xanthine and hypoxanthine, producing uric acid (UA) and are a major enzymatic source of cellular ROS. Both products have been demonstrated to be risk factors for cardiovascular diseases and DKD.

Results

Xdh expression in glomeruli and XO activity in serum were significantly increased in diabetic D2 mice, but not B6 resistant mice. XOR inhibition resulted in significantly reduced albuminuria, prevention of podocyte loss, as well as a reduction in DNA oxidation damage in the glomeruli of diabetic D2 mice. Using a luciferase reporter assay we examined if the two nucleotide variant could influence XOR activity. Our results show increased XOR activity of 293T cells when treated with high glucose (30mM) compared to controls. We have now generated mice with knock-in variants using CRISPR/Cas9 to determine their functional role in DKD susceptibility.

Conclusion

These data suggest that the identified promoter variant regulates XOR activity potentially linked to genetic susceptibility to DKD.

Funding

  • NIDDK Support