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Cell Metab. 2018 May 1;27(5):1067-1080.e5. doi: 10.1016/j.cmet.2018.03.018.

Quantitative Analysis of NAD Synthesis-Breakdown Fluxes.

Author information

1
Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08540, USA; Department of Chemistry, Princeton University, Princeton, NJ 08540, USA; Diabetes Research Center, University of Pennsylvania, Philadelphia, PA 19104, USA.
2
Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08540, USA; Department of Medicine, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ 08904, USA.
3
Department of Physiology and Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
4
Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08540, USA.
5
Department of System Biology, Harvard Medical School, Boston, MA 02115, USA; Shire, Lexington, MA 02421, USA.
6
School of Pharmacy, Queen's University Belfast, Belfast, Northern Ireland BT9 7BL, UK.
7
Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08903, USA.
8
School of Pharmacy, Queen's University Belfast, Belfast, Northern Ireland BT9 7BL, UK; Mitchell Cancer Institute, University of South Alabama, Mobile, AL 36604, USA.
9
Department of System Biology, Harvard Medical School, Boston, MA 02115, USA. Electronic address: timothy_mitchison@hms.harvard.edu.
10
Department of Physiology and Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. Electronic address: baur@mail.med.upenn.edu.
11
Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08540, USA; Department of Chemistry, Princeton University, Princeton, NJ 08540, USA; Diabetes Research Center, University of Pennsylvania, Philadelphia, PA 19104, USA. Electronic address: joshr@princeton.edu.

Abstract

The redox cofactor nicotinamide adenine dinucleotide (NAD) plays a central role in metabolism and is a substrate for signaling enzymes including poly-ADP-ribose-polymerases (PARPs) and sirtuins. NAD concentration falls during aging, which has triggered intense interest in strategies to boost NAD levels. A limitation in understanding NAD metabolism has been reliance on concentration measurements. Here, we present isotope-tracer methods for NAD flux quantitation. In cell lines, NAD was made from nicotinamide and consumed largely by PARPs and sirtuins. In vivo, NAD was made from tryptophan selectively in the liver, which then excreted nicotinamide. NAD fluxes varied widely across tissues, with high flux in the small intestine and spleen and low flux in the skeletal muscle. Intravenous administration of nicotinamide riboside or mononucleotide delivered intact molecules to multiple tissues, but the same agents given orally were metabolized to nicotinamide in the liver. Thus, flux analysis can reveal tissue-specific NAD metabolism.

KEYWORDS:

NAD; NADH; flux quantification; isotope tracers; mass spectrometry; mononucleotide; niacin; nicotinamide; redox cofactor; riboside

PMID:
29685734
PMCID:
PMC5932087
[Available on 2019-05-01]
DOI:
10.1016/j.cmet.2018.03.018

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