Cell stress response impairs de novo NAD+ biosynthesis in the kidney
Yohan Bignon, Anna Rinaldi, Zahia Nadour, Virginie Poindessous, Ivan Nemazanyy, Olivia Lenoir, Baptiste Fohlen, Pierre Weill-Raynal, Alexandre Hertig, Alexandre Karras, Pierre Galichon, Maarten Naesens, Dany Anglicheau, Pietro E. Cippà, Nicolas Pallet
Yohan Bignon, Anna Rinaldi, Zahia Nadour, Virginie Poindessous, Ivan Nemazanyy, Olivia Lenoir, Baptiste Fohlen, Pierre Weill-Raynal, Alexandre Hertig, Alexandre Karras, Pierre Galichon, Maarten Naesens, Dany Anglicheau, Pietro E. Cippà, Nicolas Pallet
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Research Article Metabolism Nephrology

Cell stress response impairs de novo NAD+ biosynthesis in the kidney

Abstract

The biosynthetic routes leading to de novo nicotinamide adenine dinucleotide (NAD+) production are involved in acute kidney injury (AKI), with a critical role for quinolinate phosphoribosyl transferase (QPRT), a bottleneck enzyme of de novo NAD+ biosynthesis. The molecular mechanisms determining reduced QPRT in AKI, and the role of impaired NAD+ biosynthesis in the progression to chronic kidney disease (CKD), are unknown. We demonstrate that a high urinary quinolinate-to-tryptophan ratio, an indirect indicator of impaired QPRT activity and reduced de novo NAD+ biosynthesis in the kidney, is a clinically applicable early marker of AKI after cardiac surgery and is predictive of progression to CKD in kidney transplant recipients. We also provide evidence that the endoplasmic reticulum (ER) stress response may impair de novo NAD+ biosynthesis by repressing QPRT transcription. In conclusion, NAD+ biosynthesis impairment is an early event in AKI embedded with the ER stress response, and persistent reduction of QPRT expression is associated with AKI to CKD progression. This finding may lead to identification of noninvasive metabolic biomarkers of kidney injury with prognostic and therapeutic implications.

Authors

Yohan Bignon, Anna Rinaldi, Zahia Nadour, Virginie Poindessous, Ivan Nemazanyy, Olivia Lenoir, Baptiste Fohlen, Pierre Weill-Raynal, Alexandre Hertig, Alexandre Karras, Pierre Galichon, Maarten Naesens, Dany Anglicheau, Pietro E. Cippà, Nicolas Pallet

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Figure 3

ER stress reduces de novo NAD+ biosynthesis in the kidney.

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ER stress reduces de novo NAD+ biosynthesis in the kidney. (A) Qprt gene...
(A) Qprt gene expression in the renal cell types identified by snRNA-Seq of 8 control kidney samples (25,896 cells). (B) Representative photomicrograph of human QPRT expression evaluated by immunohistochemistry in kidney. Original magnification, ×40. (C) Hierarchical clustering of HK2 cells incubated with 2.5 μg/mL of Tun or DMSO or vehicle for 4 hours and 8 hours (4 replicates). (D) Volcano plot comparing urinary metabolites of HK2 cells incubated with or without 2.5 μg/mL Tun for 8 hours. (E) Concentrations of total NAD concentrations, NAD+, and NADH, in HK2 cells incubated with 2.5 μg/mL Tun or 5 μg/mL BFA or DMSO for 24 hours (4–5 replicates). Bars represent mean ± SEM. P value was computed with Dunnett’s multiple-comparison test. (F) Concentrations of total NAD concentrations, NAD+, and NADH, in HK2 cells incubated with 2.5 μg/mL Tun alone with or without 100 μmol/L of TES1025 for 24 hours (n = 3–4 replicates). Bars represent mean ± SEM. P value was computed with Dunnett’s multiple-comparison test. (G) Immunoblot representing PARP, its cleaved fragment, and binding immunoglobulin protein (BiP) expression in HK2 cells 24 hours after incubation with DMSO, 2.5 μg/mL Tun, 5 μg/mL BFA, or 100 μM etoposide (Eto). The immunoblot shown is representative of 3 independent experiments. (H) Relative expression of QPRT measured by real-time quantitative polymerase chain reaction (RT-qPCR) in HK2 cells incubated with 2.5 μg/mL Tun, 5 μg/mL BFA, and 100 μM Eto or DMSO for 24 hours (3 replicates per condition). Bars represent mean ± SEM. (I) The PARylation activity of PARP in HK2 cells incubated with DMSO, 2.5 μg/mL Tun, 5 μg/mL BFA, or 100 μM Eto (3–4 replicates). Bars represent mean ± SEM. (J) Relative expression of CD38 measured by RT-qPCR in HK2 cells incubated with 2.5 μg/mL Tun or 5 μg/mL of BFA or DMSO for 24 hours (3–4 replicates per condition). Bars represent mean ± SEM. P value was computed with 1-way ANOVA.