2.4. Mitochondrial membrane potential, mitochondrial mass and
ROS detection
For FACS analysis, 1×105 cells were stained in PBS with the
indicated fluorescent dye for 25 min, washed, and resuspended in
200 μl PBS with 1% FCS. Individual cellular fluorescence signals were
then analyzed using a FACSCalibur (BD Biosciences). Mitochondrial
membrane mass and mitochondrial potential were measured by
staining with MitoTracker Green FM (60 nM; Invitrogen) and
MitoTracker Red (80 nM; Invitrogen), respectively, for 25 min.
Dihydrofluorescein diacetate (10 μg/ml) was used to stain for total
cellular hydrogen peroxide, dihydroethidium (80 μM) for cellular
superoxide, and MitoSox Red (5 μM; Invitrogen) for mitochondrial
superoxide. Antimycin A treatment was performed by treating cells
with vehicle (ethanol) or 20 μMantimycin A (250 μMstock in ethanol)
for 20 min followed by staining with MitoSox Red. Unstained cells
were analyzed as controls and used to gate on live cells for final
analysis using FlowJo software (TreeStar, Ashland, OR). Bar graphs
show combined median fluorescence values of three independent
cultures, with at least 3000 cells analyzed for each. Histograms show
the fluorescence-intensity distribution of cells as a percentage of total
gated cells (% max).