Figure 5.

COX7A2L limits the entrance of glutamine-derived carbon source products into the TCA cycle. (A) Schematic diagram of glutaminolysis. (B-C) Relative abundance of metabolites from glutaminolysis pathway in WT and KO (B) as well as KO+Vector and KO+COX7A2L (C) cells. Data were obtained from untargeted metabolomics (n = 6) and outliers were excluded from statistical analysis. (D) Relative glutamine consumption in WT and KO as well as KO+Vector and KO+COX7A2L cells cultured in 5 mM glucose medium (n = 5). (E) Schematic diagram of ¹³C₅-glutamine metabolite labeling pattern. Blue and orange dots indicate ¹³C from oxidative and reductive metabolism, respectively. (F) ¹³C₅-glutamine metabolic flux analysis (MFA) of TCA intermediates in KO+Vector and KO+COX7A2L cells. (G-J) ¹³C₅-glutamine MFA of fumarate (G), malate (H), aspartate (I), and cis-aconitate (J) in WT and KO as well as KO+Vector and KO+COX7A2L cells. ¹³C₅-glutamine metabolic flux analysis was performed in six independent replicates. Quantitative data are presented as mean ± SEM. m0, unlabeled metabolite; m+, labeled metabolite; N.S, not significant; *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001, ****P ≤ 0.0001.