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Abstract: SA-OR025

Mice with Drp1-S600 Knockin Mutation Exhibit Reduced Mitochondrial Fission and Attenuation of Diabetic Nephropathy

Session Information

Category: Diabetic Kidney Disease

  • 601 Diabetic Kidney Disease: Basic

Authors

  • Galvan, Daniel L., University of Texas MD Anderson Cancer Center , Houston, Texas, United States
  • Long, Jianyin, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States
  • Green, Nathanael, Baylor College of Medicine, Houston, Texas, United States
  • Lin, Jamie, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States
  • Chang, Benny B., Baylor College of Medicine, Houston, Texas, United States
  • Danesh, Farhad R., UT MD Anderson, Houston, Texas, United States
Background

Mitochondrial fission has been linked to the pathogenesis of diabetic nephropathy (DN), but how this process affects progression of DN in vivo remains elusive. We have previously reported the role Dynamin-related protein1 (Drp1), a key component of mitochondrial fission, and its phosphorylation at serine 600 on mitochondrial dynamics in podocytes in vitro. We now report the in vivo consequences of S600 phosphorylation in progression of DN in a mouse model of Type 2 diabetes.

Methods

We generated a S600 phospho-dead Drp1 knockin mouse on the C57BL/6 background via point mutation of serine 600 to alanine. Following C57Bl6/J ES cell electroporation, selection, and screening of colonies by southern blot and PCR analysis, we identified several positive clones and generated chimeric S600A mice. We next generated heterozygous S600+/A and homozygous S600A/A mice. We crossed the Drp1-S600 mice with Leprdb/+ mice, a well-established model of Type 2 diabetes, to generate homozygous diabetic Drp1-S600A/A mice (Leprdb/db; Drp1-S600A/A).

Results

Diabetic Drp1-S600 mutant mice were followed over the course of 16 weeks. Diabetic mice did not exhibit any differences in their body weight or blood glucose levels. In contrast, as compared to diabetic wild-type, both hetero- and homozygous diabetic Drp1-S600A mice exhibited significantly reduced albuminuria. Histological analysis by Periodic-Schiff’s Acid (PAS) stain and quantification of glomerular area positive for PAS stain, revealed attenuated mesangial matrix expansion in glomeruli of db/db;Drp1-S600A/+;A/A compared to controls. Transmission electron micrographs (TEM) also revealed reduced podocyte foot process effacement and reduced glomerular basement membrane thickening in diabetic Drp1-S600A/+;A/A compared to diabetic controls. TEM of podocytes also revealed elongated mitochondria and increased aspect ratio in mitochondria from db/db;Drp1-S600A mice compared to wild-type diabetic mice. Our results are consistent with preservation of mitochondrial morphology and structure in S600 mutant mice.

Conclusion

These findings demonstrate that a single phosphorylation site in Drp1 regulate mitochondrial fission and progression of DN and elucidate a potential role for targeting Drp1-S600 phosphorylation in DN.

Funding

  • NIDDK Support