Chronic hypoxia enhances β-oxidation-dependent electron transport via electron transferring flavoproteins

  • Hypoxia poses a stress to cells and decreases mitochondrial respiration, in part by electron transport chain (ETC) complex reorganization. While metabolism under acute hypoxia is well characterized, alterations under chronic hypoxia largely remain unexplored. We followed oxygen consumption rates in THP-1 monocytes during acute (16 h) and chronic (72 h) hypoxia, compared to normoxia, to analyze the electron flows associated with glycolysis, glutamine, and fatty acid oxidation. Oxygen consumption under acute hypoxia predominantly demanded pyruvate, while under chronic hypoxia, fatty acid- and glutamine-oxidation dominated. Chronic hypoxia also elevated electron-transferring flavoproteins (ETF), and the knockdown of ETF–ubiquinone oxidoreductase lowered mitochondrial respiration under chronic hypoxia. Metabolomics revealed an increase in citrate under chronic hypoxia, which implied glutamine processing to α-ketoglutarate and citrate. Expression regulation of enzymes involved in this metabolic shunting corroborated this assumption. Moreover, the expression of acetyl-CoA carboxylase 1 increased, thus pointing to fatty acid synthesis under chronic hypoxia. Cells lacking complex I, which experienced a markedly impaired respiration under normoxia, also shifted their metabolism to fatty acid-dependent synthesis and usage. Taken together, we provide evidence that chronic hypoxia fuels the ETC via ETFs, increasing fatty acid production and consumption via the glutamine-citrate-fatty acid axis.

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Author:Dominik Christian FuhrmannORCiDGND, Catherine Olesch, Nina Susanne KurrleORCiDGND, Frank SchnütgenORCiDGND, Sven Zukunft, Ingrid FlemingORCiD, Bernhard BrüneORCiD
URN:urn:nbn:de:hebis:30:3-490664
DOI:https://doi.org/10.3390/cells8020172
ISSN:2073-4409
Pubmed Id:https://pubmed.ncbi.nlm.nih.gov/30781698
Parent Title (English):Cells
Publisher:MDPI
Place of publication:Basel
Document Type:Article
Language:English
Year of Completion:2019
Date of first Publication:2019/02/18
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2019/03/14
Tag:TMEM126B; complex I; electron transport chain; fatty acids; glutamine; mitochondria; monocytes
Volume:8
Issue:2, Art. 172
Page Number:18
First Page:1
Last Page:18
Note:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
HeBIS-PPN:448054892
Institutes:Medizin / Medizin
Wissenschaftliche Zentren und koordinierte Programme / Sonderforschungsbereiche / Forschungskollegs
Dewey Decimal Classification:6 Technik, Medizin, angewandte Wissenschaften / 61 Medizin und Gesundheit / 610 Medizin und Gesundheit
Sammlungen:Universitätspublikationen
Licence (German):License LogoCreative Commons - Namensnennung 4.0