The hexosamine pathway regulates the plasminogen activator inhibitor-1 gene promoter and Sp1 transcriptional activation through protein kinase C-beta I and -delta.
Increased flux through the hexosamine biosynthesis pathway (HBP) has been shown to stimulate the expression of a number of genes. We previously demonstrated in glomerular mesangial and endothelial cells that both high glucose concentrations and glucosamine activated the plasminogen activator inhibitor-1 (PAI-1) gene promoter through the transcription factor, Sp1; and that the glutamine:fructose-6-phosphate amidotransferase inhibitor, 6-diazo-5-oxonorleucine, inhibited the effect of high glucose, but not that of glucosamine. Here, we examined the role of protein kinase C (PKC) isoforms in the regulation of the PAI-1 promoter and Sp1 transcriptional activity by the HBP. In transient transfections, exposure to 2 mm glucosamine or 20 mm glucose for 4 days increased the activities of a PAI-1 promoter-luciferase reporter gene as well as the Sp1 transcriptional activation domain fused to the GAL4 DNA-binding domain cotransfected with a GAL4 promoter-luciferase reporter. Cotransfected dominant negative PKC-betaI and -delta completely blocked the induction of PAI-1 promoter transcription by both sugars, whereas only dominant negative PKC-betaI interfered with Sp1-GAL4 activation. Both glucosamine and high glucose stimulated the in vitro kinase activity of immunoprecipitated PKC-betaI and -delta. Furthermore, 6-diazo-5-oxonorleucine suppressed high glucose-induced PKC kinase activity and Sp1-GAL4 transcriptional activation. These findings demonstrate a requirement for the PKC-betaI and -delta signal transduction pathways in HBP-induced transcription.
Goldberg
Howard J
HJ
Department of Medicine, Mount Sinai Hospital and University Health Network, 600 University Avenue, Suite 780, Toronto, Ontario M5G 1X5, Canada.
Whiteside
Catharine I
CI
Fantus
I George
IG
D000818:Animals; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D005920:Glomerular Mesangium / Q000201:enzymology; D005944:Glucosamine / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D006031:Glycosylation; D006595:Hexosamines / Q000096:biosynthesis*; D007527:Isoenzymes / Q000502:physiology*; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics*; D011401:Promoter Regions, Genetic; D011493:Protein Kinase C / Q000502:physiology*; D064546:Protein Kinase C beta; D051745:Protein Kinase C-delta; D051381:Rats; D016329:Sp1 Transcription Factor / Q000235:genetics*; D015533:Transcriptional Activation
D006595:Hexosamines; D007527:Isoenzymes; D017395:Plasminogen Activator Inhibitor 1; D016329:Sp1 Transcription Factor; C497260:Prkcd protein, rat; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D051745:Protein Kinase C-delta; D005947:Glucose; D005944:Glucosamine