Phosphatidylinositol 3-kinase/protein kinase Akt negatively regulates plasminogen activator inhibitor type 1 expression in vascular endothelial cells.
Plasminogen activator inhibitor type 1 (PAI-1) regulates fibrinolytic activity and mediates vascular atherothrombotic disease. Endothelial cells (ECs) synthesize and secrete PAI-1, but the intracellular signaling pathways that regulate PAI-1 expression are not entirely known. We hypothesize that the phosphatidylinositol 3-kinase (PI3K)/protein kinase Akt pathway, which regulates endothelial function, could modulate PAI-1 expression in ECs. Cultured bovine aortic and human saphenous vein ECs were stimulated with TNF-alpha, ANG II, insulin, or serum, and PAI-1 expression was determined by Northern and Western analyses. Inhibition of PI3K with wortmannin or LY-294002 enhanced PAI-1 expression induced by these extracellular stimuli. Similarly, overexpression of a dominant-negative mutant of PI3K or Akt increased TNF-alpha- and insulin-induced PAI-1 expression. The increase in PAI-1 was due to transcriptional and posttranscriptional mechanisms as PI3K inhibitors increased PAI-1 promoter activity and mRNA stability. The induction of PAI-1 by TNF-alpha and insulin is mediated, in part, by ERK and p38 MAPK. PI3K inhibitors augmented TNF-alpha- and insulin-induced phosphorylation of these MAPKs. Simvastatin, a 3-hydroxy-3-methylglutaryl-CoA reductase inhibitor, which is known to activate PI3K/Akt, blocks TNF-alpha- and insulin-induced PAI-1 expression. Treatment with PI3K inhibitors reversed the inhibitor effects of simvastatin on TNF-alpha- and insulin-induced PAI-1 expression. These findings indicate that the PI3K/Akt pathway acts as a negative regulator of PAI-1 expression in ECs, in part, through the downregulation of MAPK pathways. These results suggest that factors that activate the PI3K/Akt pathway in ECs may have therapeutic benefits for atherothrombotic vascular disease.
Mukai
Yasushi
Y
Vascular Medicine Research Unit, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02139, USA.
Wang
Chao-Yung
CY
Rikitake
Yoshiyuki
Y
Liao
James K
JK
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000166:cytology; D002417:Cattle; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism; D002867:Chromones / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology*; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics* / Q000378:metabolism; D012501:Saphenous Vein / Q000166:cytology; D015398:Signal Transduction / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014471:Umbilical Veins / Q000166:cytology; D000077191:Wortmannin
D000730:Androstadienes; D002784:Cholesterol; D002867:Chromones; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017395:Plasminogen Activator Inhibitor 1; D047428:Protein Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D014409:Tumor Necrosis Factor-alpha; D000077191:Wortmannin; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one