Fig. 4. Lactate inactivates PDHA1 and CPT2 dependent on AARS2.

a Lactate treatments inactivate cellular PDHA1 and CPT2. C2C12 cells were treated with 10 mM lactate. The relative (to those from untreated C2C12 cells) specific activities of PDHA1 and CPT2 were determined (n = 3). b Me-Lac treatments decrease cellular OCRs. OCRs of C2C12 cells that were untreated or treated with 2 mM or 10 mM Me-Lac for 4 h (n = 3) were determined. c, d Me-Lac treatments inactivate cellular PDHA1 and CPT2. Relative specific activities (to those of untreated C2C12 cells) of PDHA1 (c) and CPT2 (d) in C2C12 cells that were untreated or treated with 2 mM or 10 mM Me-Lac (n = 3) were determined. e–h Lactate treatments decrease Ac-CoA influx from glycolysis and FAO. Relative ¹³C-Ac-CoA levels in ¹³C-glucose (e, f) and ¹³C-palmitate (g, h) (to untreated C2C12 cells) and ¹³C-Ac-CoA (M + 2 only)-treated C2C12 cells, Aars2 KO C2C12 cells (e, g) and HL-1 cells, Aars2 KO HL-1 cells (f, h) were detected before and after being treated with 10 mM Me-Lac (n = 3). The chasing time for 10 mM ¹³C-glucose and 100 μM ¹³C-palmitate was 1 h and 12 h, respectively. All data are reported as mean ± SEM of three independent experiments. Statistical significance was assessed by unpaired two-tailed Student’s t-test and two-way ANOVA: *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001; ns no significance.