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Abstract: FR-PO409

ENaC and MARCKS Proteolysis in Diabetes Associated Hypertension

Session Information

Category: Diabetic Kidney Disease

  • 601 Diabetic Kidney Disease: Basic

Authors

  • Tuna, Kubra M., University of Florida, Gainesville, Florida, United States
  • Ghazi, Zinah M., Emory University, Atlanta, Georgia, United States
  • Yue, Qiang, Emory University, Atlanta, Georgia, United States
  • Eaton, Douglas C., Emory University Medical School, Atlanta, Georgia, United States
  • Alli, Abdel A., University of Florida, Gainesville, Florida, United States
Background

The majority of T2DM patients present with hypertension and diabetic nephropathy progresses more rapidly in hypertensive diabetic patients compared to those without hypertension. Thus, there is an urgent need to better understand the mechanisms contributing to diabetes associated hypertension in order to reduce morbidity and mortality in these patients. Proteolysis of both the epithelial sodium channel (ENaC) and the myristoylated alanine-rich C-kinase substrate (MARCKS) is necessary for high levels of ENaC activity.

Methods

Here we use salt-loaded db/db mice and control mice to test the hypothesis that increased proteolysis of ENaC and MARCKS plays an essential role in the pathogenesis of hypertension secondary to diabetes. Cleaved ENaC and MARCKS was assessed by Western blotting. Protease activity was measured by zymography and fluorometric assays. ENaC activity was assessed by electrophysiology. Blood pressure was measured by telemetry.

Results

Western blots using validated antibodies showed both ENaC and MARCKS proteolysis is increased in the diabetic db/db kidneys compared to kidneys from C57B6 wild-type mice. Western blot and zymography analyses showed increased expression and activity of proteases including cathepsins in the diabetic db/db kidneys compared to controls. ENaC activity was increased in split-open tubules from salt-loaded diabetic db/db mice compared to controls. Telemetry studies showed mean arterial pressure was increased in these diabetic db/db mice after salt-loading and the blood pressure was restored by daily injections with amiloride.

Conclusion

This project will contribute to our understanding of the protease-dependent regulation of ENaC and MARCKS in the development of diabetes associated hypertension and potentially lead to novel drug targets and therapeutics.

Funding

  • NIDDK Support