Extended Data Fig. 3: The mitochondrial mass, mitochondrial morphology and oxygen consumption rate of SRR-KO cells were rescued by pyruvate or acetate supplementation.

a. Transmission electron microscopy images showing the morphology of mitochondria in WiDr cells stably expressing SRR-GFP or GFP. Blue and orange dotted lines indicate mitochondria. Scale bars represent 2 and 0.5 µm (magnified images). Images are representative of n = 2 biologically independent experiments. b,c. Quantification of mitochondrial elongation (b) and number of cristae folds per micrometer of mitochondria (c) in WiDr cells stably expressing SRR-GFP or GFP using ImageJ. Mitochondrial elongation was derived from the reciprocal of circularity. Data are means ± SD of n = 59 (GFP) and 94 (SRR-GFP) mitochondria. d-f. Immunofluorescence assay (d) and Flow cytometry analysis (e) using MitoTracker Deep Red and oxygen consumption rate (f) of EV and SRR-KO HCT116 cells after incubation with 1 mM pyruvate, 5 mM acetate or vehicle (DDW) for 72 hours. Images are representative of n = 3 biologically independent experiments (d), and data are means ± SD of n = 3 biologically independent samples and are representative of two independent experiments (e and f). g. Transmission electron microscopy images showing the morphology of mitochondria in EV and SRR-KO DLD-1 cells after incubation with 1 mM pyruvate, 5 mM acetate or vehicle (DDW) for 72 hours. Blue and orange dotted lines indicate mitochondria. Scale bars represent 2 and 0.5 µm (magnified images). Images are representative of n = 2 biologically independent experiments. h,i. Quantification of mitochondrial elongation (h) and number of cristae folds per micrometer of mitochondria (i) in EV and SRR-KO DLD-1 cells after incubation with 1 mM pyruvate, 5 mM acetate or vehicle (DDW) for 72 hours using ImageJ. Mitochondrial elongation was derived from the reciprocal of circularity. Data are means ± SD of n = 104 (EV vehicle), 92 (sgSRR_2 vehicle), 113 (sgSRR_2 pyruvate) and 95 (sgSRR_2 acetate) mitochondria. j. Flow cytometry analysis using MitoTracker Deep Red of DLD-1 EV and SRR-KO cells transfected with control empty vector (pVec), Wild-type (WT)-SRR and Q155D-SRR. Data are means ± SD of n = 3 biologically independent samples and are representative of two independent experiments. P-values were determined by two-tailed Student’s t-test.