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. 2021 Nov 9;37(6):109989. doi: 10.1016/j.celrep.2021.109989

Figure 1.

Figure 1

Mitochondrial energy metabolism affects L. monocytogenes infection

(A) Overview of the approaches used to generate cellular models with increased or decreased mitochondrial energy metabolism. HCT116 cells grown in galactose (Gal)-containing medium are energetically dependent on mitochondrial respiration (green mitochondria), whereas cells grown in glucose (Glc)-containing medium are mainly glycolytic and rely less on mitochondrial respiration (light gray mitochondria). Cells depleted for the mitochondrial protein SURF1 (SURF1−/− cells) show decreased mitochondrial respiration (red mitochondria), which can be rescued by reintroducing the SURF1 gene (SURF1−/− + SURF1 cells, dark gray mitochondria). The wedge indicates the level of dependency on mitochondrial respiration for energy production for each cell model.

(B and C) Oxygen consumption rate (OCR; in picomoles per minute) of HCT116 Glc and Gal cells (B) and of HCT116 WT, SURF1−/−, and SURF1−/− + SURF1 cells (C) monitored in a Seahorse XFe96 analyzer. Three independent experiments were performed and data from one representative experiment with six biological replicates per condition are shown as mean ± standard deviation (SD) for each time point. The rates of basal respiration, respiration coupled to ATP production, and maximal respiration were statistically evaluated by two-tailed t tests (B) and one-way ANOVA with Dunnett’s post hoc test (C) (∗∗∗p < 0.001).

(D and E) Intracellular bacterial load in HCT116 Glc and Gal cells (D) and in HCT116 WT, SURF1−/−, and SURF1−/− + SURF1 infected with WT L. monocytogenes EGDe (MOI, 20). The left panel shows values for Gal cells relative to Glc cells and values for SURF1−/− and SURF1−/− + SURF1 cells relative to WT cells, and the right panel shows the absolute quantification (CFU/mL), for each time point. Three independent experiments were performed, and for both panels, one representative experiment with three biological replicates is shown as mean ± SD. Statistical significances were calculated by multiple t tests (D) and one-way ANOVA with multiple comparisons (E); both were further evaluated by the false discovery rate approach of Benjamini, Krieger ,and Yekutieli, with Q = 1% (ns, not significant; ∗∗p < 0.01; ∗∗∗p < 0.001).