Malic enzyme tracers reveal hypoxia-induced switch in adipocyte NADPH pathway usage.

TitleMalic enzyme tracers reveal hypoxia-induced switch in adipocyte NADPH pathway usage.
Publication TypeJournal Article
Year of Publication2016
AuthorsLiu, L, Shah, S, Fan, J, Park, JO, Wellen, KE, Rabinowitz, JD
JournalNat Chem Biol
Volume12
Issue5
Pagination345-52
Date Published2016 May
ISSN1552-4469
Keywords3T3-L1 Cells, Adipocytes, Adipogenesis, Animals, Antibodies, Carbon, Carbon Dioxide, Folic Acid, Gene Expression Regulation, Enzymologic, Gene Knockdown Techniques, Malate Dehydrogenase, Mice, NADP, Oxygen Consumption, Pentose Phosphate Pathway, RNA, Small Interfering, Succinates
Abstract

<p>The critical cellular hydride donor NADPH is produced through various means, including the oxidative pentose phosphate pathway (oxPPP), folate metabolism and malic enzyme. In growing cells, it is efficient to produce NADPH via the oxPPP and folate metabolism, which also make nucleotide precursors. In nonproliferating adipocytes, a metabolic cycle involving malic enzyme holds the potential to make both NADPH and two-carbon units for fat synthesis. Recently developed deuterium ((2)H) tracer methods have enabled direct measurement of NADPH production by the oxPPP and folate metabolism. Here we enable tracking of NADPH production by malic enzyme with [2,2,3,3-(2)H]dimethyl-succinate and [4-(2)H]glucose. Using these tracers, we show that most NADPH in differentiating 3T3-L1 mouse adipocytes is made by malic enzyme. The associated metabolic cycle is disrupted by hypoxia, which switches the main adipocyte NADPH source to the oxPPP. Thus, (2)H-labeled tracers enable dissection of NADPH production routes across cell types and environmental conditions. </p>

DOI10.1038/nchembio.2047
Alternate JournalNat. Chem. Biol.
PubMed ID26999781
PubMed Central IDPMC4891982
Grant ListR01CA163591 / CA / NCI NIH HHS / United States
T32 CA009140 / CA / NCI NIH HHS / United States
R01 CA163591 / CA / NCI NIH HHS / United States
/ / Howard Hughes Medical Institute / United States
P30DK019525 / DK / NIDDK NIH HHS / United States
R01 AI097382 / AI / NIAID NIH HHS / United States
P30 DK019525 / DK / NIDDK NIH HHS / United States
5T32CA009140-40 / CA / NCI NIH HHS / United States
R01AI097382 / AI / NIAID NIH HHS / United States