Podocyte-Specific GLUT4-Deficient Mice Have Fewer and Larger Podocytes and Are Protected From Diabetic Nephropathy

  1. Alessia Fornoni1,2
  1. 1Diabetes Research Institute, Miller School of Medicine, University of Miami, Miami, FL
  2. 2Department of Medicine, Division of Nephrology and Hypertension, Miller School of Medicine, University of Miami, Miami, FL
  3. 3Department of Physiology, Miller School of Medicine, University of Miami, Miami, FL
  4. 4Department of Surgery, Miller School of Medicine, University of Miami, Miami, FL
  5. 5Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
  6. 6Division of Nephrology, Freiburg University, Freiburg, Germany
  7. 7Division of Nephrology, University of Michigan, Ann Arbor, MI
  8. 8Division of Endocrinology, Metabolism and Diabetes and Program in Molecular Medicine, University of Utah, Salt Lake City, UT
  1. Corresponding author: Alessia Fornoni, afornoni{at}med.miami.edu.

Abstract

Podocytes are a major component of the glomerular filtration barrier, and their ability to sense insulin is essential to prevent proteinuria. Here we identify the insulin downstream effector GLUT4 as a key modulator of podocyte function in diabetic nephropathy (DN). Mice with a podocyte-specific deletion of GLUT4 (G4 KO) did not develop albuminuria despite having larger and fewer podocytes than wild-type (WT) mice. Glomeruli from G4 KO mice were protected from diabetes-induced hypertrophy, mesangial expansion, and albuminuria and failed to activate the mammalian target of rapamycin (mTOR) pathway. In order to investigate whether the protection observed in G4 KO mice was due to the failure to activate mTOR, we used three independent in vivo experiments. G4 KO mice did not develop lipopolysaccharide-induced albuminuria, which requires mTOR activation. On the contrary, G4 KO mice as well as WT mice treated with the mTOR inhibitor rapamycin developed worse adriamycin-induced nephropathy than WT mice, consistent with the fact that adriamycin toxicity is augmented by mTOR inhibition. In summary, GLUT4 deficiency in podocytes affects podocyte nutrient sensing, results in fewer and larger cells, and protects mice from the development of DN. This is the first evidence that podocyte hypertrophy concomitant with podocytopenia may be associated with protection from proteinuria.

Footnotes

  • Received May 8, 2013.
  • Accepted October 2, 2013.

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  1. Diabetes vol. 63 no. 2 701-714
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