Overexpression of GFAT activates PAI-1 promoter in mesangial cells

Leighton R James, I. George Fantus, Howard Goldberg, Hao Ly, James W. Scholey

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

Effects of hyperglycemia on glomerular cells may be mediated by glucose entry into the hexosamine pathway, and mesangial cell (MC) expression of the hexosamine pathway rate-limiting enzyme glutamine:fructose-6-phosphate amido-transferase (GFAT) is increased in diabetic glomerulosclerosis. We hypothesized that GFAT activity would be an important determinant of gene expression in glomerular MC. When overexpressed in primary MC, GFAT produced a two- to threefold increase in the activity of plasminogen activator inhibitor-1 (PAI-1) promoter. There was a 1.4-fold increase in PAI-1 promoter activity in cells exposed to high glucose (20 mM), whereas in MC overexpressing GFAT, exposure to high glucose caused a 3.5- to 4-fold increase in promoter activity. PAI-1 promoter activation was dependent on GFAT enzyme activity because o-diazo-acetyly-L-serine and 6-diazo-5-oxonorleucine, inhibitors of GFAT enzyme activity, abrogated the activation of PAI-1 promoter in MC overexpressing GFAT. Glucosamine, which is downstream of GFAT in the hexosamine pathway, produced a 2.5-fold increase in the PAI-1 promoter activity. In addition to increasing the mRNA levels for transforming growth factor-β1 (TGF-β1), GFAT overexpression also increased mRNA levels for the TGF-β type I and type II receptors. TGF-β-neutralizing antibody did not normalize PAI-1 promoter activity in MC exposed to glucosamine or those overexpressing GFAT. We conclude that GFAT expression and activity are important determinants of gene expression in MC and that flux through the hexosamine pathway activates expression of genes implicated in vascular injury pathways.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Renal Physiology
Volume279
Issue number4 48-4
StatePublished - Dec 7 2000
Externally publishedYes

Fingerprint

Mesangial Cells
Plasminogen Activator Inhibitor 1
Transferases
Glutamine
Hexosamines
Glucosamine
Gene Expression
Glucose
fructose-6-phosphate
Enzymes
Messenger RNA
Vascular System Injuries
Diabetic Nephropathies
Transforming Growth Factors
Neutralizing Antibodies
Hyperglycemia
Serine

Keywords

  • Diabetic nephropathy
  • Gene expression
  • Glutamine:fructose-6-phosphate amidotransferase
  • Plasminogen activator inhibitor-1

ASJC Scopus subject areas

  • Physiology
  • Urology

Cite this

Overexpression of GFAT activates PAI-1 promoter in mesangial cells. / James, Leighton R; Fantus, I. George; Goldberg, Howard; Ly, Hao; Scholey, James W.

In: American Journal of Physiology - Renal Physiology, Vol. 279, No. 4 48-4, 07.12.2000.

Research output: Contribution to journalArticle

James, Leighton R ; Fantus, I. George ; Goldberg, Howard ; Ly, Hao ; Scholey, James W. / Overexpression of GFAT activates PAI-1 promoter in mesangial cells. In: American Journal of Physiology - Renal Physiology. 2000 ; Vol. 279, No. 4 48-4.
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