Nicotinamide adenine dinucleotide is transported into mammalian mitochondria
- University of Pennsylvania, United States
- Princeton University, United States
- Queen's University Belfast, United Kingdom
- Northeast Agricultural University, China
Abstract
Mitochondrial NAD levels influence fuel selection, circadian rhythms, and cell survival under stress. It has alternately been argued that NAD in mammalian mitochondria arises from import of cytosolic nicotinamide (NAM), nicotinamide mononucleotide (NMN), or NAD itself. We provide evidence that murine and human mitochondria take up intact NAD. Isolated mitochondria preparations cannot make NAD from NAM, and while NAD is synthesized from NMN, it does not localize to the mitochondrial matrix or effectively support oxidative phosphorylation. Treating cells with nicotinamide riboside that is isotopically labeled on the nicotinamide and ribose moieties results in the appearance of doubly labeled NAD within mitochondria. Analogous experiments with doubly labeled nicotinic acid riboside (labeling cytosolic NAD without labeling NMN) demonstrate that NAD(H) is the imported species. Our results challenge the long-held view that the mitochondrial inner membrane is impermeable to pyridine nucleotides and suggest the existence of an unrecognized mammalian NAD (or NADH) transporter.
Data availability
Source data for the figures has been submitted to Dryad doi:10.5061/dryad.qt58k
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Data from: Nicotinamide adenine dinucleotide is transported into mammalian mitochondriaAvailable at Dryad Digital Repository under a CC0 Public Domain Dedication.
Article and author information
Author details
Eiko Nakamaru-Ogiso
Funding
National Institute of Diabetes and Digestive and Kidney Diseases (R01DK098656)
- Joseph A Baur
National Institute on Aging (R01AG043483)
- Joseph A Baur
National Institute of General Medical Sciences (K12DGM081259)
- Antonio Davila
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: This study was performed in strict accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health. No live animal work was performed, and animals that were sacrificed for mitochondrial isolation were euthanized according to protocols approved by the institutional animal care and use committee (IACUC) of the University of Pennsylvania (protocol # 804892).
Copyright
© 2018, Davila et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Nicotinamide adenine dinucleotide is transported into mammalian mitochondria
eLife 7:e33246.
https://doi.org/10.7554/eLife.33246
