Hepatocyte Hyperproliferation upon Liver-Specific Co-disruption of Thioredoxin-1, Thioredoxin Reductase-1, and Glutathione Reductase

Publication date: 27 June 2017
Source:Cell Reports, Volume 19, Issue 13
Author(s): Justin R. Prigge, Lucia Coppo, Sebastin S. Martin, Fernando Ogata, Colin G. Miller, Michael D. Bruschwein, David J. Orlicky, Colin T. Shearn, Jean A. Kundert, Julia Lytchier, Alix E. Herr, Åse Mattsson, Matthew P. Taylor, Tomas N. Gustafsson, Elias S.J. Arnér, Arne Holmgren, Edward E. Schmidt
Energetic nutrients are oxidized to sustain high intracellular NADPH/NADP⁺ ratios. NADPH-dependent reduction of thioredoxin-1 (Trx1) disulfide and glutathione disulfide by thioredoxin reductase-1 (TrxR1) and glutathione reductase (Gsr), respectively, fuels antioxidant systems and deoxyribonucleotide synthesis. Mouse livers lacking both TrxR1 and Gsr sustain these essential activities using an NADPH-independent methionine-consuming pathway; however, it remains unclear how this reducing power is distributed. Here, we show that liver-specific co-disruption of the genes encoding Trx1, TrxR1, and Gsr (triple-null) causes dramatic hepatocyte hyperproliferation. Thus, even in the absence of Trx1, methionine-fueled glutathione production supports hepatocyte S phase deoxyribonucleotide production. Also, Trx1 in the absence of TrxR1 provides a survival advantage to cells under hyperglycemic stress, suggesting that glutathione, likely via glutaredoxins, can reduce Trx1 disulfide in vivo. In triple-null livers like in many cancers, deoxyribonucleotide synthesis places a critical yet relatively low-volume demand on these reductase systems, thereby favoring high hepatocyte turnover over sustained hepatocyte integrity.

Graphical abstract

Teaser

All cells require cytosolic disulfide-reducing power fueled by intracellular NADPH or, in mammals, alternatively generated by catabolism of the essential amino acid methionine. Prigge et al. show that liver homeostasis under cytosolic disulfide reductase paucity involves noncanonical trafficking of reducing power and a hyperproliferation-based organ survival strategy.


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