Fig. 7: Citrin activity regulates pyruvate’s fate.

a Basal cytosolic pyruvate levels measured with Pyronic in control vs. knockdown of citrin in the presence and absence of extracellular Ca²⁺ (One-Way ANOVA with Tukey’s multiple comparison test, n = 9 for control 2 Ca²⁺ and 0 Ca²⁺, n = 10 for citrin KD 2 Ca²⁺ and 0 Ca²⁺; b Cytosolic pyruvate accumulation in response to LDH and MCT inhibition with GSK 2837808 A and AR-C155858, respectively (One-Way ANOVA with Tukey’s multiple comparison test, *p < 0.05, n = 9 for control 2 Ca²⁺ and 0 Ca²⁺, n = 10 for citrin KD 2 Ca²⁺ and 0 Ca²⁺). c Representative traces of mitochondrial pyruvate measurements with mito-PyronicSF in the presence of extracellular Ca²⁺ under control, citrin KD and MCU KD conditions. d Representative traces of mitochondrial pyruvate measurements with mito-PyronicSF in the absence of extracellular Ca²⁺ under control, citrin KD and MCU KD conditions. e Statistical analysis of mitochondrial pyruvate measurements as shown in c and d (One-Way ANOVA with Tukey’s multiple comparison test, n = 11 for control 2 Ca²⁺, n = 10 for control 0 Ca²⁺, n = 12 for MCU KD 2 Ca²⁺, n = 8 for MCU KD 0 Ca²⁺, n = 14 for citrin KD 2 Ca²⁺, n = 7 for citrin KD 0 Ca²⁺, *p < 0.05, n.s. p > 0.05; unpaired t-test, ^#p < 0.034, ^##p = 0.006, n.s., p = 0.463). f Comparison of mitochondrial ATP dynamics after 2 µM oligomycin addition in the presence and absence of extracellular Ca²⁺ ±1 mM pyruvate supplementation (One-Way ANOVA with Tukey’s multiple comparison test, **p < 0.01, ***p < 0.001, n = 14 for 2 Ca²⁺ no pyruvate), 20 for 0 Ca²⁺ no pyruvate, 14 for 2 Ca²⁺ pyruvate, 18 for 0 Ca²⁺ pyruvate).