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

• Published in: Scientific reports Vol. 7; no. 1; pp. 9723 - 16
• Main Authors: Capitanio, Daniele, Fania, Chiara, Torretta, Enrica, Viganò, Agnese, Moriggi, Manuela, Bravatà, Valentina, Caretti, Anna, Levett, Denny Z. H., Grocott, Michael P. W., Samaja, Michele, Cerretelli, Paolo, Gelfi, Cecilia
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 29.08.2017; Nature Publishing Group
• Subjects: 38; 38/77; 631/45/475/2290; 692/4017; 82; 82/1; 82/29; 82/58; Adaptation, Physiological; Animals; Autophagy; Basic Helix-Loop-Helix Transcription Factors - genetics; Basic Helix-Loop-Helix Transcription Factors - metabolism; Citric Acid Cycle; Energy demand; Energy Metabolism; Enzymatic activity; Gene Expression; Glutamine; Hexosamines - metabolism; High-altitude environments; Homeostasis; Human subjects; Humanities and Social Sciences; Humans; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit - genetics; Hypoxia-Inducible Factor 1, alpha Subunit - metabolism; Metabolic Networks and Pathways; Metabolism; Models, Biological; multidisciplinary; Muscle, Skeletal - metabolism; Musculoskeletal system; Oxygen - metabolism; Proteome; Proteomics; Proteomics - methods; Rodentia; Rodents; Science; Science (multidisciplinary); Signal Transduction; Skeletal muscle; Time Factors; Tricarboxylic acid cycle
• DOI: 10.1038/s41598-017-10097-4
• ISSN: 2045-2322

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 2 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 O 2 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-2α 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.