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Abstract: SA-PO500

Targeted Transgenic Expression of Catalase to Mitochondria Reduces Reactive Oxygen Species and Ameliorates Diabetic Nephropathy in BTBR ob/ob Mice

Session Information

Category: Diabetic Kidney Disease

  • 601 Diabetic Kidney Disease: Basic

Authors

  • Li, Xianwu, University of Washington, Seattle, Washington, United States
  • Batorsky, Anna, University of Washington, Seattle, Washington, United States
  • Holland, Alexander Lucas, University of Washington, Seattle, Washington, United States
  • Rabinovitch, Peter S., University of Washington, Seattle, Washington, United States
  • Hudkins, Kelly L., University of Washington, Seattle, Washington, United States
  • Alpers, Charles E., University of Washington, Seattle, Washington, United States
Background


Diabetes induced mitochondrial dysfunction from increased generation of reactive oxygen species (ROS) is pathogenic for diabetic complications including diabetic nephropathy (DN). Catalase is a major scavenger of ROS and prevents tissue damage from oxidative stress. To explore pathogenic mechanisms and to test a targeted ROS reduction strategy for treating DN, we created diabetic BTBR ob/ob mice with inducible transgenic human catalase expressed only in mitochondria (mCAT) to determine the efficacy of reducing mitochondrial ROS in a murine model of DN.

Methods

Transgenic Rosa 26 mice containing loxP-stop-loxP-mCAT and tamoxifen-inducible Cre mice (B6.129-Gt(ROSA)26Sortm1(cre/ERT2)Tyj/J) were backcrossed into the BTBR mouse strain. The heterozygous ob/+ mice of each strain were crossed to obtain ob/ob double transgenic mice. At 16 weeks of age, the mCAT gene expression was induced by oral administration of tamoxifen and the induced mice were referred as mCAT ob/ob. The double transgenic mice without tamoxifen treatment were used as control group (Rosa ob/ob). Fasting glucose levels were monitored and timed (6 hour) urine samples were collected at weeks of 18 and 24. At the end of the study (24wks), mice were sacrificed and blood and organs harvested.

Results

Both mCAT ob/ob and Rosa ob/ob were hyperglycemic (499.2 vs 566.7mg/dl) and obese. mCAT ob/ob mice exhibited a significant decrease in albumin-creatinine ratio (ACR) compared with control mice (196.1 vs 305.9 ug/mg, p < 0.05). Morphometry revealed a marked reduction of mesangial matrix accumulation assessed by collagen IV staining (15.4 vs 22.3% glomerular tuft area, p < 0.01). mCAT expression also reduced the extent of mesangiolysis vs. control mice (20.5 vs 29.4% of glomeruli, p < 0.05). The levels of urinary 8OHdG (a DNA/RNA marker of oxidative stress) were also reduced in mCAT ob/ob mice vs. Rosa ob/ob (72.9 vs 129.2 ng/mg creatinine, p < 0.05). Measures of podocyte density are pending.

Conclusion

Reduction of ROS specifically in mitochondria by targeted expression of catalase in BTBR ob/ob mice ameliorates albuminuria and dramatically improves mesangial expansion and mesangiolysis, thereby offering a new approach for DN therapeutics.

Funding

  • NIDDK Support