Potential role for pyruvate kinase M2 in the regulation of murine cardiac glycolytic flux during in vivo chronic hypoxia

Handzlik, Michal K.; Tooth, David J.; Constantin-Teodosiu, Dumitru; Greenhaff, Paul L.; Cole, Mark A.

Abstract

Carbohydrate metabolism in heart failure shares similarities to that following hypoxic exposure, and is thought to maintain energy homeostasis in the face of reduced O2 availability. As part of these in vivo adaptations during sustained hypoxia, the heart upregulates and maintains a high glycolytic flux, but the underlying mechanism it is still elusive. We followed the cardiac glycolytic responses to a chronic hypoxic (CH) intervention using [5-3H]-glucose labelling in combination with detailed and extensive enzymatic and metabolomic approaches to provide evidence of the underlying mechanism that allows heart survivability. Following three weeks of in vivo hypoxia (11% oxygen), murine hearts were isolated and perfused in a retrograde mode with function measured via an intraventricular balloon and glycolytic flux quantified using [5-3H]-glucose labelling. At the end of perfusion, hearts were flash-frozen and central carbon intermediates determined via liquid chromatography tandem mass spectrometry (LC-MS/MS). The maximal activity of glycolytic enzymes considered rate-limiting was assessed enzymatically, and protein abundance was determined using Western blotting. Relative to normoxic hearts, CH increased ex vivo cardiac glycolytic flux 1.7-fold with no effect on cardiac function. CH upregulated cardiac pyruvate kinase (PK) flux 3.1-fold and cardiac pyruvate kinase M2 (PKM2) protein content 1.4-fold compared to normoxic hearts. CH also augmented cardiac pentose phosphate pathway flux, reflected by higher ribose-5-phosphate content. These findings support an increase in the covalent (protein expression) and allosteric (flux) control of PKM2 as being central to the sustained upregulation of the glycolytic flux in the chronically hypoxic heart.

Citation

Handzlik, M. K., Tooth, D. J., Constantin-Teodosiu, D., Greenhaff, P. L., & Cole, M. A. (2021). Potential role for pyruvate kinase M2 in the regulation of murine cardiac glycolytic flux during in vivo chronic hypoxia. Bioscience Reports, 41(6), Article BSR20203170. https://doi.org/10.1042/bsr20203170

• Journal Article Type: Article
• Acceptance Date: Mar 22, 2021
• Online Publication Date: Jun 2, 2021
• Publication Date: May 1, 2021
• Deposit Date: Mar 31, 2021
• Publicly Available Date: May 1, 2021
• Journal: Bioscience Reports
• Print ISSN: 0144-8463
• Electronic ISSN: 1573-4935
• Publisher: Portland Press
• Peer Reviewed: Peer Reviewed
• Volume: 41
• Issue: 6
• Article Number: BSR20203170
• DOI: https://doi.org/10.1042/bsr20203170
• Keywords: Biophysics; Cell Biology; Biochemistry; Molecular Biology
• Public URL: https://nottingham-repository.worktribe.com/output/5425842
• Publisher URL: https://portlandpress.com/bioscirep/article/doi/10.1042/BSR20203170/228626/Potential-Role-For-Pyruvate-Kinase-M2-In-The