Bischof Helmut, Burgstaller Sandra, Springer Anna, Matt Lucas, Rauter Thomas, Bachkönig Olaf A, Schmidt Tony, Groschner Klaus, Schindl Rainer, Madl Tobias, Plesnila Nikolaus, Lukowski Robert, Graier Wolfgang F, Malli Roland
Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria.
Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tuebingen, Auf der Morgenstelle 8, 72076 Tuebingen, Germany.
iScience. 2021 Mar 22;24(4):102346. doi: 10.1016/j.isci.2021.102346. eCollection 2021 Apr 23.
High expression levels of mitochondria-associated hexokinase-II (HKII) represent a hallmark of metabolically highly active cells such as fast proliferating cancer cells. Typically, the enzyme provides a crucial metabolic switch towards aerobic glycolysis. By imaging metabolic activities on the single-cell level with genetically encoded fluorescent biosensors, we here demonstrate that HKII activity requires intracellular K. The K dependency of glycolysis in cells expressing HKII was confirmed in cell populations using extracellular flux analysis and nuclear magnetic resonance-based metabolomics. Reductions of intracellular K by gramicidin acutely disrupted HKII-dependent glycolysis and triggered energy stress pathways, while K re-addition promptly restored glycolysis-dependent adenosine-5'-triphosphate generation. Moreover, expression and activation of K1.3, a voltage-gated K channel, lowered cellular K content and the glycolytic activity of HEK293 cells. Our findings unveil K as an essential cofactor of HKII and provide a mechanistic link between activities of distinct K channels and cell metabolism.
线粒体相关的己糖激酶-II（HKII）的高表达水平是代谢高度活跃细胞（如快速增殖的癌细胞）的一个标志。通常，该酶为向有氧糖酵解的关键代谢转换提供支持。通过使用基因编码的荧光生物传感器在单细胞水平上对代谢活动进行成像，我们在此证明HKII活性需要细胞内的钾离子（K）。利用细胞外通量分析和基于核磁共振的代谢组学技术，在细胞群体中证实了表达HKII的细胞中糖酵解对钾离子的依赖性。短杆菌肽使细胞内钾离子减少，从而急性破坏了HKII依赖的糖酵解并触发了能量应激途径，而重新添加钾离子则迅速恢复了糖酵解依赖的三磷酸腺苷生成。此外，电压门控钾通道K1.3的表达和激活降低了细胞内钾含量以及HEK293细胞的糖酵解活性。我们的研究结果揭示了钾离子是HKII的必需辅助因子，并在不同钾通道的活性与细胞代谢之间建立了机制联系。
