Dataset Information

TCA cycle rewiring fosters metabolic adaptation to oxygen restriction in skeletal muscle from rodents and humans.

ABSTRACT: In mammals, hypoxic stress management is under the control of the Hypoxia Inducible Factors, whose activity depends on the stabilization of their labile ? subunit. In particular, the skeletal muscle appears to be able to react to changes in substrates and O₂ delivery by tuning its metabolism. The present study provides a comprehensive overview of skeletal muscle metabolic adaptation to hypoxia in mice and in human subjects exposed for 7/9 and 19 days to high altitude levels. The investigation was carried out combining proteomics, qRT-PCR mRNA transcripts analysis, and enzyme activities assessment in rodents, and protein detection by antigen antibody reactions in humans and rodents. Results indicate that the skeletal muscle react to a decreased O₂ delivery by rewiring the TCA cycle. The first TCA rewiring occurs in mice in 2-day hypoxia and is mediated by cytosolic malate whereas in 10-day hypoxia the rewiring is mediated by Idh1 and Fasn, supported by glutamine and HIF-2? increments. The combination of these specific anaplerotic steps can support energy demand despite HIFs degradation. These results were confirmed in human subjects, demonstrating that the TCA double rewiring represents an essential factor for the maintenance of muscle homeostasis during adaptation to hypoxia.

SUBMITTER: Capitanio D

PROVIDER: S-EPMC5575144 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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TCA cycle rewiring fosters metabolic adaptation to oxygen restriction in skeletal muscle from rodents and humans.

Capitanio Daniele D Fania Chiara C Torretta Enrica E Viganò Agnese A Moriggi Manuela M Bravatà Valentina V Caretti Anna A Levett Denny Z H DZH Grocott Michael P W MPW Samaja Michele M Cerretelli Paolo P Gelfi Cecilia C

Scientific reports 20170829 1

In mammals, hypoxic stress management is under the control of the Hypoxia Inducible Factors, whose activity depends on the stabilization of their labile α subunit. In particular, the skeletal muscle appears to be able to react to changes in substrates and O<sub>2</sub> delivery by tuning its metabolism. The present study provides a comprehensive overview of skeletal muscle metabolic adaptation to hypoxia in mice and in human subjects exposed for 7/9 and 19 days to high altitude levels. The inves ...[more]

PMID: 28852047

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Project description:The fundamental dynamics of the cell cycle, underlying cell growth and reproduction, were previously found to be robust under a wide range of environmental and internal perturbations. This property was commonly attributed to its network structure, which enables the coordinated interactions among hundreds of proteins. Despite significant advances in deciphering the components and autonomous interactions of this network, understanding the interfaces of the cell cycle with other major cellular processes is still lacking. To gain insight into these interfaces, we used the process of genome-rewiring in yeast by placing an essential metabolic gene HIS3 from the histidine biosynthesis pathway, under the exclusive regulation of different cell-cycle promoters. In a medium lacking histidine and under partial inhibition of the HIS3p, the rewired cells encountered an unforeseen multitasking challenge; the cell-cycle regulatory genes were required to regulate the essential histidine-pathway gene in concert with the other metabolic demands, while simultaneously driving the cell cycle through its proper temporal phases. We show here that chemostat cell populations with rewired cell-cycle promoters adapted within a short time to accommodate the inhibition of HIS3p and stabilized a new phenotypic state. Furthermore, a significant fraction of the population was able to adapt and grow into mature colonies on plates under such inhibiting conditions. The adapted state was shown to be stably inherited across generations. These adaptation dynamics were accompanied by a non-specific and irreproducible genome-wide transcriptional response. Adaptation of the cell-cycle attests to its multitasking capabilities and flexible interface with cellular metabolic processes and requirements. Similar adaptation features were found in our previous work when rewiring HIS3 to the GAL system and switching cells from galactose to glucose. Thus, at the basis of cellular plasticity is the emergence of a yet-unknown general, non-specific mechanism allowing fast inherited adaptation to unforeseen challenges.

Project description:Skeletal muscle is the largest tissue in the body and mainly relies on mitochondrial oxidative metabolism for sustainable ATP production. Reduced oxygen availability, also known as hypoxia, can be caused by high altitude or pathology and impacts mitochondria. Whereas long-term hypoxia results in increased reliance on glycolysis, reduced fatty acid oxidation and a decreased skeletal muscle mass, the in vivo mechanisms of adaptation of skeletal muscle to acute hypoxia remain elusive. Therefore, we aimed to provide an integrated description of the response of the M. gastrocnemius to acute hypoxia. Fasted male C57BL/6JOlaHsd mice were exposed to 12% oxygen representing normobaric hypoxia versus 21% oxygen (normoxia) for six hours (n=12 mice per group). Whole-body energy metabolism and the transcriptome response of the M. gastrocnemius mice was analyzed and confirmed by acylcarnitine determination and RT-qPCR. On whole-body level, six hours of hypoxia reduced energy expenditure, increased blood glucose and tended to further decrease the respiratory exchange ratio (RER). Whole genome transcriptome analysis revealed upregulation of the FOXO signalling pathway including an increased expression of Trib3, which was positively correlated with blood glucose. Apart from upregulation of Cpt1a, which negatively correlated with the RER, and SLC25a25 (Cact), fatty acid β-oxidation was not regulated. Together with significantly increased muscle C14 and C16-acylcarnitines this supports no increased fatty acid catabolism in muscle. In addition, the hypoxia-induced FOXO activation could also be connected to altered gene profiles related to fiber type switching, extracellular matrix remodelling, muscle differentiation and the denervation of neuromuscular junctions (NMJ). Conclusively, our results suggest that an acute, six hours exposure of mice to hypoxia impacts M. gastrocnemius via FOXO1, initiating alterations in skeletal muscle that may ultimately contribute to tissue remodelling. This supports an early role of hypoxia in tissue alterations in hypoxia-associated conditions such as aging and obesity. The observed impact of hypoxia on denervated NMJ is novel and warrants further investigation.

Dataset Information

TCA cycle rewiring fosters metabolic adaptation to oxygen restriction in skeletal muscle from rodents and humans.

Publications

TCA cycle rewiring fosters metabolic adaptation to oxygen restriction in skeletal muscle from rodents and humans.

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