Aims: To investigate the effects of urokinase-type plasminogen activator (uPA) on proliferation and phenotypic transformation of rat mesangial cells (MCs) under high glucose conditions and its possible signal transduction pathway.
Methods: Rat MC were divided into 4 groups: the control group, the high glucose group, the high glucose and wortmannin group, and the high glucose and uPA group. MC proliferation in all groups was detected by the 3-(4,5-dimethylthiazol-)-2,5-diphenyltetrazolium bromide (MTT) method. MC cell cycle was analyzed by flow cytometry. Expression of cyclin dependent kinase 2 (CDK2), and activity of the signaling protein Akt in MC were detected by Western blot. Expression pattern and quantity of α-smooth muscle actin (α-SMA) in MC were examined using laser confocal microscopy. The expression of plasminogen activator inhibitor-1 (PAI-1), and collagen IV in renal tissues in rats was tested with immunohistochemistry and Western blotting methods.
Results: Activation of Akt induced by high glucose can be reduced significantly by wortmannin and uPA. There was no obvious change in CDK2 protein expression in different groups (P>0.05). Expression of α-SMA in MC cytoplasm increased dramatically (P<0.01). Expression of α-SMA decreased significantly in the high glucose and wortmannin group and the high glucose and uPA group compared with that of the high glucose group (P<0.01). In diabetic rats, uPA down-regulated PAI-1 and collagen IV expression in mesangial matrix (P<0.05).
Conclusion: uPA antagonizes cell proliferation and phenotypic transformation of MCs induced by high glucose through inhibiting Akt signaling pathway.
Keywords: Mesangial cells (MC) proliferation; Signal transduction; Urokinase-type plasminogen activator (uPA).
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