Mitochondrial derived reactive oxygen species mediates aldosterone-induced epidermal growth factor receptor activation and mesangial cell proliferation / 中华肾脏病杂志

ABSTRACT

Objective To detect the signaling pathways involved in aldosterone (ALDO)induced mesangial cell (MC) proliferation. Methods The incorporation of 3H-thymidine (3H-TdR)and cell count were used as the measure of mesangial cell (MC) proliferation. Reactive oxygen species (ROS) production was determined by DCFDA fluorescence. Epidermal growth factor receptor (EGFR) activation was assayed by Western blotting. Results ALDO induced MC proliferation.When incubation with 100 nmol/L ALDO for 24 h, the 3H-TdR incorporation and cell number increased by 2.63- and 2.15-fold, respectively. Mineralocorticoid receptor (MR) antagonist EPLE almost completely blocked ALDO-induced MC proliferation (P<0.01), however, glucocorticoid receptor (GR) antagonist RU-486 had no effect on MC proliferation. ALDO increased intracellular ROS production in cultured human MCs. When incubation with ALDO (100 nmol/L) for 60 min,ROS production increased by 2.14-fold. ALDO-induced ROS generation was completely blocked by EPLE as well as mitochondrial complex Ⅰ inhibitor rotenone (P<0.01=, NADPH oxidase inhibitors diphenyleneiodonium sulfate (DPI) and apocynin inhibited ALDO-induced ROS production by 30%to 35% (P<0.05=. In contrast, inhibitors of other oxidant-producing enzymes, including allopurinol,indomethacin, nordihydroguiaretic acid, ketoconazole and G-nitro-L-arginine methyl ester (L-NAME)had no effect on ALDO-induced ROS production. Antioxidant N-acetyl-L-cysteine (NAC) and ROT inhibited ALDO-induced MC proliferation by 75% to 80%, whereas the inhibition of NADPH oxidase inhibitor apocynin and DPI on ALDO-induced MC proliferation was 25% to 30%. ALDO induced EGFR transactivation. When incubation with 100 nmol/L ALDO for 60 min, EGFR phosphorylation was increased by 4.95-fold, which was completely inhibited by EPLE and antioxidant NAC (P<0.01=. NAC and EGFR antagonist AG1478 significantly blocked ALDO-induced MC proliferation (P<0.01=. Conclusions ALDO-induced MC proliferation is mediated by ROS-dependent EGFR transactivation. ALDO-stimulated ROS is mainly generated by mitochondria.