FIGURE 2. BH3 mimetics disrupt mitochondrial function and structure in a GSH-sensitive manner.

A, mitochondrial membrane potential was measured in live CGNs using the dual emission fluorophore, JC-1. Control (CTRL) CGNs showed substantial red fluorescence indicative of aggregated JC-1, which localizes to healthy mitochondria (left). After the addition of 15 μm HA14 for 4 h, mitochondria were largely depolarized as indicated by the primarily green staining characteristic of monomeric JC-1 dye (middle). Co-incubation with 2 mm GSH monoethyl ester preserved the mitochondrial membrane potential even in the presence of the BH3 mimetic (right). Scale bar, 10 microns. B, mitochondrial structure was assessed in live CGNs using the fluorescent probe, Mitotracker green. CTRL or GSH-treated CGNs displayed healthy, largely tubular mitochondria (left column). In contrast, the mitochondria of HA14-treated or CMPD6-treated CGNs became round and fragmented (upper middle and upper right). Co-incubation with GSH protected mitochondria from the structural damage caused by these BH3 mimetics (lower middle and lower right). Scale bar, 5 microns. C and D, CGNs were treated with either 15 μm HA14 (C) or 50 μm CMPD6 (D) for 24 h in either the absence or presence of2 mm GSH. Degradation of the mitochondrial fusion GTPase, OPA1, was assessed by Western blotting. Actin is shown as a loading control.