Diabetes mellitus increases endothelin-1 gene transcription in rat kidney

Kidney Int. 2000 Oct;58(4):1534-45. doi: 10.1046/j.1523-1755.2000.00315.x.


Background: Mesangial cell hypertrophy and increased extracellular matrix (ECM) contribute to mesangial expansion in early progressive diabetic nephropathy. Previous studies suggest that the growth factor endothelin-1 (ET-1) is not only up-regulated in diabetes, but may mediate the effects of hyperglycemia on mesangial cell hypertrophy and ECM synthesis. In models of diabetes mellitus, the mechanisms underlying increased ET-1 peptide and mRNA remain unknown. Therefore, our purpose is to determine whether ET-1 gene activity increases in kidneys of streptozotocin (SZT)-treated rats.

Methods: Male Sprague-Dawley rats were injected with either SZT or vehicle. Parameters including glucose, body weight, 24-hour urine volume, urinary protein, and urinary ET-1 excretion were recorded. All rats were sacrificed at 12 weeks postinjection. Prepro-ET-1 mRNA from whole kidneys was determined using both RNase protection and reverse transcription-polymerase chain reaction (RT-PCR). The abundance of ET-1 peptide in primary cultured mesangial cells was detected by indirect immunofluorescence following treatment with 5.6, 11.2, or 22.5 mmol/L D-glucose for 24 hours. Cellular ET-1 mRNA was measured using RT-PCR in control cells at time 0 and also following exposure to increasing concentrations of glucose for 24 hours. Rat mesangial cells were transfected with a luciferase reporter construct containing the rat ET-1 promoter (pET1. Luc), and relative ET-1 promoter activity was measured after a 24-hour exposure to 5.6 and 22.5 mmol/L of D- or L-glucose.

Results: After 12 weeks of hyperglycemia, diabetic rats gained less weight (344 +/- 23.9 vs. 548.75 +/- 15.08 g), had increased urinary volume (158.6 +/- 24.32 vs. 8.38 +/- 1.56 mL/day), and had marked proteinuria (101.7 +/- 12.2 vs. 14.1 +/- 2.8 mg/day) compared with controls. Total urinary ET-1 peptide increased 26.4-fold in diabetic versus control rats (17.5083 +/- 5.405 vs. 0.6635 +/- 0.343 ng/day). ET-1 mRNA extracted from whole rat kidneys was increased 2.1-fold in diabetic versus control animals. Primary cultured rat mesangial cells demonstrated a significant increase in immunofluorescence labeling of ET-1 peptide and ET-1 mRNA in response to increasing concentrations of glucose. Furthermore, transfected mesangial cells exposed to 22.5 mmol/L D-glucose showed a 1.6-fold increase in ET-1 promoter activity relative to those treated with 5.6 mmol/L glucose.

Conclusion: Glucose increases ET-1 gene expression in the kidney of the SZT-treated rat model of diabetes mellitus. Furthermore, high glucose induces ET-1 expression in primary cultured rat mesangial cells and directly enhances ET-1 promoter activity. The greater relative increase in peptide compared with transcription suggests the potential participation of other mechanisms such as increased mRNA stability, protein stability, and/or enhanced translational efficiency.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blood Glucose
  • Body Weight
  • Cells, Cultured
  • Diabetes Mellitus, Experimental / physiopathology*
  • Diabetes Mellitus, Experimental / urine
  • Diabetic Nephropathies / physiopathology*
  • Diabetic Nephropathies / urine
  • Endothelin-1 / genetics*
  • Endothelin-1 / urine
  • Endothelins / genetics
  • Extracellular Matrix / physiology
  • Gene Expression / drug effects
  • Gene Expression / physiology
  • Glomerular Mesangium / cytology
  • Glomerular Mesangium / drug effects
  • Glomerular Mesangium / physiology*
  • Glucose / pharmacology
  • Hyperglycemia / physiopathology
  • Hyperglycemia / urine
  • Male
  • Promoter Regions, Genetic / drug effects
  • Promoter Regions, Genetic / physiology
  • Protein Precursors / genetics
  • Proteinuria / physiopathology
  • Proteinuria / urine
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Transcription, Genetic / physiology*
  • Transfection
  • Urine
  • Vasoconstriction / physiology


  • Blood Glucose
  • Endothelin-1
  • Endothelins
  • Protein Precursors
  • RNA, Messenger
  • Glucose