Abstract
Modulation of energy metabolism to a highly glycolytic phenotype, i.e. Warburg effect, is a common phenotype of cancer and activated immune cells allowing increased biomass-production for proliferation and cell division. Endoplasmic reticulum (ER)-localized ADP-dependent glucokinase (ADPGK) has been shown to play a critical role in T cell receptor activation-induced remodeling of energy metabolism, however the underlying mechanisms remain unclear. Therefore, we established and characterized in vitro and in vivo models for ADPGK-deficiency using Jurkat T cells and zebrafish. Upon activation, ADPGK knockout Jurkat T cells displayed increased cell death and ER stress. The increase in cell death resulted from a metabolic catastrophe and knockout cells displayed severely disturbed energy metabolism hindering induction of Warburg phenotype. ADPGK knockdown in zebrafish embryos led to short, dorsalized body axis induced by elevated apoptosis. ADPGK hypomorphic zebrafish further displayed dysfunctional glucose metabolism. In both model systems loss of ADPGK function led to defective N- and O-glycosylation. Overall, our data illustrate that ADPGK is part of a glucose sensing system in the ER modulating metabolism via regulation of N- and O-glycosylation.
Highlights
Www.nature.com/scientificreports about 0.09 and lacks end-product inhibition
Considering its localization at the endoplasmic reticulum (ER), we hypothesized that ADP-dependent glucokinase (ADPGK) site- provides glucose-6-phosphate for O-GlcNAc modifications or complex N / O-glycosylation, both being essential for T cell activation[7,8]
Using density gradient enriched ER fractions prepared via ultracentrifugation, we examined co-localization of ADPGK with different ER marker proteins
Summary
Www.nature.com/scientificreports about 0.09 and lacks end-product inhibition. Other remarkable features are its temperature optimum at about 42° and an acidic pH-optimum of about 65. We have shown that activation of Jurkat and primary human T cells leads to downregulation of mitochondrial respiration in concert with upregulation and deviation of glycolytic flux towards the glycerol-3-phosphat e-dehydrogenase-shuttle, resulting in the release of a mitochondrial ROS (reactive oxygen species) signal and steering NFκB-dependent gene expression[5]. This metabolic shift coincided with increased ADPGK activity and expression of NFκB target genes like IL(interleukin)-2 or IL-8 were strongly dependent on ADPGK activity[5]. We further tested the in vivo relevance of our findings by exploring the phenotype of ADPGK knockdown in zebrafish
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