NHERF1 Loss Upregulates Enzymes of the Pentose Phosphate Pathway in Kidney Cortex.

Adrienne Bushau-Sprinkle,Michelle T Barati,Barbara Clark,Kathleen Kitterman,Eleanor Lederer,Syed Jalal Khundmiri,Kenneth B Gagnon,Michael Brier,Shesh N Rai,Sudhir Srivastava,Jessica Hata,Amanda Sherwood,Bradford G Hill,Leah Siskind,Michael Merchant

doi:10.3390/antiox9090862

Abstract

(1) Background: We previously showed Na/H exchange regulatory factor 1 (NHERF1) loss resulted in increased susceptibility to cisplatin nephrotoxicity. NHERF1-deficient cultured proximal tubule cells and proximal tubules from NHERF1 knockout (KO) mice exhibit altered mitochondrial protein expression and poor survival. We hypothesized that NHERF1 loss results in changes in metabolic pathways and/or mitochondrial dysfunction, leading to increased sensitivity to cisplatin nephrotoxicity. (2) Methods: Two to 4-month-old male wildtype (WT) and KO mice were treated with vehicle or cisplatin (20 mg/kg dose IP). After 72 h, kidney cortex homogenates were utilized for metabolic enzyme activities. Non-treated kidneys were used to isolate mitochondria for mitochondrial respiration via the Seahorse XF24 analyzer. Non-treated kidneys were also used for LC-MS analysis to evaluate kidney ATP abundance, and electron microscopy (EM) was utilized to evaluate mitochondrial morphology and number. (3) Results: KO mouse kidneys exhibit significant increases in malic enzyme and glucose-6 phosphate dehydrogenase activity under baseline conditions but in no other gluconeogenic or glycolytic enzymes. NHERF1 loss does not decrease kidney ATP content. Mitochondrial morphology, number, and area appeared normal. Isolated mitochondria function was similar between WT and KO. Conclusions: KO kidneys experience a shift in metabolism to the pentose phosphate pathway, which may sensitize them to the oxidative stress imposed by cisplatin.

Highlights

Cisplatin is a widely used chemotherapeutic that treats a variety of solid malignant tumors, its nephrotoxicity limits its use [1]
brush border membrane (BBM) were prepared from the kidney cortex of WT and Na/H exchange regulatory factor 1 (NHERF1) KO mice, followed by comparative proteomic analysis
Pathway analysis of differentially expressed proteins revealed significant changes in proteins associated with mitochondrial function as well as protein components of signaling pathways, actin cytoskeleton, cell survival, and oxidative phosphorylation (Supplementary Materials Figure S1, Table S1)

Summary

Introduction

Cisplatin is a widely used chemotherapeutic that treats a variety of solid malignant tumors (e.g., ovarian testicular, head and neck, and lung cancer), its nephrotoxicity limits its use [1]. The accumulation and bioactivation of cisplatin to a more nephrotoxic metabolite underlies the kidney’s susceptibility to cisplatin-induced AKI. Cisplatin has been found to accumulate in the mitochondria of renal epithelial cells [10,11], resulting in mitochondrial damage including decreased mitochondrial mass, disruption of cristae, and even mitochondrial swelling [12,13,14]. These morphological changes are associated with a significant reduction in mitochondrial activity and ATP production [12,13]

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