AQP4 KO exacerbating renal dysfunction is mediated by endoplasmic reticulum stress and p66Shc and is attenuated by apocynin and endothelin antagonist CPUO213

Aquaporin 4 (AQP4) is essential in normal kidney. We hypothesized that AQP4 knockout (1(0) may exacerbate pro-inflammatory factors in the stress induced renal insufficiency. Mechanisms underlying are likely due to activating renal oxidative stress adaptor p66Shc and encloplasmic reticulum (ER) stress that could be mediated by enclothelin (ET) NADPH oxidase (NOX) pathway. AQP4 KO and wild type (WT) mice were randomly divided into 4 groups: control, isoproterenol (1 mg/kg, s.c., 5d), and interventions in the last 3 days with either apocynin (NADPH oxidase inhibitor, 100 mg/kg, p.o.) or CPUO213 (a dual enclothelin receptor antagonist 200 mg/kg, p.o.). In addition, HK2 cells were cultured in 4 groups: control, isoproterenol (10(-6) M), intervened with apocynin (10 (3M) or CPUO213 (100(-6)M). In AQP4 KO mice elevated creatinine levels were further increased by isoproterenol compared to AQP4 KO alone. In RT-PCR, western blot and immunohistochemical assay p66Shc and PERK were significantly increased in the kidney of AQP4 KO mice, associated with pro-inflammatory factors CX40, CX43, MMP-9 and ETA compared to the WT mice. Expression of AQP4 was escalated in isoproterenol incubated HK2 cells, and the enhanced protein of PERK and p-PERK/PERK, and p66shc in vivo and in vitro were significantly attenuated by either apocynin or CPUO213. In conclusion, AQP4 KO deteriorates renal dysfunction due to exacerbating ER stress and p66Shc in the kidney. Either endothelia antagonism or NADPH oxiclase blockade partly relieves renal dysfunction through suppressing abnormal biomarkers by APQ4 KO and isoproterenol in ihe kidney. (C) 2013 Elsevier B.V. All rights reserved