Abstract: SA-OR120

Genetic Deletion of Myo-Inositol Oxygenase (MIOX) Rescues ob/ob Mice from the Progression of Tubulo-Interstitial Injury

Session Information

Category: Diabetes

  • 501 Diabetes Mellitus and Obesity: Basic - Experimental

Authors

  • Sharma, Isha, NORTHWESTERN UNIVERSITY, CHICAGO, Illinois, United States
  • Kanwar, Yashpal S., Northwestern University Medical School, Chicago, Illinois, United States
Background

MIOX, a proximal tubular enzyme, is up-regulated in diabetic state and is involved in the pathogenesis of tubulo-interstitial injury. Previously, we reported that MIOX over-expressing mice with STZ-induced diabetes have remarkable tubulo-interstitial changes. These were largely attributed to excessive generation of ROS leading to increased activity of fibrogenic cytokines, especially in the tubulo-interstitial compartment. Such phenotypic changes were not observed in MIOX-/- mice.

Methods

Aim of this study was to assess if genetic ablation of MIOX ameliorates the progression of tubulo-interstitial injury in ob/ob mice by reducing the oxidant stress in proximal tubules. MIOX-/- mice were cross bred with ob/ob mice to generate mice with double mutation (MIOX-/-/ob/ob). Animals were sacrificed at age of 20 weeks and kidneys were harvested for various studies. Prior to sacrifice blood and urine samples were obtained.

Results

The MIOX-/-/ob/ob mice had improved levels of serum creatinine, urea and insulin compared to ob/ob mice. No change was observed in blood glucose levels. The double mutants had decreased urinary excretion of high molecular weight proteins. The MIOX expression was highly accentuated in kidneys of ob/ob mice compared to WT, and it was absent in MIOX-/- and mice with double mutation. The renal interstitial compartment had notable decreased staining of fibronectin, collagen I and III in mice with double mutation compared to ob/ob mice. The generation of ROS in the kidney tissues was notably less in MIOX-/-/ob/ob mice compared ob/ob mice, as indicated by decreased DHE staining. Analyses of various metabolic sensors revealed revival of the expression of SIRT1, AMPK, YY-1, and of the master regulator of mitochondrial biogenesis, i.e., PGC-1alpha. In vitro, HK-2 cells treated palmitate-BSA had decreased expression of various metabolic sensors with increased ROS generation, and these aberrant parameters of metabolic sensors were normalized with the treatment of MIOX-siRNA.

Conclusion

In conclusion, these findings suggest that ablation of MIOX gene ameliorates the progression of tubulo-interstitial injury in the settings of diabetic nephropathy by reducing the oxidant stress and improving the status of various metabolic sensors.

Funding

  • NIDDK Support