Fig. 2: Reduced KGDH enzyme complex in CHCHD2-deficient cells.
A Schematic of U-13C6 glucose flux into the TCA cycle. After the first turn of TCA cycle, pyruvate incorporates three carbons (M + 3), while citrate, α-KG, succinate, fumarate and malate each incorporate two carbons (M + 2) derived from the initial U-13C6-labeled glucose. B–H The levels of unlabeled (M + 0) and 13C labeled (M + N) pyruvate, citrate/iso citrate, α-KG, succinate, fumarate, malate and glutamate in CHCHD2-deficient and control HEK293T cells after 6 h of labeling with U-13C6 glucose. The levels of metabolites were normalized by the levels of 13C6 glucose (Glc) for each sample. N = 3 biological replicates for CHCHD2 knockout and control cells. All data shown are mean ± SEM. ns, not significant. Two-sided t test. I Schematic of the conversion of α-KG to Succinyl-CoA catalyzed by KGDH enzyme complex. TPP: thiamine pyrophosphate, LA: lipoic acid, DHLA: dihydrolipoic acid, E1: oxoglutarate dehydrogenase (OGDH), E2: dihydrolipoyl succinyltransferase (DLST), E3: dihydrolipoyl dehydrogenase (DLD). Created in BioRender. Gao, G. (2025) https://BioRender.com/j39s594. J–M Protein levels of OGDH, DLST and DLD in control and two independent clones of CHCHD2 knockout HEK293T cells. N = 12, 11, and 6 biological replicates for control, D2 KO #1 and D2 KO #2, respectively. All data shown are mean ± SEM. One-way ANOVA with Dunnett’s test. N, O KGDH enzyme activities of control and CHCHD2-deficient cells. N = 6 biological replicates. Data shown are mean ± SEM. One-way ANOVA with Dunnett’s test. P–S Immunoblots and quantifications of OGDH, DLST and DLD protein levels of control and CHCHD10-deficient (D10 KO) HEK293T cells. N = 4 biological replicates. Data shown are mean ± SEM. ns, not significant. Two-sided t test. T, U KGDH enzyme activities of control and CHCHD10-deficient cells. N = 5 biological replicates. Data shown are mean ± SEM. ns, not significant. Two-sided t test. Source data are provided as a Source Data file.
