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Abstract: FR-PO217

Endothelial Nitric Oxide and the Podocyte NFAT2/Heparanase Axis in Diabetic Nephropathy

Session Information

Category: Diabetic Kidney Disease

  • 601 Diabetic Kidney Disease: Basic

Authors

  • Katagiri, Daisuke, National Center for Global Health and Medicine, Tokyo, Tokyo, Japan
  • Nagasaka, Shinya, Nippon Medical School, Tokyo, Japan
  • Takahashi, Keiko, Vanderbilt University Medical Center, Nashville, Tennessee, United States
  • Wang, Suwan, Vanderbilt University Medical Center, Nashville, Tennessee, United States
  • Zhang, Ming-Zhi, Vanderbilt University Medical Center, Nashville, Tennessee, United States
  • Shimizu, Akira, Nippon Medical School, Tokyo, Japan
  • Harris, Raymond C., Vanderbilt University Medical Center, Nashville, Tennessee, United States
  • Takahashi, Takamune, Vanderbilt University Medical Center, Nashville, Tennessee, United States
Background

A reduction in endothelial nitric oxide synthase (eNOS) activity serves as a key driver in the development and progression of diabetic nephropathy (DN), which has been studied using global eNOS knockout (eNOSGKO) mice for a decade. However, eNOSGKO mice have several inherent problems including a tendency to develop progressive renal disease regardless of diabetic status. Diabetic eNOSGKO mice exhibit advanced podocytopathy, but the detailed mechanism is unknown. The calcineurin-nuclear factor of activated T cells (NFAT) signaling pathway has been reported to cause podocyte injury.

Methods

To determine the precise role of eNOS in DN, we created floxed eNOS mice. We conditionally deleted endothelial cell-specific eNOS expression (E-eNOSKO) after the onset of diabetes in mice to more closely represent the clinical course of human DN. Streptozotocin was used to generate diabetes. Tamoxifen was used to conditionally knock out endothelial cell-specific eNOS. To evaluate the role of NFAT2 in podocyte injury in diabetic eNOSKO mice, Podocin-Cre NFAT2 floxed eNOSGKO mice were also generated. A cyclin-dependent kinase 4-transformed podocyte line was treated with an NO donor in high glucose conditions.

Results

Diabetic E-eNOSKO mice showed significantly increased albuminuria with progressive glomerular lesion changes. We evaluated NFAT isoforms and found that NFAT2 was upregulated in podocytes in advanced DN patients and diabetic E-eNOSKO mice. NFAT2 activation in cultured podocytes was upregulated by high glucose and suppressed by NO donor treatment in a dose-dependent manner. Heparanase (HPSE), the only mammalian endoglycosidase that degrades heparan sulfate, was expressed in podocytes in both advanced DN patients and our model. HPSE was upregulated in cultured podocytes under high glucose conditions and was suppressed by NO donor treatment. Transfection of constitutively active NFAT2 increased HPSE in cultured podocytes. Podocyte-specific NFAT2-deleted diabetic eNOSGKO mice showed attenuated albuminuria with decreased HPSE expression in podocytes.

Conclusion

Our findings indicate that eNOS has a crucial role in the regulation of HPSE in podocytes through NFAT2 activation, which suppresses proteinuria in advanced DN.

Funding

  • Government Support - Non-U.S.