Effect of TGF-a1 on plasminogen activator inhibitor-1 expression in rat glomerular mesangial cells

Objective To investigate TGF-a1 regulating PAI-1 expression i n glomerular mesangial cells and to examine the role of reactive oxygen species(RO S) in signaling pathway of TGF-a1-induced PAI-1 expression. Methods Growth a rrested and synchronized rat mesangial cells were stimulated by TGF-a1(2 ng/m l)or glucose oxidase(GO)(10 mU/ml),respectively.The mesangial cells were pret reated with DL-bathionine-(S,R)-sulfoximine(BSO) or with antioxidant N-acet ylcysteine(NAC). PAI-1 protein secretion by mesangial cells was measured by Wes tern blot and PAI-1 mRNA by both RT-PCR and Northern blot. Plasmin activity wa s determined by using a synthetic fluorometric plasmin substrate. Results Exogen ous TGF-a1 and GO significantly upregulated PAI-1 mRNA and protein expression in mesangial cells and reduced the activity of plasmin. TGF-a1-and GO-induc ed upregulation of PAI-1 mRNA and protein expression was exaggerated by BSO.NAC effectively reversed TGF-a1-and GO-induced PAI-1 mRNA and protein overexpr ession. Conclusions TGF-a1 significantly upregulates the PAI-1 expression in mesangial cells and reduces the activity of plasmin. ROS acts as a mediator in s ignaling pathway of TGF-a1-induced PAI-1 overexpression.