Figure 4.

MAP4K4 Inhibition Rescues Mitochondrial Function, Calcium Cycling, and Contractile Function in Human Ventricular Myocytes

(A–C) Calcium oscillations in vCor.4U cells. Protection was confirmed in three independent experiments; one representative set of dose-response curves is shown (4 replicate wells for each condition).

(A) Spontaneous calcium transients at 24 h were suppressed by menadione even at sub-lethal concentrations (CellTiter-Glo assay).

(B) Rescue by DMX-5804.

(C) Representative calcium transients. (Left) DMX-5804 had no effect on baseline calcium cycling. (Right) Preservation of calcium cycling by DMX-5804 in menadione-treated cells is shown.

(D) Mitochondrial function was assessed in vCor.4U cells using menadione as the oxidative stress (15 μM; 2 h), followed by the sequential inhibitors shown. Mitochondrial respiration (left) and glycolysis (center) were suppressed by menadione and rescued by 10 μM DMX-5804. For pairwise comparisons, ^∗p < 0.001 versus menadione; ^∗∗p ≤ 0.01 versus menadione. p values (right) denote treatment effects calculated as area under the curve (AUC).

(E) vCor.4U cells were cultured as 3D engineered heart tissue and subjected to menadione for 24 h ± DMX-5804. (Left) Suppression of cell death at 24 h is shown. ^∗p < 0.001 versus menadione; ^∗∗p = 0.02 versus menadione. (Center) Preservation of spontaneous beating at 1 and 24 h is shown. ^∗p < 0.001 versus menadione; ^∗∗p ≤ 0.03 versus menadione. (Right) Preservation of force generation is shown. ^∗p < 0.001 versus menadione; ^∗∗p = 0.008 versus menadione.

Results are shown as the mean ± SE.