Extended Data Fig. 7: PNP inhibitor forodesine blocks 13C incorporation from [13C5]-ribose-inosine into central metabolites but has little effect on [13C6]-glucose catabolism.
From: Inosine is an alternative carbon source for CD8+-T-cell function under glucose restriction
The same experiment as in Fig. 4 was performed using active human T cells with or without Foro in the presence of [13C5]-Ino or [13C6]-Glc for 24 h. The polar extracts from both tracer experiments were analyzed by 1D HSQC NMR for 13C abundance (spectra as shown). Selected metabolites were quantified as 13C μmole/g protein using the N-methyl resonance of phosphocholine (NMe-PCholine) as an internal standard, which are shown as bar graphs for the [13C5]-Ino (a) and [13C6]-glucose tracer (b) experiments. Values are average ± SEM (n=3). Sample size (n) represents biologically independent samples. Dashed line denotes the expected peak position of the H1-glucose resonance of glycogen. The proton resonances used for quantification were: 13C3-Lac/Ala – the H3 resonances of lactate/Ala; 13C-Gluta – the H4-Glu resonance of GSH + GSSG with minor contribution of H2,5 resonance of citrate; 13C-Ino, 13C-Glu, 13C-Asp, 13C-AXP, and 13C-UXP – H1’, H4, H3, and H1’ resonances of inosine, glutamate, aspartate, and adenine/uracil nucleotides, respectively.