Aldosterone modulates the production of matrix metalloproteinase-2 and -9 via transforming growth factor β1 signaling pathway in podocytes / 中华肾脏病杂志

ABSTRACT

objective To assess the effect of aldosterone on the production of matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9)and collagen Ⅳ in culture supematants of podocytes and the possible molecular mechanisms involved in the influence of aldosterone on the synthesis and degradation of extracellular matrix produced by podocytes. Methods Podecytes were treated with aldosterone at the concentration of 10-11, 10-9, 10-7 mol/L respectively. Cultured podocytes were examined at 24, 48 and 72 hours respectively. Spironolactone, a receptor antagonist of aldosterone, was added to observe the blocking effect on aldosterone. An inhibitor of TGF-β1 receptor was used to determine whether the effect of aldosterone on podocytes were mediated through TGF-β1 system. The enzymatic activities of MMP-2 and MMP-9 were assayed by gehtin zymography. Collagen Ⅳ 0.5 chain and TGF-β1 proteins released into culture supematants were assessed by Western blot and ELISA analysis. The adhesion rate of podocytes was monitored by flow cytometry. Results Aldosterone increased the activities of MMP-2 and MMP-9 in a dose- and time-dependent manner (P<0.05). Aldosterone decreased the level of collagen Ⅳ or5 chain protein in culture supernatants (P<0.05). Meanwhile, the expression of TGF-β1 was also increased (P<0.05). Spironolactone completely abolished the above-mentioned changes(P< 0.05). Blockage of TGF-β1 signaling with SB431542 prevented the aldosterone-induced upregulation of MMP-2 and MMP-9 as well as the downregulation of the collagen Ⅳ α5 chain protein and the adhesion rate of podocytes (P<0.05). Conclusions Aldosterone increases the activities of MMP-2 and MMP-9 but decreases the expression of collagen Ⅳ α5 chain and the adhension rate of podocytes possibly via TGF-β1 signaling pathway. Such alterations may contribute to glomerular podocyte injury associated with the GBM abnormality caused by the imbalance between matrix synthesis and degradation.