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Renoprotective role of the vitamin D receptor in diabetic nephropathy

Z Zhang1, L Sun, Y Wang

  • 1Division of Biological Sciences, Department of Medicine, The University of Chicago, Chicago, Illinois, USA.

Kidney International
|October 12, 2007
PubMed

Insights

Vitamin D receptor (VDR) deficiency worsens diabetic kidney disease. VDR activation protects against kidney injury by regulating the renin-angiotensin system (RAS) and reducing inflammation.

Area of Science:

  • Endocrinology
  • Nephrology
  • Molecular Biology

Background:

  • Diabetic nephropathy is a major complication of diabetes.
  • The renin-angiotensin system (RAS) is implicated in diabetic kidney disease progression.
  • Vitamin D plays a role in regulating the RAS.

Purpose of the Study:

  • To investigate the role of the vitamin D receptor (VDR) in diabetic nephropathy.
  • To determine if VDR deficiency exacerbates hyperglycemia-induced renal injury.

Main Methods:

  • Utilized VDR knockout mice and wild-type mice subjected to diabetic conditions.
  • Assessed renal injury markers including albuminuria, glomerulosclerosis, and podocyte morphology.
  • Quantified expression of fibronectin (FN), nephrin, and components of the RAS and TGF-beta signaling pathways.
  • Examined the effects of 1,25-dihydroxyvitamin D3 on high glucose-induced changes in cultured mesangial and podocyte cells.

Main Results:

  • Diabetic VDR knockout mice exhibited more severe albuminuria and glomerulosclerosis than diabetic wild-type mice.
  • VDR knockout mice showed increased glomerular basement membrane thickening, podocyte effacement, higher fibronectin, and lower nephrin expression.
  • Elevated renin, angiotensinogen, transforming growth factor-beta (TGF-beta), and connective tissue growth factor were observed in VDR knockout mice.
  • 1,25-dihydroxyvitamin D3 inhibited high glucose-induced fibronectin production and increased nephrin expression in vitro.
  • Vitamin D suppressed high glucose-induced activation of the RAS and TGF-beta signaling in renal cells.

Conclusions:

  • Vitamin D receptor-mediated actions are renoprotective in the context of diabetic nephropathy.
  • VDR deficiency exacerbates renal injury in diabetes, partly through dysregulation of the RAS and TGF-beta pathways.
  • Targeting the VDR may offer a therapeutic strategy for managing diabetic kidney disease.

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