NHERF1 loss results in metabolic stress and increased susceptibility to cisplatin‐induced acute kidney injury

Abstract

BackgroundAcute kidney injury (AKI) is associated with a high mortality rate and develops in 30% of patients who receive cisplatin. The sodium hydrogen regulatory factor isoform 1 (NHERF1) is a scaffolding protein that anchors multiple membrane proteins, in renal proximal tubules. We have recently demonstrated that NHERF1 loss results in changes in mitochondrial protein abundance and function.HypothesisWe hypothesize that NHERF1 loss increases susceptibility to AKI through an underlying metabolic stress.Materials and MethodsWe treated 2 month old male and female wild type (WT) C57BL/6 and NHERF1 knock out (KO) mice with vehicle (VEH) or cisplatin (CIS) (20 mg/kg dose IP) and euthanized after 72 hours. Blood was collected for blood urea nitrogen (BUN) levels. Urine was collected for NGAL. Kidneys were harvested for histology, TUNEL assay, and Western Blot for cleaved caspase 3. Proteomic analysis was conducted on kidney brush border membrane (BBM) of WT and KO kidneys. Metabolic measurements were conducted via the XF Flux analyzer on non‐treated primary proximal tubule cell cultures. Three‐way ANOVA was used to compare the different treatment groups. Ordinal regression was performed for the semi‐quantitative scoring. All statistical analysis was conducted with SPSS software. P values of <0.05 were considered statistically significant.ResultsCIS caused significantly greater severity of kidney injury in KO compared to WT mice by semi‐quantitative injury score (WT: 1.89, KO: 2.8), BUN levels (WT: 97.8 mg/dL +/− 10.1, KO: 151.8 mg/dL +/− 17.2) and NGAL protein (WT: 2.7 μg/mL +/− 0.53, KO: 55.6 μg/mL +/−21.3). Apoptosis markers were significantly increased in CIS treated KO and WT mice compared to respective controls. Proteomic comparison of BBM protein expression in WT and KO showed marked changes in the expression of mitochondrial proteins in KO mice, suggesting alterations in cell metabolism. KO proximal tubule cells also exhibited decreases of 35% in glycolytic reserve capacity, 40% in baseline mitochondrial respiration rate, 37% in ATP‐linked mitochondrial respiration rate, 40% in mitochondrial reserve capacity, and 40% in maximum mitochondrial capacity.ConclusionsWe conclude that the KO mice have increased susceptibility to CIS‐induced AKI, which may be due to altered metabolism and/or mitochondrial dysfunction.Support or Funding InformationFunding for this research was provided by VA and UofL School of Medicine (to EDL).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.