FIG. 4.
Prep1i/i MEFs have a lower mitochondrial-membrane potential (ΔΨm), which is further decreased upon genotoxic stress. (A) Untreated, 200 μM etoposide-treated or UV-C light (254 nm; 60 or 1,000 J/m2)-irradiated MEFs from Prep1+/+ (+/+) and Prep1i/i (i/i) embryos were stained with JC-1 (10 μM) for 30 min at 37°C and analyzed by confocal microscopy 12 h after each treatment. Some cells displayed a partial shift of JC-1 emission from red to yellow-green (white arrows). The results shown are representative of two independent experiments with at least 20 fields observed. (B) FACScan analysis of JC-1-stained (see above) Prep1+/+ and Prep1i/i MEFs (from a different litter than for panel A). The cells were analyzed before and 12 h after 200 μM etoposide or UV-C light (254 nm; 60 J/m2) treatment.