Perturbations of NAD+ salvage systems impact mitochondrial function and energy homeostasis in mouse myoblasts and intact skeletal muscle

Marianne Agerholm Andersen, Morten Dall, Benjamin Anderschou Holbech Jensen, Clara Prats, Søren Madsen, Astrid Linde Basse, Anne-Sofie Graae, Steve Risis, Julie Goldenbaum, Bjørn Quistorff, Steen Larsen, Sara Gry Vienberg, Jonas Thue Treebak

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

34 Citationer (Scopus)

Abstract

Nicotinamide adenine dinucleotide (NAD+) can be synthesized by nicotinamide phosphoribosyltransferase (NAMPT). We aimed to determine the role of NAMPT for maintaining NAD+ levels, mitochondrial function, and metabolic homeostasis in skeletal muscle cells. We generated stable Nampt knockdown (shNampt KD) C2C12 cells using a shRNA lentiviral approach. Moreover, we applied gene electrotransfer to express cre recombinase in tibialis anterior muscle of floxed Nampt mice. In shNampt KD C2C12 myoblasts, Nampt and NAD+ levels were reduced by 70% and 50%, respectively, and maximal respiratory capacity was reduced by 25%. Moreover, anaerobic glycolytic flux increased by 55% and 2-deoxyglucose uptake increased by 25% in shNampt KD cells. Treatment with the NAD+ precursor nicotinamide riboside restored NAD+ levels in shNampt cells and increased maximal respiratory capacity by 18% and 32% in control and shNampt KD cells, respectively. Expression of cre recombinase in muscle of floxed Nampt mice reduced NAMPT and NAD+ levels by 38% and 43%, respectively. Glucose uptake increased by 40% and mitochondrial complex IV respiration was compromised by 20%. HIF1α-regulated genes and histone H3 lysine 9 (H3K9) acetylation, a known SIRT6 target, were increased in shNampt KD cells. Thus, we propose that the shift towards glycolytic metabolism observed, at least in part, is mediated by the SIRT6/HIF1α axis. Our findings suggest that NAMPT plays a key role for maintaining NAD+ levels in skeletal muscle and that NAMPT deficiency compromises oxidative phosphorylation capacity and alters energy homeostasis in this tissue.

OriginalsprogEngelsk
TidsskriftAmerican Journal of Physiology: Endocrinology and Metabolism
Vol/bind314
Udgave nummer4
Sider (fra-til)E377-E395
Antal sider19
ISSN0193-1849
DOI
StatusUdgivet - 2018

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